Foreword - CCS HAU, Hisar

Vice-Chancellor 

CCS Haryana Agricultural University 

HISAR- 125 004 (Haryana) India 

FOREWORD 

Every year, a large proportion of crop yields are lost due to the attack of insectpests, 

diseases, weeds and other pests like rodents, etc. Such losses are particularly high 

in the developing countries. To determine what factors damaged the plants require investigative 

approach combined with careful observation and ability to put all the pieces together to 

reconstruct the event(s) that caused the damage. Accurate diagnosis must be made before 

undertaking corrective action. 

In diagnosing plant damage, a series of deductive steps can be followed to gather 

information and clues from the complex and general situation down to specific, individual 

plant or plant part. Thus, through the systematic diagnostic process of deduction and 

elimination, the most probable cause of the plant damage can be determined. Pest 

management decisions taken on the basis of incorrect identification of the causal agent of 

the damage could result in pest control failures and economic loss. 

Pest infestations often have adverse effect on yield. Therefore, it becomes essential 

to accurately estimate the potential role of each agent in reducing yields so that based on 

their incidence the potential losses could be predicted. The understanding of the mechanisms 

which are involved in quantitative and qualitative crop losses could help in formulating 

appropriate strategies to minimize them. It would help in identifying the economic status of 

different pests. With the introduction of new technologies, pest situations are changing. 

This is particularly visible in the case of GM crops. Some new pests are appearing and 

those which were earlier classified as minor pests are becoming important. Based on 

symptoms produced in the plants in response to insect feeding, we must be able to correctly 

identify the pests involved and assess the damage inflicted by them so that necessary 

measures for their management could be initiated in time. 

It gives me immense pleasure that the Centre of Advanced Faculty Training (CAFT) 

in the Department of Entomology has selected an appropriate topic “Advances in diagnosis 

of arthropod pests’ damage and assessment of losses” for the advanced training course. I 

hope this course would go a long way in creating deeper understanding among the participants 

regarding the investigative approaches required for appropriate diagnosis of plant damage 

and assessment of crop losses caused by insect-pests. 

I have all appreciation for Dr. R.K. Saini, Professor and Head-cum-Director CAFT, Dr. 

S.S. Sharma and Dr. K.K. Mrig, Course Coordinators, for planning and organizing this training 

course and bringing out this compendium. I wish the programme all success. 

(K. S. Khokhar)

Dean 

College of Agriculture 



MESSAGE 

I have come to know that the Department of Entomology, CCS Haryana Agricultural 

University, Hisar, under the auspices of Centre of Advanced Faculty Training (CAFT) is 

organizing an Advanced Training Course on “Advances in diagnosis of arthropod pests’ damage 

and assessment of losses” from September 6-26, 2011. Accurate diagnosis of pest damage 

symptoms produced on the plants and reliable estimation of crop losses in relation to pest 

attack are important scientific activities in pest management. Basic knowledge related to 

types of damage symptoms produced in plants by different pests, symptoms produced in 

plants due to non-living factors like soil conditions, temperature, hailstorms etc., and 

methodology of precise estimation of crop loss is essential to address the problem properly. 

The mechanisms responsible for quantitative and qualitative crop losses need to be understood 

critically so as to identify the economic status of the factor responsible. 

It is heartening to note that a compendium of lectures delivered during the training 

course is being published in the form of a book, which, I hope, would prove quite useful to 

the faculty, extension workers and students. I have all appreciation for Dr. R.K. Saini, Professor 

and Head-cum-Director CAFT, Dr. S. S. Sharma and Dr. K. K. Mrig, Course Coordinators, for 

planning and organizing this training course and bringing out this publication. 

I wish all success to the organizers. 

(Sucheta Khokhar)

Prof. & Head 

Department of Entomology 



PREFACE 

A variety of symptoms are produced in plants in response to insect feeding. The situation 

becomes complex when similar symptoms are produced on the same plant by completely different 

factors. Therefore, accurate diagnosis of pest damage symptoms produced on the plants and 

reliable estimation of crop losses in relation to pest attack are important scientific activities in 

pest management that are aimed at increased understanding of the factors responsible for plant 

damage and improved quantification of the effects of pests on crop growth and development. To 

arrive at logical conclusions, one must understand the mechanics of insect-plant interactions 

and how they affect crop yields. Efficient pest management depends on an accurate diagnosis of 

the pest problem. The first requirement is to determine whether an insect observed on a crop 

plant is a pest or not. Knowledge of insect mouthparts and the feeding mechanisms can greatly 

help in arriving at right conclusions. 

The present training course on “Advances in diagnosis of arthropod pests’ damage and 

assessment of losses” was organized from September 6 to 26, 2011 with the objective of providing 

update of the progress made in this field. 

Important aspects covered during this course included some basic information related to 

insect-plant loss interactions, common methods of crop loss assessment, types of damage 

symptoms, cropwise diagnostic symptoms of pest damage and loss assessment, and damage 

symptoms produced by agents other than insects. It also included miscellaneous chapters related 

to other supportive fields such as agrimeteorology, computer applications remote sensing, etc. 

Most of the lectures were contributed by the specialists from CCS Haryana Agricultural University, 

Hisar. However, some of these were delivered by experts from Gujarat Agricultural University, 

Sardar Krushi Nagar; Indian Agricultural Research Institute, New Delhi; S.K. Rajasthan Agricultural 

University, Bikaner and Punjab Agricultural University, Ludhiana. Twenty three participants 

representing 11 SAUs attended this course. 

The financial assistance from Indian Council of Agricultural Research (ICAR), New Delhi 

and help and cooperation received from different resource persons, faculty and staff of Department 

of Entomology and other departments of the University who have been associated with this course 

are gratefully acknowledged. 

I am indeed indebted to worthy Vice-Chancellor, Prof. K. S. Khokhar, for the patronage, 

support and encouragement given by him to this training programme. 

I express deep sense of gratitude Prof. Sucheta Khokhar, Dean, College of Agriculture, 

for her enormous help, guidance and interest. I owe my sincere thanks to Dr. R. P. Narwal, 

Director of Research, for his cooperation and help. Support from members of various committees 

engaged with this programme and the tireless efforts made by the Course Coordinators, Dr. K. K. 

Mrig and Dr. S. S. Sharma is thankfully acknowledged. I hope this compendium will be of great 

help to students, researchers, teachers and extension workers in understanding the aspects of 

plant clinic and crop loss assessment. 

(R. K. Saini)

No. TITLE AND NAME 

CONTENTS 

1. PLANT HEALTH DIAGNOSTICS AND LOSS ASSESSMENT: AN OVERVIEW 1 

R. K. SAINI 

2. INSECT' NOMENCLATURE, IDENTIFICATION, CLASSIFICATION AND THEIR 6 

ROLE IN STRENGTHENING PEST DIAGNOSTICS 

SUCHETA KHOKHAR 

3. A SYSTEMATIC APPROACH TO DIAGNOSING PLANT DAMAGE 1 4 

RAM SINGH 

4. METHODS OF ESTIMATING CROP LOSSES DUE TO INSECT-PESTS 22 

PALA RAM 

5. SIGNIFICANCE OF INSECT PEST-LOSS RELATIONSHIPS 26 

R. K. SAINI 

6. PROCEDURE FOR COLLECTING PLANT AND INSECT SAMPLES FOR 32 

PROBLEM DIAGNOSIS 

K. K. MRIG AND S. S. SHARMA 

7. INSECT SAMPLING FOR DECISION MAKING IN CROP LOSS ASSESSMENT 38 

R. K. SAINI 

8. DIAGNOSTIC SYMPTOMS AND ASSESSMENT OF LOSSES DUE TO 47 

ARTHROPOD PESTS IN KHARIF VEGETABLES 

S. S. SHARMA 

9. DIAGNOSITIC SYMPTOMS AND ASSESSMENT OF LOSSES DUE TO 51 

INSECT-PESTS IN WINTER VEGETABLES 

P. C. SHARMA 


WHITEGRUBS IN VARIOUS CROPS 

SWAROOP SINGH 

11. DIAGNOSTIC SYMPTOMS AND DAMAGE DUE TO INSECT-PESTS IN SOME 60 

TROPICAL AND SUB-TROPICAL FRUIT CROPS 

G. S. YADAV AND S. S. SHARMA 


ARTHROPOD PESTS IN TROPICAL FRUIT CROPS INCLUDING SOME 

PLANTATION CROPS 

G. M. PATEL 

13. DIAGNOSTIC SYMPTOMS AND LOSS ASSESSMENT DUE TO 72 

INSECT-PESTS IN COTTON 

K. K. DAHIYA 

14. DIAGNOSTIC SYMPTOMS AND ASSESSMENT OF LOSSES DUE 75 

TO INSECT-PESTS IN PADDY 

LAKHI RAM 


INSECT-PESTS IN PULSES 

ROSHAN LAL 

16. DIAGNOSIS AND CROP LOSS ASSESSMENT FOR ECONOMICALLY 83 

IMPORTANT PLANT DISEASES 

S. K. GANDHI 


NEMATODE PESTS IN IMPORTANT CROPS 

R. K. WALIA

18. DIAGNOSTIC SYMPTOMS OF MACRO AND MICRONUTRIENTS' 95 

DEFICIENCY IN IMPORTANT CROPS 

J. P. SINGH AND DEV RAJ 

19. DIAGNOSTICS AND ASSESSMENT OF LOSSES DUE TO INSECT-PESTS 105 

IN STORED DRY FRUITS 

AJAY K. SOOD 


INSECT- PESTS IN TEMPERATE FRUIT CROPS 

P. K. MEHTA AND R. S. CHANDEL 

21. DIAGNOSTIC SYMPTOMS AND LOSS ASSESSMENT DUE TO MITE 114 

PESTS IN IMPORTANT CROPS 

RACHNA GULATI 

22. PREDICTING INSECT POPULATIONS USING MODELS 121 

RAM NIWAS AND M. L. KHICHAR 

23. DIAGNOSTIC SYMPTOMS AND LOSSES CAUSED BY MAJOR 129 

ENEMIES TO HONEY BEES 

S. K. SHARMA 


ARTHROPOD PESTS IN CROPS 

M. K. DHILLON 

25. DIAGNOSTIC SYMPTOMS AND LOSS ASSESSMENT DUE 141 

TO INSECT-PESTS IN FORAGE CROPS 

S. P. SINGH 


TO INSECT- PESTS IN POTATO 

R. S. CHANDEL AND MANDEEP PATHANIA 


INSECT-PESTS IN OILSEED CROPS 

S. P. SINGH 


INSECT-PESTS IN SPICES 

YOGESH KUMAR 

29. REMOTE SENSING AND ITS APPLICATION IN PEST DAMAGE DIAGNOSIS 158 

RAMESH S. HOODA 

30. USE OF ADVANCED COMPUTER TOOLS IN SCIENTIFIC PRESENTATIONS 165 

A. K. CHHABRA 

31. METHODOLOGY OF PESTICIDE RESIDUE ESTIMATION IN 171 

VARIOUS FIELD CROPS 

BEENA KUMARI 

32. DIAGNOSTICS AND LOSS ASSESSMENT DUE TO INSECT-PESTS 179 

IN SUGARCANE 

SAROJ JAIPAL 


INSECT-PESTS IN CEREAL CROPS 

OMBIR 


TO INSECT-PESTS IN STORED GRAINS 

S. S. SHARMA 

35. MOLECULAR MARKERS : CONCEPTS AND THEIR APPLICATIONS 196 

IN ENTOMOLOGY 

A. K. CHHABRA 


INSECT-PESTS IN RABI VEGETABLES 

S. S. SHARMA AND V. S. MALIK

PLANT HEALTH DIAGNOSTICS AND LOSS ASSESSMENT : 

AN OVERVIEW 

R. K. Saini 


CCS Haryana Agricultural University, Hisar 

Plant health is affected by a number of living and non-living factors. Living factors include 

insect-pests, mites, weeds, disease causing agents like fungi, bacteria, viruses, nematodes, 

and other living organisms, while the non-living factors include environmental variables like 

temperature, humidity, rainfall, hailstorms, winds, drought, sunshine and soil condition, etc. 

To determine what factor(s) adversely affected plant requires investigative approach combined 

with careful observation and ability to put all the pieces together to reconstruct the event(s) 

that affected the plant. Accurate diagnosis must be made before corrective action can be 

initiated. Similarities of symptoms produced on the same plant by completely different factors 

frequently make the use of symptoms alone inadequate. Insects may harm the plants in 

different ways such as damage caused due to feeding, oviposition or disease transmission. 

However, diagnosis becomes easier if the insect causing damage is also observed and 

identified. 

Accurate pest management depends on an accurate diagnosis of the problem. The first 

requirement is to determine whether an insect observed on a crop plant is a pest or not. The 

type of mouthparts of an insect species and the manner of feeding on the host plant are both 

important determinants of its pest status. Treatment without diagnosis, as in medicine, is a 

malpractice. Despite this, diagnosis is often not given adequate attention. There are three 

challenges to consider when embarking on plant diagnostics : 

1. Some plant problems are very obvious, while others are very obscure. 

2. Some plant problems will not be diagnosed with the first effort. In fact, some plant problems 

may never be diagnosed. 

3. Farmers usually want an immediate and clear cut answer which exert great pressure to 

provide quick-draw and clear-cut diagnosis. 

Typically, diagnostics is a process to come up with the best possible explanation of why 

a good plant has gone wrong. An incorrect diagnosis will lead to an incorrect treatment. A 

plant may be suffering from multiple problems, and the most obvious may not be most 

significant. For arriving at a logical conclusion, one has to observe the problem from different 

perspectives: 

A. Knowing the plants : A good diagnostician must be able to understand the difference 

between a normal and an abnormal plant, which could provide a great early perspective 

in the diagnosis process. All plants have their own set of diseases and insect problems. 

Knowing the plants and what family and genus do they belong, is a great starting point 

for diagnostics. 

B. Looking for abnormalities in the plants : Plant abnormalities are categorized in terms 

of signs and symptoms. Signs are the actual causal agents. Symptoms result from 

interaction between the plant and pests, pathogens, or environmental elements (e.g. 

high soil pH). However, some symptoms may be produced by multiple causes. Twisted 

leaves may be caused by sucking pests like leafhopper, thrips, or leafminer or exposure 

to plant growth regulator herbicides. Similarly, tiny leaf spots can be caused by a leaf 

spotting fungus or bacterium, or lace bugs and mites. Yellow leaves may be caused by 

sucking pests or by nutrient deficiencies in the soil or by a soil pH that makes the 

1

nutrients unavailable to the plants. Pattern of damage is characteristics of some particular 

insect species which can be very helpful in diagnosis. Some of the major symptoms 

produced in plants include chewed leaves or blossoms, e.g. defoliation, shot holes, 

margins notched, skeletonization; discoloured leaves or blossoms eg. Stippling, streaking, 

mining, yellowing; distorted leaves, branches, or trunks e.g. leaf cupping, leaf or twig 

galling, bark cracking; dieback of shoots, twigs and branches e.g. shoot die-back, branch 

dieback; products of insects e.g. honeydew and sooty mold, fecal spots, silk, protective 

coverings, fluffy white wax, soft or hard white, brown, gray or black covers, etc. Therefore, 

examine all plant parts closely and carefully. 

C. Knowledge about plant site conditions and environmental history : Conditions 

under which a plant is growing also affect plant growth and development. This may not 

be confused with the stunted growth caused by sap sucking insects. Poorly drained soil 

with poor internal aeration may result in death of plants. Acid loving plants often develop 

yellowing between the veins (interveinal chlorosis) if growing in alkaline soils (pH above 

7) due to iron deficiency. 

Plant stress may also produce a progression of symptoms. There are two types of plant 

stress: acute and chronic. Acute stress is caused by an immediate event, such as 

feeding, drought, leaf defoliation, etc. Symptoms are usually immediately visible and 

easy to diagnose. Chronic stress is caused by more subtle conditions such as site 

problem or agronomical problem. How harsh have been the winters or summers need to 

be known. 

D. Knowledge of available diagnostic tools : Useful tools for diagnosis can be high 

tech, ranging from elaborate microscope and enzyme linked immunosorbent assay tests 

for virus and fungi in diagnostic labs to simpler tools e.g. soil probe (to check soil pH), 

hand lens (10 X or 20X magnification), cutting tools (e.g. good sharp hand pruners and 

knife), digging tools (to check girdling roots e.g. spade), recording tools (e.g. a field 

note-book), a digital camera, a hand-held recorder, sampling equipment like specimen 

tubes, plastic bags, etc. 

E. Reporting of diagnosis and recommendations : Describe the symptoms observed 

clearly and in detail. Identify the problem(s) you think these symptoms signify. After 

making a diagnosis, it is important to put the suggested problem into proper perspective 

relative to overall plant health. While recommending treatment for the problem, remember 

that sometimes “doing nothing” is the best recommendation when the problem is of 

minor importance. Most healthy herbaceous and woody plants can tolerate 20 to 30 per 

cent leaf defoliation without suffering long-term damage or yield reduction. Secondly, 

sometimes nothing can be done to make the plant recover. In such cases, often the best 

recommendation is for timely removal and replacement of the plant. Knowledge of pest 

life cycle and thereby crucial timing of initiating a control measure is very important. The 

recommendations should be made within a range of proper expectations. Finally, the art 

and science of professional plant diagnostics are often overlooked by those with instant 

answers to every problem. 

NEW TECHNOLOGIES 

Use of computer based expert systems in pest diagnosis : Expert systems have 

developed from a branch of computer science known as artificial intelligence. Artificial 

intelligence is primarily concerned with knowledge representation, problem solving, learning, 

robotics, and the development of computers that can speak and understand human like 

languages. Thus, expert systems are computer programmes designed to mimic the thought 

and reasoning processes of human expert. 

2

Expert system can be developed for many kinds of applications involving diagnosis, prediction, 

consultation, information retrieval, control, planning, interpretation and instruction. 

In USA, computer based diagnostic systems for diseases, insect-pests and physiological 

disorders are available. In citrus and selected tropical fruit crops, the TFRUIT.Xpert and 

CIT.Xpert computer based diagnostic programmes can quickly assist commercial producers, 

extension agents and homeowners in the diagnosis of diseases, insect-pest problems and 

physiological disorders. The systems’ methodology reproduces the diagnostic reasoning 

process of the experts. The diagnostic programme operates under Microsoft-Windows. Users 

can also refer to summary documents and retrieve management information from the University 

of Florida’s Institute of Food and Agricultural Sciences extension publications through 

hypertext links. The programme are available separately on CD-ROM and each contains 

over 150 digital colour images of symptoms. 

Simulation models : Computer models can provide some theoretical explanations of 

the effect of injurious or competitive organisms on crops. In general, computer models depend 

on a few known variables that influence plant growth, development, and production. However, 

in reality plants respond to damage or changes in the environment in a very complex manner. 

Thus far, such complexity cannot be incorporated into the models to simulate an actual 

situation. However, good simulations or computer models can improve the theoretical 

understanding of the major effects of injuries or damages of pests on plants and their yield. 

Imaging Technologies : New technologies and improvements to existing technologies 

are constantly changing the way we view objects. With the proliferation of mobile computing 

hardware and personal communications devices, for example, the possible development of 

portable imaging systems is becoming more realistic. These changes are not just taking 

place in the computing arena. Small, portable microscopes are now available that support 

digital photomicrography and are still capable of providing the same levels of magnification 

as their bench-top counterparts. 

When photographs or image recordings from a tower, balloon, plane, or satellite are 

available, they can give a useful indication of the area and intensity of dead or wilting plants 

or leaves and differences in crop yield caused by pest attack. Remote sensing techniques 

such as radar can automatically monitor the height, horizontal speed, direction, orientation, 

body mass and the shape of arthropods intercepting the radar beam. It can provide information 

of aerial migration of pests and natural enemies. It can be particularly useful for monitoring 

locust swarms. Radar entomology was first used in 1968 and since then comprehensive and 

intensive studies have been conducted in the UK, USA, Australia and China and it was 

predicted that fully automatic, season long and real time monitoring will be feasible with the 

vertical-looking radar (Zhai, 1999). Remote sensing technique relies on changes in the 

absorbance or reflectance of plants in response to pest attack. An instrument sensitive to 

specific wave lengths of radiation is used to detect such changes. Remote sensing in 

conjunction with ‘3S’ technique can help in achieving three-dimensional real time visualization 

of insect pest populations (Wang et al., 2003). 

Imagery provided by remote sensing satellites could be utilized in identifying pest affected 

areas and intensity of pest damage. This could be particularly useful for pests which produce 

visible symptoms of crop damage over large area e.g. hopper burn symptoms in paddy, blacking 

of cotton leaves caused by sooty mould growing on honey dew secreted by aphid and whitefly, 

etc. Similarly, satellite data have also been used to identify areas of vegetation capable of supporting 

desert locusts. Further, such data can also find application in studying the effect of environmental 

changes on build-up, long distance migration and flight behaviour of air-borne pests. 

The Australian Centre for Remote Sensing (ACRES) has introduced a new service to 

provide satellite data for real time application. The STAR (Speedy Transmission After 

3

Reception) service provides access to digital satellite data on various aspects which includes 

monitoring of pest infestations (Thankappan, 2001). 

The difficulty, apart from clouds, is to be able to relate pest and crop events on the 

ground to the pictures obtained. 

The Distance Diagnostics through Digital Imaging project enhances the ability of the 

University of Georgia Cooperative Extension Service to evaluate and propose solutions for 

agricultural problems, including plant diseases and pests, through the use of digital imaging 

and the World Wide Web. Imaging stations consisting of computers, digital cameras, 

microscopes and image-capture devices have been deployed in 94 county offices and in 3 

diagnostic labs. 

To date the Distance Diagnostics Through Digital Imaging System has exceeded 

expectations. There is abundant documented evidence of instances where DDDI has facilitated 

timely diagnosis or identification and intervention, preventing what could have potentially 

been individually (within a particular field) catastrophic crop or personal losses. As system 

use expands and familiarity increases, ever more utility seems to become evident. 

Acoustic and other tools : Sensors which can detect the sounds of hidden insects like 

wood borers, termites, stored grains pests, etc are finding applications in the advanced 

countries. Similarly, portable X-Ray machines are being employed for detection of insects 

attacking forest trees. 

Electronic nose : In Oregan (USA), electronic devices programmed for detecting 

particular odour or smell are being evaluated. One of these devices, Cyranose 3201, a portable 

electronic nose, has shown good promise in determining stink bug damage by external 

properties. The volatile compounds given off by sink bugs were identified and E-nose was 

trained to identify stink bugs’ (presence) smell prints. There was a strong correlation (R2 = 

0.95) between the number of stink bugs in a sample and the Cyranose sensor’s response 

(Henderson et al., 2006). 

CROP LOSS ASSESSMENT 

Historical perspective : Zadoks (1981) identified three periods in the history of concern 

about crop loss assessment : exploratory, emergency, and implementation. Zadoks and 

Koster (1976) reported that German Korn in 1880 was the first to stress the importance of 

using crop loss assessments for scientific and managerial purpose. Later on different 

countries like Sweden, Netherland and Prussia began to assess losses. The world’s first 

plant protection service started its work in the Netherland in 1899. The exploratory period 

came to an end with the 1914 International Phytopathological Conference in Rome. 

The periods of the two World Wars was the emergency period in which international 

exchange of commodities was hampered. Such situation coupled with droughts and famine 

caused food shortages resulting in loss of human life. 

The implementation period was first initiated by the phytopathologist E.C. Large (1950) 

in the United Kingdom. However, international interest on this aspect was stimulated by 

Food and Agriculture Organization (FAO) symposium on crop losses held in 1967 in Rome, 

which was organized by L. Chiarappa and J. Vallega (FAO, 1967). 

Work on crop loss methodology was strengthened by two publications produced under 

the aegis of FAO (Chiarappa, 1971, 1981). 

Pest infestations often have adverse effect on yield. Therefore, it becomes essential to 

accurately estimate the potential role of each agent in reducing yields so that based on their 

incidence the potential losses could be predicted. The understanding of the mechanisms 

4

which are involved in quantitative and qualitative crop losses could help in formulating 

appropriate strategies to minimize them. 

Basic crop loss terminology (after Zadoks, 1985) 

Yield : A crop’s measurable economic production. 

Injury : Any visible and measurable symptom caused by a harmful agent. The damage 

function translates injury into damage. 

Damage : Any reduction in quantity and/or quality of yield. The loss function translates 

damage into loss. 

Loss : The reduction in financial return per unit area due to harmful agents. 

Therefore, the assessment of crop losses due to insect pests is of important from the 

following points of view: 

1. For proper planning of research. For example, if the mechanisms of crop yield are known, 

research can be directed toward increasing yields by reducing the effect of pests on 

yield and yield quality, increasing crop resistance to pests, reducing pest attack by 

forecasting pest outbreaks. 

2. For defining economic status of a pest species so that relative importance of different 

pests can be ascertained. 

3. For establishing economic threshold and economic injury levels. 

4. For evaluating crop varieties for resistance to insect-pests. 

SUGGESTED READING 

Chiarappa, L. (ed.) 1971. Crop Loss Assessment Methods. FAO Manual on the Evaluation 

and Prevention of Losses by Pests, Diseases and Weeds. Commonwealth Agricultural 

Bureaux, Famham Royal, United Kingdom. 

Chiarappa, L. (ed.) 1981. Crop Loss Assessment.Supplement 3. Commonwealth Agricultural 

Bureaux, Famham Royal, United Kingdom. 

Southwood T R E (1978). Ecological Methods, with particular reference to the Study of 

Insect Populations. 2d ed. Chapman and Hall. London. 524 p. 

Thankappan, M. 2001. Access to satellite data for time-critical applications STAR and 

SPOTLITE. First Australian Geospatial Information and Agriculture Conference, Sydney, 

Australia, July 17-19, 2001. pp. 497-506. 

Wang, Z.J., Zhang, A.B. and Li, D.M. 2003. Applied approaches and progress in the use of 

remote sensing techniques in insect ecology. Entomological Knowledge 40 (2) : 97-100. 

Zhai, B.P. 1999. Tracking angels: 30 years of radar entomology. Acta Entomologica Sinica 

42 (3) : 315-326. 

http://oregonstate.edu/dept/nurserystartap/onnpdf/onn130601.pdf 

http://ohioline.osu.edu/hyg-fact/3000/pdf/pp401-02.pdf 

http://www.clemson.edu/precisionag/stink bug.pdf 

5

INSECT' NOMENCLATURE, IDENTIFICATION, 

CLASSIFICATION AND THEIR 

ROLE IN STRENGTHENING PEST DIAGNOSTICS 

Sucheta Khokhar 

Dean, College of Agriculture 

CCS Haryana Agricultural University, Hisar-125004, India 

Amongst animals the insects are most dominant and diverse group on the earth, which 

appeared 250 years ago. Insects are presumed to constitute about three-fourth of all living 

animals on earth. They fill many niches in both terrestrial and aquatic ecosystems; and a 

good number of them are celebrated pests of agricultural, medical and veterinary importance. 

Existing knowledge on insect biodiversity is poor and no one knows exactly how many 

species of insects exist. Widely divergent estimates have been provided including up to 30 

million species (Erwin, 1982), 12.5 million (Hammond, 1992) and 5-15 million (Stork, 1997) 

and 1-1.5 million named and described species and countless species yet to be discovered 

(most of text books). 

No new order of insects has been identified since 1915. For the first time in 87 years 

(Klass et al., 2002), researchers have discovered an insect that constitutes a new Order of 

insects. The discovery of the new insect Order by Entomologist, Oliver Zompro, from Germany 

has been named Mantophasmatodea, which increases the number of insect orders to 31. 

Zompro noted that it resembles a cross between a stick insect, a mantid, and a grasshopper, 

nomenclatured Mantophasma zephyrum from Namibia (Fig. 1 & 2). The species is commonly 

known as Gladiators, Heelwalkers, Rock Crawlers or mantophasmids. 

Fig. 1 & 2. Adult, Mantophasma zephyra Zompro & Adis 

Members of the order are wingless and carnivorous even as adults, making them relatively 

difficult to identify. These creatures are inconspicuous, about 1–4 cm (0.4–1.6 in.) long, is 

carnivorous and nocturnal. It lives at the base of clumps of grass that in rock crevices. 

Still many species are to be recorded / discovered. But many established species are 

either already become extinct or at the verge of extinction or qualified as endangered (Table 

1) as per IUCN (International Union for Conservation of Nature) and more information can be 

collected from the Red list page - http://www.iucnredlist.org/ so that they can be protected. 

6

Table 1. International Union for Conservation of Nature (IUCN) Status Categories 

Extinct Species not definitely located in the wild during the past 50 years. 

Endangered Taxa in danger of extinction and whose survival is unlikely if the 

causal factors continue operating. 

Vulnerable Taxa believed likely to move into the Endangered category in the 

near future if the causal factors continue operating. 

Rare Taxa with small world populations that are not at present ‘Endangered’ 

or ‘Vulnerable’, but are at risk. 

Indeterminate Taxa known to be ‘Endangered’, ‘Vulnerable’, or ‘Rare’ but where 

there is not enough information to say which of the three categories 

is appropriate. 

Significant progress has been made in the field of taxonomy and biology as well as in 

Insects control. Correct identification of an insect, its systematic position and knowledge of 

its relationships with other species are of paramount importance in insect control. The role 

of nomenclature is to provide labels or names for the taxonomic categories in order to facilitate 

communication among biologists. The name of an animal should be such that it should 

provide instantly the known information about the particular taxon. Every name has to be 

unique because it is the key to the entire literature relating to this species or higher taxon. 

If several names have been given to the same taxon, normally priority decides the validity of 

the same. Henceforth, the valid rules of zoological nomenclature are contained in an 

authoritative document entitled, “International Code of Zoological Nomenclature”. The 

preamble of the code (ICZN) says, “The object of the code is to promote stability and 

universality in the scientific names of animals and to ensure that each name is unique, 

widespread, universal, stable and distinct”. Nomenclature thus is the language of zoology 

and rules of nomenclature are its grammar. It is essential that the general principles of 

zoological nomenclature be familiar to all zoologists, whether they are systematists or 

involved in applied fields of the entomology. 

Species are groups of interbreeding natural populations that are reproductively isolated 

from other such groups. Cryptic/Sibling Species: Pairs or groups of closely related species 

which are reproductively isolated but morphologically identical or nearly so. Conspecific: A 

term applied to individuals or populations of the same species. Semispecies: The component 

species of superspecies; populations that have acquired same, but not yet all, attributes of 

species rank i.e. borderline cases between species and sub species. Superspecies: A 

superspecies is a monophyletic group of closely related and largely or entirely allopatric 

species. The validity of the name of a taxon is governed by Law of Priority which says that 

the oldest available name applied to it is the valid, provided the name is not invalidated by 

any provision of the code or has not been suppressed by the Commission. The main limitation 

is that a name that has remained unused as a senior synonym in the literature for more than 

fifty years is to be considered a forgotten name i.e. nomen oblitum. A single specimen 

designated or indicated as the ‘the type” by the original author at the time of the publication 

of the original description is known as the Holotype and rest of the specimens of the type 

series are called as Paratypes. In nomenclature, when one of two or more identical but 

independently proposed names for the same or different taxa are available, called homonyms. 

7

The junior homonym is always rejected and replaced by another name. While each of two or 

more different independently proposed names for the same taxon are known as synonyms 

constituting the chronological list of the scientific names which have been applied to a given 

taxon, including the dates of publication and the authors of the names. 

The scientific names species and subspecies are usually adjectives and expressed as 

binomial and trinomial, respectively. These are always printed in italics if written or typewritten 

they are under scored. The scientific names are followed by the name of the author 

i.e. describer of the species or subspecies which is not italicized e.g. Papilio ajax Linnaeus. 

If the author’s name is in parenthesis it means that the author described under one genus 

initially i.e. Heliothis but later on it was shifted to another genus i.e. Helicoverpa. Similarly, 

author of the species may be written by full name and may not be abbreviated to mere first 

letter or few letters of the name. And if year is to be incorporated with scientific name of a 

species then a comma is always used in between the author’s name and year e.g. Hemilea 

bipars Hardy, 1959. But this type of citation is optional and may be expressed completely 

once in the text of any manuscript and subsequently genus can be donated by first capital 

letter following by species name e.g. H. armigera. The species name should always be 

written with its respective genus but if author is not sure about the identity of species or he 

is to indicate more than one species under a genus he may express as Papilio sp. or Papilio 

spp., respectively. The species may be named after a country’s name or geographical 

distribution, the ending will be –ana (e.g. americana) or-ensis (e.g. hisarensis). If named 

after person/s the word will end with –ilorum e.g. flecheri (man); smithorum (men), flecherae 

(woman); smitharum (women). A number or numerical adjective or adverb forming a part of a 

compound name is to be written in full as a word and united with remainder of the name e.g. 

septumpunctata, not 7-punctata. 

Care must be taken in citation of the common names of insects in the text. Most common 

names of insects refer to large groups such as subfamilies, families suborders or orders 

rather than to individual species e.g. the name “tortoise beetle” refers to the species in the 

subfamily Cassinae of the family Chrysomelidae; and the term ‘beetle’ refers to the entire 

Coleoptera or ‘thrips’ to whole Thysanoptera. The names ‘fly’ and ‘bug’ are used for insects 

in more than one order and when ‘fly’ of an insect’s name is written separately like black fly, 

horse fly etc. they all belong to the order Diptera and are often spoken as the ‘true’ flies. But 

when the ‘fly’ is written together with the descriptive word e.g. scorpionfly, sawfly, stonefly 

or dragonfly, the insect belongs to some order other than Diptera i.e. they belong to orders 

Mecoptera, Hymenoptera, Plecoptera and Odonata, respectively. Henceforth, the ‘true’ bugs 

of order Hemiptera are named with ‘bug’ as a separate word damsel bug, stink bug or water 

bug while for insects in other orders the ‘bug’ of the name is written together with the 

descriptive word e.g. mealybug, sowbug or ladybug. Snodgrass (1956) stated a rule to express 

common names of insects, “If the insect is what its name implies, write the two component 

words separately otherwise run them together”. The aphislion is not a lion, silverfish is not a 

fish and honey bee is pre-eminently a bee which produces honey should always be written 

as honey bee and not honeybee. 

The economic importance of the insects puts increasing pressure on the taxonomists 

for identification and classification. Taxonomy or systematics is the science of classification 

of organisms. Classification is the arrangement of the individuals into groups and groups 

into a system in which the data about the kinds determine their position in the system and 

8

thereafter reflecting their position. Both taxonomy and classification and the other aspects 

dealing with kinds of organisms and the data accumulated about them, are included in 

systematics, which is the general term that covers all aspects of the study of kinds. Therefore, 

Systematics, which is derived from Latinized Greek word systema used by Linnaeus deals 

with the study of the kinds and diversity of organisms, their distinction, classification and 

evolution. Nevertheless, in actual practice it is rather difficult to completely dissociate each 

of these under discrete compartments. These three terms have been used alternately on the 

same subject by various workers. 

For using all the information in the action programmes (IPM etc.), the taxonomist acts 

as a catalyst who allows the control of the pests through manipulation of their various attributes 

as well as in the management of our environment in the cheapest and more successful way. 

Biosystematics thus provides the basic tools for characterizing the entities that we study, 

the species of organisms. Classifications: is the ordering of organisms into groups on the 

basis of their relationships, that is, of their associations by contiguity, similarity or both. 

Taxonomy: is the theoretical study of classification, including its bases, principles, 

procedures and rules. Taxonomy, like classification, has also been used to designate the 

end products of the taxonomic process. Systematics, in other words, is used to understand 

the evolutionary history of life on Earth. All these terms are often used interchangeably. The 

process of classification is totally different from that of identification. In classification we 

undertake the ordering of populations and group of populations at all levels by inductive 

procedures; in identification we place individuals by deductive procedures into previously 

classes. For the identification of an insect, any of the six ways may be adopted i.e. (1) to 

get specimen identified by an expert, (2) by comparing it with labeled specimens in a 

collection, (3) by comparing it with images and illustrations, (4) by comparing it with 

descriptions, (5) by the use of an analytical key, (6) by a combination of two or more of 

these procedures. Of these, first two methods may not always be available. Similarly, 

illustrations, etc. may not be included with description of an organism, and the best procedure 

is to use the suitable key. 

Biological systematics or Biosystematics is the science through which life forms are 

discovered, identified, described, named, classified and catalogued, with their diversity, life 

histories, living habits, roles in an ecosystem, and spatial and geographical distributions 

recorded. 

In recent years a taxonomist is not only to describe, identify and arrange organisms in 

convenient categories but also to understand their evolutionary histories and mechanisms. 

The systematics/ taxonomic studies involves a series of characters which can be grouped 

as: (1) Morphological characters, general external morphology, special structures (e.g. 

genitalia), internal morphology, embryology, karyology (and other cytological differences); 

(2) Physiology characters, metabolic factors, serological, protein and other biological 

differences, body secretions, gene sterility factors; (3) Ecological characters, habitats and 

hosts; (4) food, seasonal variations, parasites, host reactions; (5) Ethological characters, 

courtship and other ethological isolation, other behaviors patterns; and (6) Molecular genetic 

characters, isozymes, nucleic acid sequences, gene expression and regulation. The 

informations gathered on these aspects provide better basis for understanding an organism 

and relationship with the environment as well as other organisms. 

9

The biological classification may belong to any of the types viz., (1) Phenatic 

classification: The taxa are classified either on the basis of few characters or overall 

characteristics, without direct reference to phylogeny; (2) Natural classification: The 

classification is based on the natural characters of taxa. In this system of classification, the 

organisms are placed into as many as groups and sub groups as are in similarities and 

dissimilarities; (3) Cladistic or Phylogenetic Classification: Cladistic classification is 

exclusively based on phylogenetic branching. It includes an attempt to map the sequence of 

phyletic branching through a determination of characters that are shared primitive 

(plesiomorphic) and that are shared-derived (apomorphic); (4) Envolutionary classification: 

It is based on the evolutionary relationship of organisms, not just their phylogeny. This 

classification provides foundations of all comparative studies in biology through the degree 

of genetic similarity existing between organisms and the phylogenetic sequence of events 

in their history; and (5) Omnispective Classification: All the readily available features of 

the organisms are considered but only those are used for classification purpose which are 

helpful in establishing groupings and distinctions. This is currently used as majority of the 

taxonomists. 

A hierarchy is a systematic frame work for zoological classification with a sequence of 

classes at different levels in which each class except the lowest includes one or more 

subordinate classes. An hierarchy does involve principles of priority and to the extent that 

these principles are derived from real or natural relationships among organisms hierarchic 

classification is natural. About 18 categories are recognized in the hierarchy of classification 

of an organism (Mayr et al.,1953) e.g. Kingdom, Phylum, Subphylum, Class, Subclass, 

Cohort, Superorder, Order, Suborder, Infraorder, Superfamily, Family, Subfamily, Tribe, Genus, 

Subgenus, Species, Subspecies. The name of some systematic categories like family group 

of an insect have standard endings and hence can always be recognized as referring to a 

particular sort of group e.g. superfamily names end in-oidea, family names as –idea, 

subfamily as -inae and tribe –ini (e.g. Pentatomoidea, Pentatomidae, Pentatominae & 

Pentatomini). 

A key is a systematic framework for zoological classification (generally used for 

identification to the exclusion of other purposes) with a sequence of classes at each level of 

which more restricted classes are formed by overlap of two or more classes at the next 

higher level. A key involves no principle of priority and has a purely arbitrary conventional 

sequence keys are universally considered artificial. There are many types of Keys, namely, 

Indented keys, Tabulated keys, Dichotomous– bracket keys/ simple non- bracket key, 

Pictorial keys, Circular keys, Box-type keys. Most of taxonomic literature or text books 

refer to dichotomous/analytical keys. The characters of an organism are expressed in 

couplets which are numbered 1 and 1’ 2 and 2’ and so on. Thus, each step leads to another 

step and it alternatives, until a name is reached. One’s success in running an insect through 

a key depends largely on an understanding of the characters used. 

The keys, which have been constructed in majority of the text books, for the identification 

of agriculturally important insects belonging to different orders, generally include the following 

diagnostic characters : 

1. Collembola : Body shape (elongate or globular); antennal length (longer or shorter than 

head); abdominal segmentation (distinct or indistinct); length of furcula (mucro short or 

long). 

10

2. Odonata : Head shape (transversely elongated or not), size of eyes (large & often 

contiguous dorsally or small & widely separated); shape of fore and hind wings (hind 

wings wider at base or both pairs petiolated at base); position of wings at repose (held 

horizontal on sides of body or held together above body); distinct wing venation with 

nodus (beyond or before mid-length of wing) and stigma (small or elongated or absent or 

abnormal); body shape of naiad (robust or delicate); gills of naiads (concealed rectal 

gills or differently shaped and sized caudal gills). 

3. Dermaptera : Eyes (well developed or absent); wings (present or apterous); cerci 

(sclerolized forceps–like or not horny, may be delicate or hairy); shape and size of IItarsal 

segment (cylindrical or lobed beneath or heart-shaped). 

4. Isoptera : Fontanelle (present or absent) in all castes; shape and size of pronotum of 

workers and soldiers (saddle-shaped or flat, with or without anterior lobe, narrower or 

broader than head); reticulation of wings (often reticulate or slightly reticulate); lobe of 

hind wings (well developed or absent); tarsi (5- or 4- segmented). 

5. Orthoptera : Body (elongate or thickset); antennal length and modifications (about as 

long or longer/shorter than body, filiform/clavate/serrate/pectinate); wings (fully developed 

or brachypterous or apterous) fore wings (tegmen type or vestigial); stridulatory apparatus 

(present or absent); fore and hind legs (modified or normal); tarsal segments (1 to 4segmented); 

tympanal organ (present on fore tibiae/at base of abdomen or absent); 

empodium (present or absent); pronotum (normal or extended backwards to cover 

abdomen); ovipositor well developed (elongated, leaf-like/needle-like or short); 

unsegmented cerci (small or elongated). 

6. Hemiptera : Habitat (aquatic, semiaquatic or terrestrial); head constricted behind eyes 

or not constricted; antennae 4-or 5-segmented, antennal length (as long as or longer/ 

shorter than head), antennae exposed or concealed in cavities, ocelli present (paired) or 

absent; labium 1 to 4- segmented; membrane of hemelytra (distinct or indistinct), when 

distinct, with five/less veins or many veins; corium entire or divided into cuneus and/or 

embolium, fore legs (simple or raptorial); tibiae (spinose or not); tarsi 2- or 3- segmented; 

scutellum small or large; connexivia of abdominal tergites (upto 6 or 7 segments) visible. 

7. Homoptera : All body tagmata (well developed and distinct or degenerated structurally); 

antennae small or long (concealed or exposed), arising on sides of head or on frons of 

head; ocelli (2 / 3 or none); pronotum extending backward or not, over abdomen; legs 

(simple or modified); tarsi 1 – or 2- segmented, (with single or paired claws); wings well 

developed or apterous; fore wings when present opaque or transparent, covered or not 

covered with whitish powder, hind wings as large as or much smaller than fore wings, 

forewing with numerous or few veins, RS present or absent; cornicles (present or absent); 

all females oviparous or only sexual females oviparous and parthenogenetic females 

viviparous. 

8. Neuroptera : Body and wing (densely hairy or not) antennae variably modified (filiform, 

moniliform, pectinnate or clavate), antennal length (as long as head and thorax together 

or longer than body); ocelli (present or absent); prothorax (normal or elongate); fore legs 

raptorial or normal; wing venation reduced or more complete, hind wings equal to fore 

11

wings (in length and width) or greatly elongated and ribbon-like, cross-veins in both 

pairs of wings (numerous or few). 

9. Lepidoptera : Mandibles (functional or non-functional);lacinia of adults (well developed 

or not), galeae (haustellate or not); antennae variously modified (clavate, setaceous, 

pectinate, bipectinate, filiform etc.); wing-coupling apparatus (present or absent), wings 

(broad with well-developed venation or wings narrow or cleft into plumes with or without 

venation or reduced venation); tympanal organ (present or absent), when present may be 

in metathorax or abdomen; tibial spurs (present or absent); female (with 1 or 2 genital 

openings). 

10. Diptera : Ocelli(3) present, may be absent or indistinct; antennae (short or elongated), 

variously modified (aristate, setaceous, plumose, pilose, stylate etc.);mandibles either 

absent or modified as stylets in adults; thorax with or without v-shaped suture on 

mesonotum; wing venation of fore wings (variable). 

11. Hymenoptera : Abdominal attachment with thorax (broad or constricted); antennae 

insertion (below eyes and below apparent clypeus or between eyes, well above the 

clypeus); flageller length (very long or not abnormally long); hind margin of pronotum 

(almost straight or deeply emerginate behind); wings (well developed or absent or may 

be very rudimentary), wings when present with distinct venation and closed cells, fore 

wings (with or without distinct pterosigma); hind femur (with or without trochantellus). 

12. Coleoptera : Habitat (terrestrial or aquatic); clypeus extending or not, laterally in front 

of antennal insertions; eyes not divided or completely divided into dorsal and ventral 

parts; antennae variously modified (filiform, moniliform, setaceous, pectinate, serrate, 

lamellate etc.); metasternum (with or without groove); shape of fore coxae (conical or 

spherical), hind coxae (immovably fixed or not immovable fixed to metasternum, dividing 

or not dividing the first visible abdominal sternite). 

Hence it may be concluded that the first step while underlying any scientific work 

pertaining to an insect pest is to know its correct identity and systematic position. When it 

is correctly identified, the available information on the biology and habits of that insect, its 

most vulnerable stage, the appropriate time and the most suitable method or methods to 

control it can be referred to. The knowledge and understanding of the ecological facts, both 

biotic and abiotic, influencing the population of an insect pest are necessary for planning 

the proper strategy for controlling the pest. 

No scientific programme like IPM or ecological surveys etc. could be carried out without 

the most painstaking identification of all species of economic significance. Even the 

experimental biologists have learnt to appreciate the necessity of sound and solid 

identification. There are great numbers of genera with two, three or more very similar species. 

The information on the systematic position, morphology, physiology, genetics and types of 

development of insects together with the due consideration of their classification and biologies 

is essential for an entomologist to apply the appropriate control measure. It is impossible to 

speak of any taxon under consideration of any study or to think lucidly about it unless it is 

named. Even the enforcement of the conservation laws, a knowledge of the species involved 

must be had. 

12

A mistake in the identity of the host may result in the complete loss of years of work and 

large amounts of money. For instance, a pest of oriental origin is mis-identified as a closely 

related to European species, the search for natural enemies in Europe and their collection, 

rearing and colonization for biological control, might prove utterly futile. Due to the 

misidentification of cassava mealybug (Phenacoccus manthoti) in Africa the parasitoids 

collected from wrong host species were unable to breed on the pest species, resulted in 

heavy loss of money and delay in the implementation and success of the proper control 

programme against the same species of mealybug (Norgaard, 1988). 


Erwin, T. 1982. Tropical forests: their richness in Coleoptera and other arthropod species. 

Coleopterists Bull. 36 : 74-75. 

Danks, H.V. 1988. Systematics in support of Entomology. Ann. Rev. Ent. 33 : 271-296. 

Hammond, P. 1992. Species inventory. pp. 17-39. In : B. Groombridge (ed.) Global 

Biodiversity: Status of the Earth’s Living Resources. Chapman and Hall London. 

Klass, K.D., Zompro, O., Kristensen, N.P. and Adis, J.2002.‘Mantophasmatodea: A New 

Order with Extant Members in Afrotropics’. Science 296,1456. 

Mayr, E. ; Linsley, E.G. and Usinger, R.L. 1953. Methods and Principles of Systematic 

Zoology. Mcgraw Hill, New York, 328 pp. 

Norgaard, R.B. 1988. The biocontrol of cassava mealybug in Africa. American J. Agri.Econ. 

10 : 366-371. 

Sailor, R.I. 1969. A taxonomist’s view point of environmental research and habitat 

manipulation. Proc. Tall. Timbers Conference on Ecological Animal Control by habitat 

management No.1. Published by Tall Timbers Res. Station, Tallahasse, Florida. 

Snodgrass, R.E. 1956. The Anatomy of the Honey Bee. Cornell University Press; Ithaca, 

New York, 70 pp. 

Stork, N.E. 1991. The composition of the arthropod fauna of Bornean lowland rainforest 

trees. J. Trop. Ecol. 7 : 161-180. 

13

A SYSTEMATIC APPROACH TO DIAGNOSING 

PLANT DAMAGE 

Ram Singh 

Department of Entomology, 


Precise diagnosis must be made before corrective action can be taken. Probability of 

correct diagnosis based on only one or two clues or symptoms is low. Similarities of symptoms 

produced on the same plant by completely different factors frequently make the use of 

symptoms alone inadequate. 

Factors causing plant damage can be grouped into two major categories : 

Living factors: living organisms such as pathogens (fungi, bacteria, viruses, nematodes) 

and pests (insects, mites, mollusks, rodents...). 

Nonliving factors: mechanical factors (i.e. breakage, abrasions, etc); physical, 

environmental factors (extremes of temperature, light, moisture, oxygen, lightning); and, 

chemical factors (chemical phytotoxicities, nutritional disorders, etc). 

I. DEFINE THE PROBLEM 

A. Plant identification and characteristics. Establish what the “normal” plant would 

look like at this time of year. Describe the “abnormality”: Symptoms & Signs. 

B. Examine the entire plant and its community. Determine the primary problem and 

part of the plant where initial damage occurred. 

II. LOOK FOR PATTERNS: On more than one plant? On more than one plant species? 

A. Non-uniform damage pattern-(scattered damage on one or only a few plant species) 

is indicative of living factors (pathogens, insects, etc.). 

B. Uniform damage pattern over a large area (i.e. damage patterns on several plant 

species) and uniform pattern on the individual plant and plant parts indicates nonliving 

factors (mechanical, physical, or chemical factors). 

III. DELINEATE TIME-DEVELOPMENT OF DAMAGE PATTERN : 

A. Progressive spread of the damage on a plant, onto other plants, or over an area with 

time indicates damage caused by living organisms. 

B. Damage occurs, does not spread to other plants or parts’’ of the affected plant.’ 

Clear line of demarcation between damaged and undamaged tissues. These clues 

indicate nonliving damaging factors. 

IV. DETERMINE CAUSES OF THE PLANT DAMAGE : 

A. Distinguish among living factors 

1. Symptoms and signs of PATHOGENS. 

2. Symptoms and signs of INSECTS, MITES, and other ANIMALS. 

B. Distinguish among nonliving factors 

1. MECHANICAL FACTORS 

14

2. PHYSICAL FACTORS 

a. Temperature extremes 

b. Light extremes 

c. Oxygen and moisture extremes 

3. CHEMICAL FACTORS 

a. Analyze damage patterns in fields and other plantings. 

b. Injury patterns on individual plants. 

c. Pesticide-pollutant phytotoxicities – damage patterns. 

d. Nutritional disorders -key to nutritional disorders. 

If we suspect that it is a living damaging factor, we will look for signs and symptoms to 

distinguish between pathogens and insects. If the accumulated evidence suggests that it is 

a pathogen, we will seek evidence to distinguish among fungal, bacterial, viral pathogens 

and nematodes. If the evidence indicates the damaging factor is an insect or other animal, 

we will seek further evidence to distinguish between sucking and chewing types. 

If evidence indicates that the damage is being caused by a nonliving factor, we will 

seek further evidence as to whether the initial damage is occurring in the root or aerial 

environment. We will then attempt to determine if the damage results from MECHANICAL 

FACTORS, from extremes in PHYSICAL FACTORS ( i.e. environmental factors such as 

extremes of temperature, light, moisture, oxygen), or from CHEMICAL FACTORS (i.e. 

phytotoxic chemicals or nutritional 

disorders). Once we have identified the 

plant and limited the range of probable 

causes of the damage, we can obtain 

further information to confirm our 

diagnosis from reference books, 

specialists such as plant pathologists, 

entomologists, horticulturists, and/or 

laboratory analyses. 

SYMPTOMS AND SIGNS OF INSECTS, 

MITES AND OTHER ANIMALS 

INSECTS 

The location of the feeding damage 

on the plant caused by the insect’s 

feeding, and the type of damage 

(damage from chewing or from sucking 

mouth parts) are the most important 

clues in determining that the plant 

damage is insect-caused and in 

identifying the responsible insect 

(Fig.1). 

FEEDING HABITS 

Chewing insects eat plant tissue 

such as leaves, flowers, buds, and 

twigs. Indications of damage by these Fig.1. Plant infested by a variety of insects 

15

insects is often seen by uneven or broken margins on the leaves, skeletonization of the 

leaves, and leaf mining. Chewing insects can be beetle adults or larvae, moth larvae 

(caterpillars), and many other groups of insects. The damage they cause (leaf notching, leaf 

mining, leaf skeletonizing, etc.) will help in identifying the pest insect. 

Injury by Chewing Insects 

Perhaps the best way to gain an idea of the prevalence of this type of insect damage is 

to try to find leaves of plants with no sign of insect chewing injury. Armyworms, grasshoppers, 

hairy caterpillars, beetles are common examples of insects that cause chewing injury. 

Chewing Damage or Rasping Damage: 

Entire leaf blade consumed by various caterpillars, canker worms, and webworms. Only 

tougher midvein remains. 

Distinct portions of leaf missing. 

Leaf surfaces damaged: “Skeletonization” of leaf surface. Slugs, beetle larvae, pearslug 

(pear sawfly larvae), elm leaf beetle, and thrips. 

Leaves “rolled”: Leaves that are tied together with silken threads or rolled into a tube 

often harbor leafrollers or leaftiers, i.e. omnivorous leaftier. 

Leaf miners feed between the upper and lower leaf surfaces. If the leaf is held up to the 

light, one can see either the insect or frass in the damaged area (discolored or swollen 

leaf tissue area), i.e. citrus leafminer, pea leaf miners. 

Petiole and leaf stalk borers burrow into the petiole near the blade or near the base of 

the leaf. Tissues are weakened and leaf falls in early summer. 

Twig girdlers and pruners, i.e. vine weevil and twig girdling beetle. 

Borers feed under the bark in the cambium tissue or in the solid wood or xylem tissue. 

Damage is often recognized by a general decline of the plant or a specific branch. Close 

examination will often reveal the presence of holes in the bark, accumulation of frass or 

sawdust-like material or pitch, i.e. mango stem borer. 

Root feeders, larval stages of weevils, beetles and moths cause general decline of plant, 

chewed areas of roots, i.e. root weevil, white grubs. 

Feed on the growing points or plants and thus retard the growth as in the case of the 

grapevine flea beetle Scelodonta strigicollis. 

Feed on the leaves and defoliate the plants causing reduction in assimilative leaf area 

and thus hinder growth. The semilooper caterpillar on castor, the red hairy caterpillar on 

groundnut, and the slug caterpillar on mango and castor are some examples. 

Make small holes in the leaves by feeding. The flea beetle on radish and sunnhemp 

cause this type of damage. 

Feed on a layer of surface tissue of leaf (e.g. larvae of the diamond back moth on cabbage 

and cauliflower) or superficially on the surface tissue (e.g. grubs and adults of the beetles 

Epilachna spp. on brinjal and bittergourd). 

Leaves riddled with large holes of irregular shape and size due to feeding (e.g. cabbage 

semilooper Trichoplusia ni). 

16

Roll up the leaves and feed within as in the larvae of Sylepta derogata and S. lunalis on 

cotton and grapevine, respectively. 

The larvae feed on the bark of the plants or trees living concealed in a protective covering 

of frass and excreta in a silken web as in the case of the bark caterpillar lndarbela 

tetraonis on moringa, curry leaf, rain tree etc. 

Cut the stem of tender plants at the time of germination. The surface weevil Attactogaster 

finitimus attacks similarly the seedlings of cotton raised under the rainfed conditions in 

the black soil tract of TirunelveIi district in South India. 

Feed on the flower buds and flowers and cause reduction in production. The larvae of 

Maruca testulalis web the flower buds and flowers on redgram and feed on them. The 

adults of the blister beetle on red gram and sesbania and cetoniid beetle on rose feed on 

the flower buds and petals. 

Nibble and cut off ear heads as in the case of rice grasshoppers. 

Eat partially on the grains and give chalky appearance as in the case of the damage inflicted 

by the larvae of Helicoverpa armigera to the ears of sorghum and finger-millet (ragi). 

Sucking insects insert their beak (proboscis) into the tissues of leaves, twigs, branches, 

flowers, or fruit and then feed on the plant’s juices. Some examples of sucking insects are 

aphids, mealy bugs, thrips, and leafhoppers. Damage caused by these pests is often indicated 

by discoloration, drooping, wilting, leaf spots (stippling), honeydew, or general lack of vigor 

in the affected plant 

Injury by Piercing-Sucking Insects 

Another important method which insects use to feed on plants is piercing the epidermis 

(skin) and sucking sap from cells. Aphids, scale insects, squash bugs, leafhoppers and 

plant bugs are examples of piercing-sucking insects. 

Sucking Damage 

In addition to direct mechanical damage from feeding, some phloem-feeding insects 

cause damage by injecting toxic substances when feeding. This can cause symptoms which 

range from simple stippling of the leaves to extensive disruption of the entire plant. Insect 

species which secrete phytotoxic substances are called toxigenic (toxin-producing) insects. 

The resulting plant damage is called “phytotoxemia” or “toxemia”. 

Spotting or Stippling result from little diffusion of the toxin and localized destruction of 

the chlorophyll by the injected enzymes at the feeding site. Aphids, leafhoppers, and lygus 

bugs are commonly associated with this type of injury. 

Leaf curling or Puckering – More severe toxemias such as tissue malformations develop 

when toxic saliva causes the leaf to curl and pucker around the insect. Severe aphid 

infestations may cause this type of damage. 

Systemic Toxemia – In some cases the toxic effects from toxigenic insect feeding 

spread throughout the plant resulting in reduced growth and chlorosis. Psyllid yellows of 

potatoes and tomatoes and scale and mealy bug infestations may cause systemic toxemia. 

Most sucking insects attack the leaves of plants. A general chlorosis is caused by 

aphids and many of them cause ultimate withering and drying of the affected portions. 

17

Faint yellow speckling of leaves may be produced due to feeding as in the case of the 

castor whitefly and the coconut scale. 

Silvering or whitening of leaf surface due to removal of cell contents below the epidermis 

is the typical damage caused by thrips on crops like onion, groundnut, etc. White feeding 

spots are caused by tingid bugs like Stephanitis typicus on coconut and banana. 

Hopper burn or necrotic brown lesion is the typical injury produced by leafhoppers e.g., 

the cotton, castor leaf hoppers and white-backed plant hopper in paddy. 

Crinkling or curling of leaves is caused by insects like aphids, thrips and leafhoppers. 

Distortion of foliage and clustering of terminal shoots as in mealybug infestation on 

tender shoots of Gliricidia maculata. 

Proliferation of tissue around the site of feeding is sometimes produced e.g., whitefly 

Bemisia tabaci infestation on Achyranthes aspera. 

Premature shedding of developing fruits or drying of shoots as in scales and mealy bugs 

e.g., the San Jose scale on apple, the rose scale, etc. 

Premature fall of fruits as in citrus caused by the fruit sucking moths which pierce the 

rind of fruits. 

General (uniform) “stipple” or flecking or chlorotic pattern on leaf i.e. adelgid damage on 

spruce needles and bronzing by lace bugs. 

Random stipple pattern on leaf, i.e. leafhoppers, mites. 

Leaf and stem “distortion” associated with off-color foliage = aphids (distortion often 

confused with growth regulator injury), i.e. rose aphid, black cherry aphid, leaf curl plum 

aphid. 

Galls, swellings on leaf and stem tissue may be caused by an assortment of insects, 

i.e. aphids, wasps, midge, mossyrose gall wasp, poplar petiole gall midge, azalea leaf 

gall. 

Damaged twigs = split: Damage resembling split by some sharp instrument is due to 

egg laying (oviposition) by sucking insects such as tree hoppers and cicadas. Splitting 

of the branch is often enough to kill the end of the branch, i.e. cicada. 

Root, stem, branch feeders – general decline of entire plant or section of a plant as 

indicated by poor color, reduced growth, dieback. Scales, mealy bugs, pine needle scale. 

Injury by Internal Feeders 

Many insects feed within plant tissue during a part or all of their destructive stages. 

They gain entrance to plants either in the egg stage when the female thrust into the tissues 

with sharp ovipositors and deposit the eggs there, or by eating their way in after they hatch 

from the eggs. In either case, the hole by which they enter is almost always minute and 

often invisible. A large hole in a fruit, seed, nut, twig or trunk generally indicates where the 

insect has come out, and not the point where it entered. 

(a) Borers : When the larvae feed on the wood or pith of the plant or part of the plant 

which may be generally large enough to contain the body of the pest, they are referred to as 

borers. The larvae may bore into the terminal shoots and cause death of the shoots as in the 

case of the cotton bollworm, Earias spp. In the case of the rice stem borer and the sorghum 

18

stem borer, the larvae enter into the stem and cause death of the central shoots. An unique 

example of an adult beetle ‘borer is that of the coconut rhinoceros beetle, Oryctes rhinoceros, 

which bores into the unopened tender fronds biting the fibrous material. 

(b) Worms or weevils : They are borers in flower buds and fruits including nuts and 

seeds. The larvae bore into flower buds and cause shedding. Such larvae are usually called 

bud worms as in the case of the moringa budworm and jasmine budworm. The larvae may 

bore into the bolls, nuts, fruits or the seeds inside capsules. The cotton bollworms, the 

mango nut weevil, the pink bollworm of cotton, the brinjal fruit borer and the castor capsule 

borer come under this category. 

(c) Leaf miners : When the larvae, being very small, live in between the two epidermal 

layers of the leaves and feed on the food material inside, they are referred to as leaf miners. 

Some of the common examples are the citrus leaf miner, the cashew and mango leaf miner, 

and the buprestid leaf miner Trachys sp. on Barleria cristata. 

(d) Galls : In their immature and or adult stages certain insects are known to be 

responsible for the formation of special plant deformities known as galls and these galls 

provide shelter and food to the insect. The nutritious sap secreted inside the gall is either 

absorbed through the body surface or sucked by the mouthparts. Due to the formation of 

galls the growth of the plants may be impaired and setting of fruits, grains and seeds may 

be adversely affected. In many cases it may be observed that the galls are practically 

harmless to the plants. The galls may be simple as curling of leaves or simple enlargements 

of affected portions or of complex structures as in some galls produced by psyllid bugs. 

Mostly some species belonging to the families Cecidomyiidae, Cynipidae, Aphididae, 

Psyllidae and Aleyrodidae and the order Thysanoptera (thrips) are known to cause plant 

galls on the different parts of plants. Flower galls are produced by the midges (cecidomyiids), 

Contarinia sorghicola on sorghum and the blossom midge on mango. 

Gall insects sting plants and cause them to produce a structure of deformed tissue. The 

insect then finds shelter and abundant food inside this plant growth. Although the gall is 

entirely plant tissue, the insect controls and directs the form and shape it takes as it grows. 

Injury by Subterranean Insects 

Subterranean insects are those insects that attack plants below the surface of the soil. 

They include chewers, sap suckers, root borers and gall insects. The attacks differ from the 

above ground forms only in their position with reference to the soil surface. Some subterranean 

insects spend their entire life cycle below ground. In other subterranean insects, there is at 

least one life stage that occurs above the soil surface; these include wireworm, root maggot, 

pillbug, strawberry root weevil, and corn rootworm. The larvae are root feeders while the 

adults live above ground. 

Insects which are found in the soil live by feeding on the roots of plants and trees by chewing 

or boring or sucking the sap or forming galls. Many soil insects are host specific and most 

of them damage the crops in their larval stage as in wireworms, chafers, cutworms, flea 

beetles, etc., and only a few spend their life-cycle in the soil entirely. Some insects have 

several stages in the soil as in the root grub (Holotrichia sp.) of finger-millet (egg, larva and 

pupa in the soil). In some cases as in the fruit flies Dacus spp. of mango, bittergourd, etc. 

and the mango inflorescence gall midge only the pupae are found in the soil. The larvae of 

the soil pests may be found at different levels in the soil. Though the damage caused to root 

may vary depending on the species and crop affected, generally the attacked plants show 

stunting, discolouration and withering and death of the plants. The larvae may feed externally 

19

on roots as in wireworms, weevil grubs and chafers (white grubs) while in the case of the flea 

beetle Longitarsus belgaumensis the grubs bore or tunnel. Sometimes it may be seen that 

the seeds sown do not germinate as they have been eaten away by insects like ants in the 

soil. The tubers of the sweet potato crops in the fields are sometimes riddled with holes by 

the larvae of the weevil Cylas formicarius and the gelechiid moth Phthorimaea operculella, 

respectively. 

Injury to stored products 

In three ways the stored products are attacked by insects. 

It may be a continuation of a field attack as in sweet potato weevil and potato tuber moth. 

The eggs may be laid in the field itself and the damage may occur in storage as in 

redgram infested by the bruchid beetle. 

The infestation may continue from the material stored earlier and be carried over to fresh 

material stored later in a godown or storage house as in the grain weevil, Sitophilus 

oryzae, which infests single grains and the flour moth, Cadra cautella which webs together 

the grains with silken threads and feeds on them. Apart from this type of attack the 

occasional damage to food material in the stores by cockroaches may also be considered. 

INDIRECT EFFECTS OF FEEDING 

Making the harvest more difficult 

Heavy incidence of some pests on crops makes the harvest of the crop more difficult. It 

may be very difficult to harvest cabbage or Lab-lab pods infested heavily with aphids or 

kapas from cotton bolls damaged by bollworms. 

Causing contamination and loss of quality of produce 

Due to insect attack the final produce may show loss of quality by reduction in nutritional 

value or in marketability. In the case of cardamom the berries infested by thrips become poor in 

quality due to scaly patches on the rind. Other examples are sweet potato tubers riddled with 

holes by the weevil Cylas formicarius, brinjal fruits bored by larvae of Leucinodes orbonalis, 

amaranthus leaves skeletonised by larvae of Hymenia recurvalis and cabbage riddled with shot 

holes by the semilooper Trichoplusia ni. 

Disseminate plant diseases 

Insects are responsible for spreading many plant diseases caused by bacteria, fungi 

and viruses. Though bacteria and fungi have alternative methods of dispersal, many plant 

viruses are mostly dependent upon their insect vectors for dissemination. 

INJURY BY OTHER METHOD 

Injury by egg-laying 

Insects take a great deal of care in laying their eggs at the right place so that the young one 

will have enough food material for its development, and thus survive. By the act of oviposition 

sometimes a few species of insects have been observed to inflict injury to crops. It is a wellknown 

fact that the periodical cicada, also known as “seventeen year locust”, splits the wood 

severely on twigs of one year old growth for egg laying as a result of which the portion beyond 

that dries up. In the case of cow bugs (Membracidae), they insert their eggs in rows into the 

tissue of the tender stem and thus cause injury. The grapevine stem girdler, Sthenias grisator, 

which attacks a number of plants in South India, chews off the twig by ringing and then inserts 

the eggs into the distal portion of the twig so that the larvae may have wood in a suitable condition 

of moisture and decay for its development. 

20

Use of plant parts for making nests 

Sometimes parts of plants are removed by insects for the construction of their nests 

though they do not feed on them. A striking example is the removal of rather neat circular 

pieces of foliage from plants like rose, redgram, etc. by the leaf cutter bee Megachile 

anthracina. Similarly, tropical leaf cutting ants are known to strip off leaves from plants and 

trees and carry them to their nests. In the case of the red ant, Oecophylla smaragdina the 

nest is constructed on the tree itself by webbing together a few leaves and is a source of 

nuisance especially in the orchards. 

Injurious insects being carried from one plant to another 

Ants and some other kinds of insects though they are not injurious to crops by themselves, 

often carry to other plants such injurious forms as aphids, mealy bugs, etc. They care for and 

protect these insects for they feed on the honey dew excretion of these pests. This mutual 

dependency of two organisms upon each other is termed mutualism. 

Use of Plants for Nest Materials 

In addition to laying eggs in plants, insects sometimes remove parts of plants for the 

construction of nests or for provisioning nests. 

Insects as Disseminators of Plant Diseases 

Insects may spread plant diseases in the following ways : 

By feeding, laying eggs or boring into plants, they create an entrance point for a disease 

that is not actually transported by them. 

They carry and disseminate the causative agents of the disease on or in their bodies 

from one plant to a susceptible surface of another plant. 

They carry pathogens on the outside or inside of their bodies and inject plants 

hypodermically as they feed. 

The insect may serve as an essential host for some part of the pathogens life cycle, and 

the disease could not complete its life cycle without the insect host. 


David, B. and Kumaraswami, T. 1975. Elements of Economic Entomology, Popular Book 

Depot, Madras, pp. 536. 

Metcalf, C.L. and Flint, W.P. 1967. Destructive and Useful Insects their Habits and Control. 

Tata McGraw-Hill Publishing Company, New Delhi. pp. 1087. 

Pedigo, L.P. and Rice, M.E. 2009. Entomology and Pest Management. PHI Learning Private 

Limited, New Delhi. pp. 784. 

21

METHODS OF ESTIMATING CROP LOSSES 

DUE TO INSECT-PESTS 

Pala Ram 



Three groups of people namely, farmers, industry and the government agencies, need 

information on insect pest loss. The farmers need the information to decide whether or not 

to use control measures, industry for profit governing and decision making, and the government 

for general welfare of the whole community. The evaluation of pest damage is helpful in pest 

management in several ways. It helps in defining the economic status of a pest species, in 

establishing economic threshold and economic injury levels, in estimating effectiveness of 

control measures, in allocating funds for research and extension in plant protection, in 

evaluation of varieties, and in knowing relative importance of different pests. Pest damage 

assessment involves, i) discovery of damage, ii) determination of pest identity and first 

appraisal of its seriousness, iii) determination of the effect on the plant and on overall 

production, involving some research on the relation between pest abundance and effect, 

and; iv) measurement of its local and national effect on production and management with 

some estimate in economic terms (Young, 1975). 

1. Pest population and damage relationships : 

One of the fundamental concepts of integrated pest management is that each pest species 

has a definable relationship in terms of damage to the plant or animal host that it attacks. 

This relationship is often referred to as the damage curve which is determined relative to 

yield loss. Two types of relationships can generally occur between pest attack and yield. 

Type one relationship (Fig. 1) occurs where the pest is a vector of disease, or where it 

attacks the grain late in the crop, or where crop tolerance and compensation is limited. Type 

two relationship (Fig. 2) occurs where the pest attacks at the vegetative stage of the crop 

and the crop’s innate tolerance (e.g. more tillers than it can take through to maturity) or 

compensation mechanisms result in no loss of yield occurring, up to a threshold level of 

pest attack. Yields at a wide range of infestations are needed, to describe the full relationship 

and to know how yield is affected at low and high infestation rates. There are several methods 

for obtaining these figures (Chiarappa, 1971; Pradhan, 1964; Walker, 1983). 

Fig. 1 Fig. 2 

22

Following experimental techniques are generally applied for assessing crop losses caused 

by insect pests : 

Comparison of yield in fields with different degrees of pest infestation under natural 

conditions : 

Naturally occurring infestations often are used to give a range of infestation or damage 

in single plant, plot or field. The yield is determined per unit area in different fields with 

different degrees of pest infestation and correlation between the crop yield and degree of 

infestation is worked out to estimate yield. A study under natural infestation of stem borers 

in maize in Kenya, under recommended farm practices, estimated the crop losses at 36.9 

% (Mulaa, 1995). Extrapolation of these data may again be dangerous, since crop losses 

measured under these conditions might not be representative of actual farmers’ conditions. 

Therefore, only systematic surveys under natural infestations and under farmers’ conditions 

can produce more reliable crop loss estimates for a given area. Groote (2001) used farmers’ 

(often subjective) estimates of losses under natural infestation and the incidence of infestation 

to estimate maize yield losses for each of Kenya’s major agro-ecological zones. The yield 

loss was estimated to be 12.9 %. The advantages of using natural infestations are i) crop 

yield responses to attack are exactly as they are in the field, ii) there are no side effects 

from chemicals, iii) there is no interference, and iv) pest distribution is natural. A disadvantage 

is that there is less experimental control, and hence more variation due to differences in 

climate, soil, and other pests or diseases and often a less useful range of infestation rates. 

Exclusion of pests by mechanical barriers, allowing direct comparison of yield: 

The crop is grown in cages made-up of nylon, metal or cotton cloth. These cages exclude 

the pests from crop. Pest infestation may be artificially increased or decreased to establish 

known pest densities. Eggs, larvae, or adults are placed in or on the crop in cages in order 

to keep pest numbers constant. Metal cages may be used to retain cutworm populations, 

soil beetle larvae and to exclude rodents. Natural infestation should be removed by hand, by 

trapping or with a non-persistent pesticide, and further infestation prevented. The yield under 

such enclosures is compared with that obtained from the infested crop under similar 

conditions. A number of studies in eastern Africa have demonstrated a strong relationship 

between maize yield and damage caused by artificial infestation of stem borers. Ajala and 

Saxena (1994) studied the relationship among damage parameters such as foliar damage, 

dead hearts (%), stem tunneling, morphological parameters such as plant height and number 

of ears per plant, and their influence on grain, after artificial infestation of three-week-old 

maize plants, with 30 first instars. Reduction in the number of ears harvested due to larval 

infestation was found to be the primary cause of grain yield loss, mainly due to stem tunneling 

of the plants. Yield losses were estimated to fall between 34 and 43 %. Gayawali (2005) 

estimated yield loss in soybean due to leaf roller (Apoderus cyaneus Hope) by introducing 

adults into nylon cages installed at the central rows of each plot just after germination of 

soybean. Insects were maintained at population density of 25, 50 and 100 per m2. 

Percentages of yield losses were 36.2, 45.2, and 58.0 during vegetative and 37.5, 48.5 and 

66.0 during reproductive stages from the insect population of 25, 50 and 100, respectively. 

The advantages of artificial infestation are that the infestation can be controlled and 

other factors removed. The disadvantages are i) pest material for infestation must be collected 

at the appropriate stage in the field, ii) infestation by hand can be tiresome and laborious, 

iii) timing infestation in relation to crop growth stage or climate may be critical, iv) cages 

may affect plant yield as well as the pest population inside them, v) cages may affect yield 

by changing light or air flow, but they have little effect on temperature or humidity. 

23

Exclusion of pests, or reduction of their populations by the use of pesticides, allowing 

direct comparison of yield : 

Pesticides have been commonly used in loss assessment experiments to establish 

different infestation levels of insects, rodents, birds and other pests, weeds, and plant 

diseases. Pesticides may also be used with artificial infestation, caged experiments, and 

other methods. The crop is protected from pest damage through the application of pesticides. 

The yield of the treated crop is compared with the one which has been subjected to normal 

infestation. Losses due to a complex of pests can be assessed using specific pesticides, 

method of application, or method of reaching the pests. For example, Bacillus thuringiensis 

or viruses may affect only lepidopterous larvae while acaricides only mites. Systemic 

insecticides for sucking insects, granules and seed dressing for soil insects, spray on stems 

only for insects that attack the stem and insecticidal bait only for pests that eat it such as 

fruit flies or cutworms. Basavaraju et al. (2009) estimated yield losses due to various pests 

in potato using pesticide check method. They reported that aphids, Myzus persicae caused 

3-6 per cent, Spodoptera litura 4-8 per cent, potato tuber moth, Phthoremaea operculella 6- 

9 per cent and mite, Polyphagotarsonemus latus, 4-26.80 per cent yield loss. Balraj Singh 

et al. (1983) maintained different levels of infestation of mustard aphid on raya crop by using 

endosulfan spray. They reported that at population levels of 400, 300, 200, 100 and 50 

aphids per plant yield reduction was 54.8, 51.8, 19.7, 13.2 and 2.5 per cent, respectively. 

Nabirye et al. (2003) conducted studies to assess the effect of legume flower thrips 

(Megalurothrips sjostedti) injury on cowpea grain yields by using various insecticide spray 

regimes for obtaining different thrips densities per experimental unit and use of exclusion 

cages in the field to confine defined numbers of thrips populations. A significant negative 

relationship (y=”0.011x+1.77) was observed in the field studies between thrips densities and 

cowpea grain yields. 

The advantage of using pesticides is that populations of individual pests can be controlled. 

The disadvantages are i) pesticides may reduce crop yield if phytotoxic or may enhance it 

as with carbofuran, ii) unknown pests may be affecting yield, and pesticides may affect 

them as well as the main pest, iii) pesticides may kill or repel parasitoids, affecting the pest 

population, and iv) pesticides also contribute to inter-plot interference and drift or runoff may 

affect untreated pests and plants on nearby plots, v) trials with pesticides may also give 

biased results when they are deliberately conducted in high-infestation areas. 

Simulated damage studies : 

Pest damage may be simulated by artificial damage. Many researchers have tried to 

simulate pest injury by removing or injuring leaves or other parts of plant. Sabra et al. (2005) 

estimated yield loss due to Ostrinia nubilalis in maize by simulating damage. Eight weeks 

after plantation, damage of O. nubilalis was simulated through five different treatments, in 

addition to the control (healthy plants), by cutting the stem at the: tassel, tassel + one leaf, 

tassel + two leaves, tassel + three leaves and at ear level. They reported that simulated O. 

nubilalis damage reduced grains yield with about 4.11- 35.14 per cent according to the sort 

of damage. Mean weights of grains were 9.724, 9.066, 7.733, 7.467 and 6.577 gm/100 ears 

for the different sorts, respectively and 10.141gm/100 ears for the control. The corresponding 

percents of yield reduction were 4.11, 10.61, 23.74, 26.37 and 35.14%, respectively. Sandhu 

(1974) conducted simulated damage studies on spotted bollworm, Earias vittella on cotton. 

In de-topped cotton plants (simulated damage of spotted bollworm) shedding of fruiting bodies 

was 83.58 per cent as compared to 71.42 per cent in control plants resulting in 12.82 and 

22.10 per cent reduction in yield of seed cotton, respectively. The advantage of this method 

is that the amount of damage can be exactly controlled. A disadvantage is that the time of 

damage in relation to climate and crop growth stage is often critical. 

24

Pest control economics : 

Pest population assessment and decision making are among the most basic elements 

in any integrated pest management (IPM) programme. Bioeconomics, the study of the 

relationships between pest numbers, host responses to injury, and resultant economic losses 

forms the basis of assessment and decision making (Pedigo, 1996). The relationship between 

density of pest population and the profitability of control measures is expressed through 

threshold values namely, economic injury level and economic threshold. Economic injury 

level (EIL) concept given by Stern et al. (1959) still forms the basis of most IPM programmes 

in use today. Economic damage, economic injury level, and economic threshold collectively 

form the concept of EIL. 

Economic damage : Economic damage is the most elementary of the EIL elements, 

being defined by Stern et al., (1959) as “the amount of injury which will justify the cost of 

artificial control measures”. 

Damage boundary or damage threshold : The damage boundary is the lowest level of 

injury that can be measured (Pedigo et al. 1986). This level of injury occurs before economic 

loss. Expressed in terms of yield, economic loss is reached at the gain threshold, and the 

gain threshold is beyond the damage boundary. For high value commodities, the damage 

boundary may be very close to the gain threshold. 

Economic Injury Level : Another of the basic elements, the economic injury level, was 

defined by Stern et al. (1959) as the "lowest population density that will cause economic 

damage". The EIL is the most basic of the decision rules; it is a theoretical value that, if 

actually attained by a pest population, will result in economic damage. Therefore, the EIL is 

a measure against which we evaluate the destructive status and potential of a pest population. 

Economic threshold or action threshold : The economic threshold (ET) differs from 

the EIL in that it is a practical or operational rule, rather than a theoretical one. Stern et al. 

(1959) defined the ET as “the population density at which control action should be determined 

(initiated) to prevent an increasing pest population (injury) from reaching the economic injury 

level.” Although measured in insect density, the ET is actually a time to take action, i.e., 

numbers are simply an index of that time. Some workers refer to the ET as the action 

threshold to emphasize the true meaning of the ET. 

Determination of threshold values : 

For determination of EIL, values such as cost of treatment per acre, and value of crop 

per acre are required. The following procedure is followed for determination of EIL: i) to work 

out cost-benefit ratios, ii) to establish yield-infestation relationship by regression analysis, 

and iii) to work out EIL by method of Pedigo (1989). The gain threshold is an important 

measure as it represents a basic margin for determining benefits of management and 

establishing treatment decision parameters (Pedigo, 1989). The gain threshold is a basic 

break-even analysis and can be calculated as a first step when determining the EIL (Pedigo 

et al., 1986). The gain threshold is expressed in amount of harvestable yield; when cost of 

suppressing insect injury equals money to be gained from avoiding the damage. The gain 

threshold is expressed as : 

Gain threshold = Management costs (Rs/ha)/Market value (Rs/kg) = kg/ha. 

For example, in mustard crop if total cost of pesticidal application for maintaining the 

level of 50 aphids/plant is Rs. 900 per ha and mustard seed is marketed for Rs. 30 per kg, 

the gain threshold would be: Rs. 900/Rs.30 = 30 kg per ha. This means that the increase in 

yield, or gain, has to be 30 kg per ha for this pesticide application to be economic. 

EIL = gain threshold/loss per insect. 

25

So from the above example, if the gain threshold is 30 kilograms per hectare and the 

damage per aphid is 1.5 kg per hectare, then the EIL would be:30/1.5=20+50 (basic level)=70 

aphids per plant. So if a field is sampled and aphid population is more than 70 aphids per 

plant an appropriate intervention should be used. If there are fewer than 70 aphids per plant, 

then we can save money by not intervening as the gain threshold is not high enough to make 

intervention economically feasible. 

EIL can be also be calculated using full EIL equation which incorporates the following : 

EIL=C/VIDK 

where, 

C = Cost of management activity per unit of production (Rs./ha) 

V = Market value per unit of yield or product (Rs./ton) 

I = Crop injury per insect (Per cent defoliation/insect) 

D = Damage or yield loss per unit of injury (Ton loss/% defoliation) 

K = Proportionate reduction in injury from pesticide use 

For example calculate EIL in terms of pest population/ha with following figures 

C = Management cost per unit area = Rs.6,000/- per ha 

V = Market value in Rs./unit product = Rs.2,000/ton 

I = Crop injury/pest density = 1% defoliation/100 insects 

D = Loss caused by unit injury = 0.05 ton loss/1% defoliation 

K = Proportionate reduction in injury by pesticide application = 0.8 (80% control) 

Thus, 

EIL = C/VIDK = 6000/2000x0.01x0.05x0.8 

EIL = 7500 insects/ha or 0.75 insects/ sq. meter 


Dhaliwal, G. S., Arora, R. and Dhawan A. K. (2004): Crop losses due to insect pests in 

Indian agriculture: an update. Indian Journal of Ecology, 31 : 1-7. 

Pedigo, L. P. and Rice, M. E. 2009. Entomology and Pest Management. Sixth Edition. PHI 

Learning Private Ltd., New Delhi. pp. 784. 

Pedigo, L. P., and Buntin, G. D. 1994. Handbook of Sampling Methods for Arthropods in 

Agriculture. CRC Press, Boca Raton, FL. 616 pp. 

Pedigo, L. P., and Higley, L. G. 1992. A new perspective of the economic injury level concept 

and environmental quality. American Entomologist 38 : 12-21. 

Pedigo, L. P., Hutchins, S. H. and Higley, L. G. 1986. Economic injury levels in theory and 

practice. Ann. Rev. Ent. 31 : 341-368. 

Poston, F. L., Pedigo, L. P. and Welch, S. M. 1983. Economic injury levels: reality and 

practicality. Bull. ent. Soc. Am. 29 : 49--53. 

Pradhan, S. 1964. Assessment of losses caused by insect pests of crops and estimation of 

insect population. In : Entomology in India, Entomological Society of India, New Delhi, 

pp 17-58 

Southwood, T. R. E., and Norton, G. A. 1973. Economic aspects of pest management 

strategies and decisions. Ecol. Soc. Aust., Mem. 1 : 168--184. 

Stern, V. M., Smith, R. F., Bosch, R. van den, and Hagen, K. S. 1959. The integrated control 

concept. Hilgardia 29 : 81--101. 

26

SIGNIFICANCE OF INSECT PEST-LOSS RELATIONSHIPS 

R. K. Saini 



The loss suffered by a crop is a function of the pest population, behaviour of the pest and 

the biological characteristics of the crop plant. Loss is caused by feeding or during the 

process of oviposition. It may be in the form of loss of production capacity, loss of productive 

capacity, loss of stand, direct damage, product contamination and loss in storage etc. The 

type of loss by insect pest is influenced by several factors including the organ of the pest 

used to cause damage, part of the plant attacked, amount of destruction per unit time and 

damage in relation to insect numbers. 

Based on feeding behaviour, a pest may be external feeder or internal feeder. The pest may 

damage subterranean parts (roots) which may result in wilting of plants; stems of herbaceous 

plants; trunks and main branches of trees; twigs and buds, leaves, flowers and fruits. 

Definition of loss due to pests 

Crop loss implies yield reduction which may be expressed as the percentage of reduction 

in potential yield in the absence of pests m. If yield in the presence of pests is y, then 

yield loss (w ) = (m - y) × 100 

m 

It is often difficult to establish the maximum potential yield in the absence of pests on 

which to base the calculation of yield reductions, and hence benefits. The type of farming, 

whether peasant or research, and the amount of inputs are important. The decision depends 

on the purpose: to answer a research problem, to assess the economic benefits of a 

development project, or to evaluate the relative importance of various pests, weeds, or 

diseases. 

Type and units of yield 

Yield is usually the economic product harvested, either the primary product or a natural 

or processed constituent of it. Quality or marketing grade also may be important. Wheatley 

(1974) divided pest attacks into those with high or low incidence and high or low severity of 

damage. Cases of low incidence or low severity in a high-value crop are sometimes called 

cosmetic damage-when a small pest attack causes great loss in crop value. 

Yield and loss also can be expressed in terms of energy equivalent, assessed on inputs 

of fertilizer, pesticide, and fuel used in producing the yield. Monetary value at the farm gate, 

in the market, or on board (if exported) is commonly used. But prices often vary rapidly with 

supply and demand. Tax, subsidy and support prices, exchange rate, and even shadow 

prices may be used. For subsistence crops, the price of an alternative crop or an opportunity 

price may have to be calculated. Using yield quantity avoids these difficulties. 

Mechanism of yield reduction due to pests 

The effect of pests and other causes of yield reduction in a crop is best seen as a 

system or flow chart. In an individual plant, inputs of radiation, water, and nutrients enter the 

leaves and roots, and are translocated to a sink. From the sink they are partitioned and 

carried by translocation to the reproductive parts (grain, fruit, or storage organs such as 

cassava roots or sugarcane stems) — the yield. 

27

The system is plastic and dynamic. Yields of individual parts or modules such as tillers 

or spikelets interact and compensate to give the plant yield (Harper 1977). Plant yields 

interact and compensate to give the crop yield. Reduction in one part of the system can be 

compensated for by an increase in another. If values are put on the inputs and the rates of 

change, we have a crop production system that can be modeled: the effects of different 

inputs (such as a pest attack) can be simulated and yield predicted. Such production system 

models are being developed for many crops. 

Pests may affect crop yields in the following ways : (Walker P. T. ,1977) 

Establishment, if germination and early growth of plants are affected by beetle larvae, 

cutworms, armyworms, crickets, termites, etc. 

Photosynthetic area, if lost due to damage by leaf-eating, mining, or leaf-folding pests, 

aphids, and bugs, or by shading of leaves with honeydew or sooty mold. 

Uptake of water or nutrients, if reduced by root pests, beetle larvae, borers, termites, 

etc. 

Translocation, if interrupted from leaves and roots to stores and to yielding parts by stem 

borers, cutworms, scales, mealybugs, rodents, etc. 

Storage organs, if stems, roots, and tubers are damaged by borers, tuber moth larvae, 

beetle larvae, rodents, etc. 

Reproductive parts, if seeds and grain are damaged by midges, beetles, bugs, caterpillars, 

locusts, rodents, and birds, or fruit by moths, fruit flies, bugs, hoppers, scales, etc. Loss of 

quality is important. 

Secondary loss, if secondary pests or diseases enter primary damage lesions or diseases 

are introduced by insect vectors. 

Spoilage and down grading, if a product becomes unacceptable in the market because of 

holes, spots, insect parts, rodent excreta, etc., even if there is no loss of weight or quality. 

Harvesting and processing, if pest attack makes crops difficult to harvest or process, 

such as fire-ants in cashew, moth webbing, sticky cotton lint, mealybug mold on citrus, etc. 

Pest-loss relationship : infestation and yield (Source : P. T. Walker ,1977). 

How yield varies with changes in pest infestation or damage is important in predicting 

the yields, and hence the benefits, that will be obtained with pest control measures. The 

relationship is useful in evaluating economic action thresholds, pest densities, or damage 

levels that cause different amounts of yield loss. The regression may be simple, ignoring 

many other factors, or complex, incorporating individual relationships for several plant parts 

or the effects of several different pests or other causes of loss (Fig. 1). The relationship may 

change with time of attack, stage of pest, method of assessment, growth stage of the crop, 

or general growing conditions (Bardner and Fletcher 1974; Southwood and Norton 1973; 

Walker 1983a,b). 

A straight-line relationship (Fig. 1A) 

When one individual or group of pests damages one plant or one plant part (e.g. a midge 

infesting one floret), a proportional decrease in yield may occur with an increase in infestation. 

No compensation by the plant or by parts of it occurs, and there is no threshold level below 

which yield is not reduced. 

28

A sigmoid or S-shaped relationship (Fig. 1B) 

If the relation between y and i is examined over a full range of values of i , there is often 

a threshold value below which no reduction in yield occurs, mostly due to compensation by 

unattacked parts or by clean plants for attacked ones. The result is a sigmoid curve, with a 

central, straight-line section, and a final flattening at high values of i when some yield is 

often produced, Rate of loss b changes with the value of i. Sometimes only the convex 

half of the curve is found, when attack is early, on vegetative parts, leaves, etc., and 

compensation can occur. Sometimes only the concave curve is found, when attack is on 

reproductive parts, such as grain, and compensation is impossible. It is difficult to fit a 

formula to a sigmoid curve, unless summed and a probit transformation of the normal 

probability distribution of yields is used to linearize the relationship, as with dosage-mortality 

curves. 

A logarithmic relationship (Fig. 1C) 

Yield may be related to the logarithm or a power of the number of pests, where their 

effects are multiplicative rather than additive. Examples are mobile or rapidly multiplying 

pests, such as whiteflies or aphids. There may be compensation for attack. Transformation 

of pest density, for example ( i ) to log ( i + l), may be needed. 

Rapid yield loss at low rates of infestation (Fig. 1D) 

Small numbers of pests sometimes can cause a disproportionate reduction in yield, for 

example, if the pest is a disease vector, as in the effect on rice yield of brown planthopper, 

the vector of grassy stunt disease (Dyck 1974). Cosmetic damage, such as scale on citrus, 

is another example. Gradients of disease attack are discussed by Thresh (1976). 

An increase in yield (Fig. 1E) 

Low infestations can cause an increase in yield; yield falls with a further increase in 

infestation. Pest attack may stimulate growth and yield. Destruction of the growing point of 

tillering plants such as rice, or of plants with continuous production of fruiting points such 

as cotton, will cause a yield increase if growing conditions are favorable. If there is too much 

foliage and not enough light, reduction of leaf area by leaf-eating pests may increase light 

falling on the plants and increase yield. Pest attack also may increase drying at maturity, 

increasing the sugar content of sugarcane. Or pests may selectively attack higher yielding 

plants, giving a positive relationship between infestation and yield. The subject is reviewed 

by Harris (1974). 

No relation between infestation and yield (Fig. 1F) 

Sometimes, unaccountably, no relationship is found. This may result from trying to 

average highly variable data, from not having a full range of infestations (such as no zero 

attack) or from some other effect. Variation should be reduced by altering plot or sampling 

design, by stratifying sources of variation into types of farming, soil, or other cause of variation, 

or by improving the techniques of measuring infestation, control, or yield. 

A model for predicting yield from the amount of pest infestation can be improved by 

including factors that affect pest population. Biocontrols such as parasitoids or disease, 

temperature as degree days, and rainfall can be used. For example, loss of forage due to 

grasshoppers has been forecast from grasshopper development (Hewitt and Onsager 1982). 

That prediction depended on temperature summation (Gage and Mukerji 1971). Such models 

must take into account the distribution and probability of attack and a possible nonlinear 

response of the pest to a controlling factor (Feldman and Curry 1982). 

29

Fig. 1. Pest-loss relationship (Source : P. T. Walker, 1977). 

A. A straight-line relationship 

B. A sigmoid or S-shaped relationship 

C. A logarithmic relationship 

D. Rapid yield loss at low rates of infestation 

E. An increase in yield 

F. No relation between infestation and yield. 

Duration of pest attack 

Crop yield reduction depends on the duration of pest attack as well as pest density. This 

can be quantified by relating yields to bug days, the number of pests multiplied by the 

number of days they are present. This method has been used for brown planthopper. 

30

Mixed crops 

In multiple cropping, two or more crops are often grown together—at once, overlapping, 

or serially during the season. One way to relate yield ( y ) to pest attack is to express the 

different crops (a and b) in terms of the pure stand of one crop (a) on the same area— a land 

equivalent ratio (LER) (Zandstra et a1 1981): If different crops are grown for different periods 

of time, an area time equivalent ratio is useful (Hiebsch 1978). That brings in the proportion 

and time each crop occupies an area in the total crop pattern. The effect of pests on yield is 

measured by the same techniques as in single rops, with and without pests, etc. 

Missing plants and plant interaction and compensation 

The distribution of a pest attack in a field affects the relationship between yield and 

attack. In a spaced-out attack with missing plants unattacked plants next to a missing or 

attacked plant usually yield more than if all are unattacked, due to the removal of competition 

for light, water, or nutrients. The compensation depends on the degree of competition resulting 

from plant spacing, weeds, and growing conditions. 

Often, some pest attack can be tolerated without loss of yield. If attacked or missing 

plants occur in large groups however, compensation cannot occur. Yield falls rapidly with a 

rise in infestation. Compensation can be measured by examining the yield of an unattacked 

plant surrounded by different arrangements of attacked plants—for example, groups of five 

(pentads) of potato plants (Killick 1979) or in cylinders of influence around tobacco plants 

attacked by cutworm (Shaw 1980). The effect of missing plants is seen in the hyperbolic 

relationship between plant weight and population, the 3/2 thinning rule (Solbrig 1980), and 

the simple model of Hardwick and Andrews (1983). The difference between actual and expected 

yield of attacked potatoes has been used to show how well different plants can compensate 

for attack (Adams and Lapwood 1983). Different causes of loss interact so much and yield 

response is so variable, one is really dealing with a response surface. Multivariate methods 

are the only accurate way to look at all the factors involved. Ecology and weed science are 

providing some answers (Begon and Mortimer 1986). 

Distribution of loss 

The statistical distribution of crop loss over a wide area in both space and time is obviously 

related to pest distribution. Distributions are often nonrandom, either because climate or 

crops often occur in aggregated groups or because they occur at regular intervals. If the 

distribution were known, it would be easier to predict crop losses and the need for pesticides. 

Tanner (1962) found similar loss distribution curves when the summed frequency of losses 

as percentages of total loss were plotted against multiples of the average loss. Curves can 

be linearized by taking logs. In this way, the actual and expected curves can be compared 

to explain why differences in loss distribution exist (e.g. because of different sowing times 

[Walker 1965]). 


Adams J M (1964). A review of the literature concerning losses in cereals and pulses since 

1964. Trop. Sci. 19 : 1-28. 

Ahrens C, Cramer H H, Mock M, Peschel H (1983). Economic aspects of crop losses. Proc. 

10th Int. Congr. Plant Prot. Brighton, 1 : 65-73. 

31

Bardner R, Fletcher K E (1974). Insect infestations and their effects on growth and yield of 

field crops. Bull. ent. Res. 64 : 141-160. 

Chiarappa L, ed. (1971). Crop Loss Assessment Methods : FAO Manual on the Evaluation 

and Prevention of Losses by Pests, Diseases, Weeds. Food and Agriculture Organization 

and Commonwealth Agricultural Bureaux International, Slough, UK. 123 p. 

FAO-Food and Agriculture Organization (1977) Analysis of an FAO survey of post-harvest 

crop losses in developing countries. Rep. AGPP: MISC./27. Rome, Italy. 147 p. 

Harris P (1974). Possible explanations of plant yield increases following insect damage. 

Agroecosystems. 1 : 219-225. 

Headley J C (1972b). The economics of agricultural pest control. Ann. Rev. Ent. 17 : 273. 

Khosla R K (1977). Techniques for assessment of losses due to pests and diseases of rice. 

Indian J. agric. Sci. 47 : 171-174. 

Mumford J D, Norton G A (1984). Economics of decision-making in pest management. Ann. 

Rev. Ent. 29 : 157-174. 

Mumford J D, Norton G A (1987). Economics of integrated pest management. Pages 191- 

200. In : Crop Loss Assessment and Pest Management. P. S. Teng, ed. APS Press, St. 

Paul, Minnesota. 

Norton G A (1976b). Pest control decision-making, an overview. Ann. appl. Biol. 84 : 444- 

447. 

Pedigo L, Hutchins S H, Highley L G. Economic injury levels in theory and practice. Pimentel 

D, ed. (1981) Pest Management in Agriculture. 1. CRC Press, Boca Raton, Florida. 

Pinstrup-Andersen P, de Londoño N, Infante M (1976). A suggested procedure for estimating 

yield and production losses in crops. PANS. 22 : 359-365. 

Reed W (1983). Crop losses caused by insect pests in the developing world. Proc. 10th Int. 

Congr. Plant Prot. Brighton. 1 : 74-79. 

Stem V M (1973). Economic thresholds. Ann. Rev. Ent. 18 : 258-280. 

Walker P T (1977). Crop losses : some relations between infestation, cost of control and 

yield in pest management. Environ. Entomol. 5 : 891-900. 

Walker P T (1983a). The assessment of crop losses in cereals. Insect Sci. Applic. 

4 : 97-104. 

32

PROCEDURE FOR COLLECTING PLANT AND 

INSECT SAMPLES FOR PROBLEM DIAGNOSIS 

K. K. Mrig and S. S. Sharma 

Department of Entomololgy, 


Most plants are prone to attack by various insect pest and plant disease organisms. 

Pest outbreaks and diseases must be identified accurately to enable their efficient 

management. 

Basic requirements for collecting, preserving and submitting plant, insect and disease 

samples 

(A) Collecting plant samples : 

It is important to gather the best plant samples possible and to record all pertinent 

background information for the diagnostician. Following are general guidelines for collecting 

plant samples. 

1. Examine the entire plant for symptoms 

Plants may be affected by one or more pathogenic microorganisms or pests, although 

they may also have an abiotic disease that does not involve a plant pathogen. Affected 

Plants often display a range of symptoms—visual signs of the infection or pest damage. 

2. Collect several plant specimens 

A single plant sample may not be enough to allow a correct diagnosis of the problem; 

several plant samples showing the range of symptoms may be needed. If possible, select 

samples with various stages of disease development (early and late stages). but submitting 

excessive amounts of leaves or soil should be avoided. 

How to collect data in the field? 

Identifying the sampling sites 

(a) Tagging the site 

Mark sampling sites in the field whenever possible, even if you do not intend to return to 

the same site so that if a specimen or observation taken islost or destroyed, you would be 

able to revisit the site if needed. Remember to choose tags that will survive a variety of 

weather conditions, and use a pencil or ink that does not smear when wetted to label the 

tags. Options for marking the site include: 

spray-painting a mark 

placing sticks with a bright tassel or tag, particularly where a pest has been completely 

removed (such as weeds), but only when the stick or marker will not interfere with the 

management of the site, such as getting caught in harvesting equipment 

tying a tag or tassel to a plant stem or branch. 

(b) Recording site details 

The location and unique identifying details of each site need to be recorded in a notebook. 

These details may be entered using a standard form that can be used for each site. 

33

Describing the sampling site would include information such as a GPS reading, a unique 

number, distances from visual cues (e.g. 20 metres from roadside), number or nearest number 

of plant in a row (e.g. tenth tree in third row from the northeastern corner), or any distinguishing 

topographical features (e.g. edge of a ravine, in a ditch). 

What data to record in the field 

The most important tool you will have with you in the field will be your notebook and 

notes. In your notes you would record any information that could otherwise be forgotten, 

such as the dates of surveying, the weather at the time, the site details, the names and 

contact details of the local people involved. 

Notebooks with carbon paper duplicate pages can be very useful when recording 

information to accompany a specimen taken. In this way, the details are written once only 

but you then have a permanent record in your notebook and a copy to be kept with the 

specimen. 

Designing a form 

The simplest way to record data is to design a form that allows for recording all the 

information that you intend to collect. 

A simple way to save a lot of time is to work out ahead of the survey how the data will be 

stored and to design your form so that it is easy to transfer the information to the storage 

system. When designing a form, you could include the following : 

observer’s name 

field site number or name 

sampling site number or name 

targeted pest names—common and scientific 

time and date 

brief description of weather conditions 

locations, such as by GPS readings, of sampling sites 

description of habitat (e.g. aspect, vegetation, soil type) 

scale/population density categories that could be ticked 

symptoms of the pest or host 

pest life stage or state (e.g. larvae, pupae, adults for insects; anamorph/teleomorph state 

for fungi; seedling, budding, senescent, first flush for plants) 

caste of colonial insects surveyed, such as of termites, ants and some wasps 

behavioural notes on possible vectors (e.g. ‘insect ovipositing on fruit’ or ‘insect restingon 

plant leaf ’) area or length of plot or transect assessed 

cross-reference to pest example in a pest photo library 

colour of identifying features, such as of flowers 

any quarantine measures applied at the field site, such as hygiene measures 

treatments applied to site 

additional comments 

34

Units for data 

Data are normally reported in terms of a unit of measure, usually the number of pests 

per unit area. The number might be a direct count of the pests or could be a scale of 

intensity of the pest that is recorded. The area examined might be per tree, fruit, field, crop, 

kilometre, quadrat, sweep of a net, trap etc. For example: number of shoots attacked per 

plant, number of trees affected as compared with the total number of trees examined. 

Use of scales and scores 

In some cases where the pest is numerous, or particularly for symptoms of plant 

pathogens, whole numbers of pests are not possible or useful. Instead, a scale of cover of 

the host or a standardised measure of the pest could be used. Scales are semi-quantitative 

as the scale intervals can be wide and may not be consistent in their range. 

3. Preserving plant samples 

After collecting the samples, do not expose them to direct sunlight. Keep them cool and 

do not allow them to dry out or cook. Place samples in plastic bags in the shade or in a 

cooler until they are ready for delivery to the plant clinic. Leaves may be pressed between 

the pages of a book or magazine or wrapped in tissue. 

(A) Collecting insect samples 

Collect whole insects in good condition. 

Collect as many insect stages as possible: eggs, larvae, pupae, and adults. 

Place the insects in 70 per cent isopropyl alcohol immediately. Keep moths and 

butterflies intact in small containers or wrapped with plastic or paper. 

Spiders should be collected alive, dropped into hot (180 degrees F) water, and 

transferred to 70 per cent isopropyl alcohol after cooling. 

If the insect was causing plant damage, include a plant specimen showing evidence 

of the plant injury. 

Avoid touching insects with fingers : Some insects can injure humans. Handling 

insects can also cause damage to their bodies that may prevent their identification. 

Collect different life stages of the insect : Sometimes insects cannot be properly 

identified unless a certain life stage is present. For example, adults may be needed 

for correct identification. 

Collect multiple specimens : Collect several specimens of the insect. Time of day 

matters. Many leaf-feeding insects (such as caterpillars) may hide from predators 

during daylight hours. It may be necessary to capture insects during twilight in the 

evening or early morning. 

(B) Preserving insect specimens 

(i) Most insects : Roaches, termites, bugs, beetles, flies, wasps, ants, maggots, 

spiders, etc. should be immersed in isopropyl (“rubbing”) alcohol, which kills and 

preserves them. 

(ii) Mites, scales, aphids, thrips : Send these in alive on some of the affected foliage 

or stems, collected as you would a plant specimen. Place in a plastic bag when 

collected. refrigerate until sent. 

35

(iii) Butterflies and moths : Kill the specimens by freezing, wrap lightly in tissue paper, 

and place in a crush-proof box. Careful handling is required because the pattern of 

scale coloration is often used in identification. 

(iv) Caterpillars : Send in alive on some of the host plant tissues in a plastic bag. 

Refrigerate until sent. 

(v) Grubs: Send in alive in a pint or two of soil enclosed in a plastic bag. Refrigerate 

until sent. 

(C) Packaging plant and insect samples 

It is important to package the samples properly to ensure they arrive in good condition 

at the plant clinic. Following are general guidelines for handling and packaging plant and 

insect samples. 

Use plastic bags 

For most samples including leaves, stems and roots, use plastic bags to prevent plant 

samples from drying out during transport. However, fleshy fruits, vegetables, or tubers in 

stages of decay should be wrapped individually in dry newspaper. 

Submit samples as soon as possible 

Decayed plant or insect samples are useless for an accurate disease diagnosis. Always 

plan to have samples arrive at the Centre within one or two days of their collection, if possible, 

or take steps to inhibit the deterioration or decay of samples (i.e., by refrigeration). 

Representative, moderate symptoms 

Do not submit dead plants for diagnosis. Place roots and soil together in a Plastic bag 

and close it securely. Place several branches showing decline or dieback in a separate 

plastic bag. For smaller plants, submit an entire plant (confine the root ball in a plastic bag 

tied tightly to the stem). Place the entire plant in another plastic bag and close it securely. 

Be sure there is no water on the foliage surfaces (this causes deterioration during shipping). 

General Packaging Guidelines 

1. Take your samples before applying pesticides; otherwise the ability to recover disease 

pathogens may be limited. 

2. Don’t add water or pack a sample that is wet or in wet paper 

3. After your samples are collected keep them refrigerated until submitted. 

4. Don’t mix samples in the same submission bag. Moisture from root samples will 

contribute to the decay of foliage if they are mixed together. 

5. Plant disease identification procedures do not utilize soil. Excess soil can be hand 

shaken from root systems. 

6. Please mark sample packages with a “Warning” if there are thorns or spines 

7. All samples must be accompanied with a completed “Plant Disease Diagnostic Form.” 

8. Note recent pesticide history on the form accompanying the sample 

9. Samples arriving from sites that are two days or less mailing time from a clinic can be 

sealed in plastic bags for shipping 

36

10. Samples arriving from distances greater than two days mailing time from a clinic should 

be packed tightly in a box with dry paper. 

11. Mail samples early in the week to avoid the weekend layover in the post office. 

12. For emergency samples or anything you suspect might be a dangerous exotic, use 

overnight courier services or overnight mail. 

Plant and Insect Sample Submissions 

Try to collect several specimens in different stages of development. Some identification 

keys we use are for adults, while other are for immature bugs. 

Insects submitted whole are more useful than when submitted in segments. 

Packing Insects 

Insects should be killed before shipping. Live caterpillars often pupate during shipment 

and beetles may eat their way out of the shipping container. 

Send all mature and immature insects (except butterflies and moths) in a glass vial or 

bottle containing ethyl or isopropyl (rubbing) alcohol. 

The vial or bottle must be properly padded in a mailing tube or other container to prevent 

breaking. Make sure that the cap for the vial is well secured so the alcohol doesn’t leak 

from within the vial during hipping. 

Send butterflies or moths dry in pill boxes or a similar container with tissue paper to 

prevent the specimen from being broken. 

It is often easier to identify an insect by seeing the damage it is doing to foliage, twig, 

fruit or other plant parts. 

If foliage or tender twigs are sent, they should be placed in a plastic bag and sealed. 

During the summer months, add a paper towel with the plant material when mailing 

specimens in a plastic bag. It absorbs excess moisture and helps prevent the plants 

from decaying and molds forming en route. 

Thus, plant material will remain moist and will arrive in a condition that enables analysis. 

Mailing leaves in paper envelopes results in their drying out so that insect damage is difficult 

to determine. 

Setting up plant health clinic (or diagnostic laboratory) 

The plant clinic acts as the farmer interface; the place where the farmer’s individual 

questions are answered and needs are met. It provides expert support, capacity building, 

training and diagnostics. The team works alongside local partners to train local people to 

become ‘plant doctors’. Then share the knowledge in surveillance and diagnostic techniques, 

integrated pest management, technology development, pesticide use and reduction, markets 

and government policy. 

How the plant clinics works? 

The clinics are made accessible to farmers by holding them on a regular basis in a 

prominent local meeting place, such as a market. When the farmer has a problem with a 

crop, he/she can bring a sample along to the plant clinic. At the clinic a trained ’plant 

doctor’ listens to the farmer, examines the sample, diagnoses the problem and offers a 

37

suggested treatment. Treatment suggestions are affordable for farmers and use locally 

available resources. The correct chemicals are recommended only when necessary.With 

access to these services farmers can tackle pests and diseases and produce healthy 

crops and productive yields. With successful harvests farmers can feed and support 

their families. Diagnosis is not always straightforward. Sometimes plant doctors need to 

send samples to a laboratory (in exactly the same way that a family doctor sends samples 

to a hospital laboratory). 

Table 1. Plant health clinics around the world. 

Country No. Started Managed by 

Bangladesh 25 2004 RDA Bogra, AAS, and Shushilan 

Bolivia 7 early 2004 CIAT Santa Cruz, PROINPA, and UMSS 

DR Congo 8 March, 2006 Université Catholique du Graben, Butembo 

India 2 August, 2006 GB Pant University of Agriculture and Technol. 

Indonesia 2 October, 2007 University of North Sumatera (USU) 

Nicaragua 14 March, 2005 Farmer organisations, NGOs, INTA, and others. 

Supported by PASA II (danida) and other donors. 

Uganda 4 July, 2006 Socadido, SG2000, Caritas and MAAIF 

Vietnam 2 June, 2007 SOFRI 

With India planning to introduce clinics in all 40 states, the stage is set for providing 

poor farmers with better advice that helps them grow healthy crops with reduced risk and 

lower costs. 


Borror, Donald J., Dwight M. DeLong and Charles A. Triplehorn.1964. An Introduction to the 

study of insects, p. 730-747. Holt, Rinehart and Winston, New York. 

David Cook. 2005. Photographing Insects and Spiders & what we need to see for identification. 

Entomology & Plant Pathology, University of Tennessee, p1-25. 

Knutson, Lloyd. 1964. Preparation of specimens submitted for Identification to the Systematic 

Entomology Laboratory, USDA. Bull. ent. Soc. Am. 22 : 130. 

Methven,K.M., Jeffords,R., Weinzierl, R.A. and McGiffen.1995. How to Collect and Preserve 

insects. Illinois Natural history Survey, Champaign-Urbana, pp.76. 

Sabrosky,CurtisW. 1971. Packing and shipping of pinned insects. Bull. ent. Soc. Am. 17 : 

6-8. 

William H. Hoffard. 2001. How to Collect and Prepare Forest Insects, Disease Organismsa 

and Plant Specimens for Identification. USDA Forest Service, Southeastern Area, State 

and Private Forestry 1720 Peachtree Road, N.W.Atlanta. 

38

INSECT SAMPLING FOR DECISION MAKING 

IN CROP LOSS ASSESSMENT 

R. K. Saini 



Different activities of insects such as their populations on the crop, damage inflicted to 

the plants, insect stage present, local movement, migration and dispersal etc. are documented 

through surveillance. The decision, whether the control interventions are needed depends 

upon the accurate estimation of numbers. Further, based on the study of interrelations of 

pests populations with various environmental factors we should be able predict the future 

population trends or outbreaks of pests so that appropriate control measures are initiated 

when required. So, survey is a planned activity to collect some data. When survey of the 

same place or locality is carried out at regular interval to record some observation or to 

ascertain the changes or fluctuations in the subject of study it is called surveillance. 

2. Objective of pest monitoring 

In relation to pest management, the major objective of pest monitoring is to assess the 

pests’ population and/or the damage caused by them to the crop regularly in order to decide 

when to undertake control interventions. The data so obtained for several years in the 

background of varied environmental conditions may help in working out pest-environment 

relationships or interactions to aid in pest forecasting with reasonable precision. Further, 

endemic areas of various pests may also be marked. Since pest surveillance is a costly 

affair it would be quite appropriate to gather information on other parameters also, which 

affect the success of a pest management programme. For example, surveillance programme 

may be planned in such a way that could include information on natural enemies of pests 

also. Similarly, surveillance could also be undertaken for monitoring of build up of insecticide 

resistance in insects. To achieve the above objectives one should have a thorough knowledge 

of the diagnostic symptoms of damages caused by the pests on the crops and also of pests’ 

life history and behaviour. 

Sampling insect populations 

It is not possible or even desirable to count all the insects in a habitat. Therefore, to 

estimate the population density or the damage caused by it to the crop, one has to resort to 

sampling. The basic principle of pest sampling and advances made in sampling have been 

reviewed by Morris (1960), Cochran (1977), Southwood (1978) and Kuno (1991) and Binns 

and Nyrop (1992). However, randomization and choice of sample unit are the fundamentals 

of sampling. Importance of drawing a random and representative sample is well known. The 

total number of samples to be taken depends on the degree of precision required. This may 

be expressed either in terms of achieving a standard error of pre-determined size or in 

probability terms. 

Assessment methods (Chiarappa, 1971) 

A detailed account of assessment methods has been given by P. T. Walker in Chiarappa, 

L. ed. (1971). The following information is mainly based on the methodology suggested 

therein. There are almost as many ways to assess pests as there are types of pest. A good 

guide to all aspects is Southwood (1978). For general accounts, see Bardner and Fletcher 

(1974); chapters in Chiarappa (1971). Survey manuals have been produced by USDA (1969) 

39

and the Philippines, Thailand, India, and other countries. Standard pest evaluation methods 

have been published by IRRI for germplasm selection in rice and other crops (Standard 

evaluation system for rice) and by other international agricultural institutes for other crops. 

Agrochemical companies sometimes produce guides to pest assessment in connection 

with pesticide trials (Puntener 1981). 

Choosing assessment methods 

When choosing or developing methods, consider the following aspects (Walker 1980): 

they should be quick, simple, and inexpensive, and should measure the actual pest population 

or damage as accurately as possible. Methods should be standardized, to make possible 

comparison of different assessments, to remove bias due to the observer, and to allow study 

and testing of the value of the method. Standard methods should be published in a survey 

manual, with details of how, where, and when to sample; the size and number of samples; 

and the stage of pest and crop, with keys and growth stage charts (Reissig et al. 1986). 

When assessing intensity or severity of damage, standard area keys, such as those used 

for disease lesions, are valuable to avoid observer error. 

DIRECT ASSESSMENT METHODS 

On the ground 

Insects and other animals should, if possible, be counted on a standard base, usually 

area of ground (e.g. number of larvae per m 2 ). If counted on a nonstandard unit, such as 

length of crop row, weight of crop, hill, plant, shoot, tiller, stem, internode, leaf, head, grain, 

or panicle, the unit should be converted to a m 2 base. 

Direct counts. Aphids are counted per unit of leaf or tiller, bugs per panicle, 

leafhoppers per stem, beetle larvae per volume of soil, etc. Absolute pest density is found by 

multiplying by the number of units per m 2 . 

Cutting open. Grains are cut open to count fly or beetle larvae, legume pods to count pod 

borers, stems for stem borers, roots for root borers, etc. 

For example, formulae for per cent rice tiller infestation by stem borers from samples in 

infested hills (Gomez and Gomez, 1964) : 

% infested tillers = 

No. of infested tillers in Hi 

X 

Number of Hi x 100 

Total tillers in Hi Total hills 

Where Hi = Number of infested hills 

Beating, brushing, and knockdown. Plants or panicles may be shaken into a box or 

on a sheet, hoppers or bugs collected with an electric pump (Cariño et al. 1979) or by mouth 

suction inside a walled quadrat. A non-persistent knockdown agent such asCO 2 (Aquino and 

Heinrichs 1986) or insecticide such as dichlorvos or a pyrethroid may be used on a plant or 

panicle in a bag, box, or on a sheet to collect fallen insects. Pests such as aphids or mites 

can be brushed off leaves, sometimes with a mechanical brush, and sometimes collected in 

a preservative liquid. 

Washing off. Aphids, mites, or eggs removed with a solvent can be washed off and 

measured by volume. 

Crushing. Colored aphids or mites can be crushed on glossy or absorbent paper, or 

grains containing live insects crushed on ninhydrin paper, and the spots produced counted. 

40

Pests in soil and debris 

Samples of a standard area to a known depth and specified volume are taken with a core 

borer or by digging. A preliminary survey will ensure that samples are representative of pest 

distribution. In dry extraction (K. E. Fletcher in Chiarappa, 1971), such as the Tullgren 

funnel, a light bulb or other source of heat drives out insects which are collected in an 

alcohol tube. In wet extraction (J. F. Newman in Chiarappa, 197l), as in the Salt and Hollick 

method, samples may be soaked, shaken with detergent, insects floated off in salt solutions 

such as magnesium sulfate, and separated by centrifuging. Some soil insects can be driven 

out of the soil with an insecticide or an irritant such as formaldehyde. 

In the air 

Counts in the environment are more difficult to standardize. It may be possible to relate 

catches by suction trap, sweep net, light trap, or pheromone trap to actual pest population 

densities on the ground by correcting for differences in the trap or differences in surroundings 

(brightness, position, temperature, wind speed, etc.), but such counts are usually no more 

than estimates of actual pest populations. As with all samples, they are liable to sampling 

error. These methods, however, are so valuable the limitations are often accepted. Some 

methods for locusts are given by Symmons (1981). 

Sticky traps : Aphids, mites, hoppers, flies, hymenoptera, caterpillars, and beetles may 

be caught by this method. A flat, cylindrical, or round board or plastic sheet is coated with 

sticky material, such as tree-banding grease (Ryan and Molyneux 1981) or car grease, and 

placed on the ground or in an attractant trap within the standing crop. The catch is washed 

off in solvent, identified, and counted. Height and position of the trap in the crop are important, 

and regular attention is necessary to protect it from rain or dust. Southwood (1978) compares 

catches by different hinds of trap. 

Color traps : Leaf pests are often attracted to BS 0.001 or Munsell 5 OY 9/14 Yellow, 

other pests like white, some fruit pests like red coloured traps. The best size, shape, and 

color of trap to use is determined through trial. Color is sometimes combined with water 

traps, as Kisimoto (1968) did for Laodelphax in rice, or with sticky or pheromone traps. 

Water traps : Aphids, hoppers, and flies are commonly caught. Shallow plastic dishes, 

5-8 cm deep, containing water, detergent, and an oil film are placed in or near the crop. Trap 

height and wind direction are important. A colored dish may add attraction. Overflow holes 

are useful to prevent flooding. 

Chemical attraction : Attraction to a trap is a piece of the food plant, a chemical from 

the plant, or other substance. Fruit flies, sorghum shootflies, banana weevils, coconut beetles, 

and moths and hymenoptera can be trapped this way. A trap crop may also be used, 

particularly if destructive sampling is planned. 

Pheromone traps : Trapping by attracting males to female pheromone or, if the 

pheromone is not available, to the female (or in some cases, females to male), has a great 

advantage in that it is specific and traps are simple, relatively inexpensive, easy to maintain, 

and less liable to theft or vandalism. These traps can indicate when a pest attack is near 

and, sometimes, how large an infestation to expect (Campion and Nesbitt 1981). The 

development and supply of pheromone are best left to experts. Trap design is important 

(Lewis and Macauley 1976, Steck and Bailey 1978). Flat, cylindrical, and triangular shapes; 

and cartons, funnels, and plastic bags with talc, sticky surfaces, and water baths have been 

used, depending on the size and behavior of the insect and the weather. The position of the 

trap in the crop and the condition and rate of release of pheromone are important. The 

41

difficulty is to relate the number caught, particularly if the insects caught are only males, to 

the actual pest life cycle, level of pest attack, the best time to apply a control, and crop 

yield loss. 

Sweep net : Sweeping can give repeatable results if the diameter of the net opening 

and the number, extent, and frequency of sweeps are constant. The method was analyzed 

by Ruesink and Haynes (1973). 

Suction traps : Trapping or collecting insects by air suction is useful where attraction 

to light or chemicals is of no use and where motor, mains, or battery electric power is 

available. Continuous sampling at different levels above the crop can give valuable indications 

of when, which and how many pests will attack 

Light traps : If an oil, gas pressure, or electric light source is available, a light trap is 

valuable for monitoring relative and absolute pest numbers and the seasonal appearance of 

many species of moths, hoppers, and beetles (Rabb and Kennedy 1979, Bouden 1982).The 

strength, wavelength, and direction of the light, the weather, and the presence of other light, 

including moonlight (Verheijen 1960), are important. Some traps use ultraviolet or black 

light, have a timing mechanism, or are daylight activated, and are equipped with a protective 

roof, electrified vanes, or a suction pump. 

Insecticide (e.g. dichlorvos) and something to prevent damage to the insects should be 

placed in the trap container. A serious disadvantage is that the large, nonspecific catches 

often demand some sort of sample divider (Shepard 1984). 

Pitfall traps : In dry areas, smooth-sided plastic pots level with the soil surface will 

collect mobile ground insects, predators, etc. They need frequent attention and protection 

from flooding, birds, and ants. 

Shelter traps and emergence traps : Some animals may be trapped and counted by 

collecting them under some form of shelter (for example, termites under sheets of paper 

[McMahen and Watson 1977]). Insects emerging from the soil can be caught using an inverted 

funnel with a collecting tube at the top. 

Mark, release, and recapture : If marking does not alter behavior, insects or other 

animals can be marked, released, and recaptured. Populations can be estimated using the 

Lincoln Index : 

Number marked and released x total number caught 

Population = 

Number marked caught 

The method used depends on whether pests are removed or replaced, and on survival 

and migration (Blower et al 1981). Marking can be with combinations of paint spots, external 

coloring or UV fluorescent dust, internal dye, or radioactive, bacterial, or genetic markers. 

INDIRECT ASSESSMENT METHODS 

It is often easier, quicker, and cheaper to count or estimate the indirect effects of pests. 

The difference between incidence (damage or number of damaged plants) and intensity or 

severity (degree or extent of damage) should be noted. Incidence is a discrete measure, 

intensity is continuous and finite. 

Whole plants. The number or percentage of missing or damaged plants is often recorded. 

Soil pests, cutworms, stem borers, etc., may cause loss of plant stand. Errors in damage 

assessment may occur if the number of missing plants is not taken into account. 

42

Stems : The number or percentage of wilted sterns or dead central shoots (deadhearts) 

indicates the intensity of attack by stem borers, shoot flies, or boring beetles; the number of 

silvershoots (galls) indicates intensity of attack by gall midge. Number of exit holes or the 

presence or length of tunnels have also been used. The usefulness of number of nodes 

bored depends on the pest species and the variety and stage of crop. Termite, ant, cutworm, 

sawfly, and rodent attack can be assessed from fallen or cut stems, cassava mite and 

mealybug attack by number of stunted, leafless shoots. 

Leaves : Holes, spots, mines, rolls, or epidermis removal indicate attack by stem borers, 

leaf caterpillars, semiloopers, caseworms, leaf miners, leaf beetles and their larvae, termites, 

or orthoptera. Damage can be counted or its area measured by counting the dots of a dot 

matrix grid seen through the holes, by weighing paper of the same area, by photographic 

methods and photometry, or, more expensively, by laboratory or portable electronic scanning 

and area integration devices, such as the Lincor. With these, the degree of contrast to be 

measured can be selected. The area of undamaged leaf can be obtained from a “length x 

breadth x a constant” formula. 

Seeds, grain, and fruit : Damaged seed, seed heads, and cobs; exit holes; and unfilled 

grain panicles, or white heads in rice are counted. In larger fruit, the area of damage can be 

measured. Damage to coffee, cacao, cotton, fruit, coconut, etc. is often assessed this way. 

Roots : Root length and volume or dry weight of damaged and undamaged fibrous roots 

are used to assess pest attack. Whole roots, samples, or even sections of the root mass, if 

a correction factor has been calculated, can be used. Damage to tuberous roots is measured 

by counting lesions or areas of damage on the surface or from a cut section. 

Amount of by-product : The presence or amount of insect product, such as borer excreta 

or aphid or planthopper honeydew, may be used to quantify pest attack. 

Time to sample and method to use 

The best time to sample pests or crop damage usually is when pests will have the 

maximum effect on the economic crop yield. This may be at a critical event in pest 

development, such as first egg appearance or adult emergence. or at a critical growth stage 

of the crop, such as at germination or early tillering. 

Scores or rating scales 

For quicker and easier assessment, or because of the difficulty of counting great numbers 

or complicated areas of damage, both pests and their damage are often grouped into grades, 

or scales (Standard evaluation system for rice, IRRI 1980) or given scores or ratings. Scales 

may be arithmetic (grades 1, 2, and 3 being 0- 10, 11- 20, 21 -30, etc.) or geometric 

(logarithmic: 0 (really 1)- 10, 11 - 100, 101-1,000, etc.). Grades and scores can be added, 

averaged, and analyzed, but they are discontinuous and finite and may not be normally 

distributed, needing transformation before analysis. 

Pest or damage frequency distribution 

The frequency distribution of pests or damage (the number of samples of different sizes) 

should be known before a sampling plan is designed or data analyzed. A preliminary survey 

will show whether pests or damage are distributed in a regular pattern, at random, or in 

clumps. The number of zero counts and the average number of pests per sample are important. 

If the frequency distribution is nonnormal, parametric statistics, and hence standard errors, 

confidence limits, analyses of variance, and regressions will not be valid. 

43

Number and size of samples 

Factors such as ease of sampling, accessibility, and time and money available for 

sampling should be considered. There are formulae for calculating sample size from the 

variance, cost, etc. The purpose of the sample is important. Is it descriptive and qualitative, 

or quantitative but only preliminary? Is it to give relative results or an exact economic 

assessment on a valuable crop? 

Type of sampling : Different types of sampling include randum, satisfied randum, vacuum 

sequential, etc. 

If the basic statistics of the pest or damage population are known, sequential sampling 

is useful in deciding whether or not to control. Sample size depends on the population 

found. Upper and lower limits are specified and sampling continued until the number of 

pests found goes above or below those limits. The method is described by Onsager (1976). 

Sampling techniques for some important crop pests 

Some commonly used sampling techniques employed for some of the important crop 

pests are summarized in Table 1. However, these may be suitably modified keeping in view 

the objectives and degree of precision required. 

Table 1. Sampling techniques for major insect pests of some crops 

Crop Pest Economic threshold Method of sampling 

1 2 3 4 

Cotton Leaf hopper (jassid) 2 nymphs/leaf or yellowing Count leafhopper nymphs from underside 

(Amrasca biguttula biguttula) and curling of 20% leaves of three fully developed leaves in the 

from margins. upper canopy of each of 20 random plants 

or count leaves showing yellowing 

and curling from margins and healthy 

leaves of 20 random plants in a field. 

Whitefly (Bemisia tabaci) 6-8 adults/leaf Count whitefly adults as above. 

Spotted bollworm (Earias spp.) 10% drooping shoots or Count drooping shoots and healthy shoots 

5-10% infested fruiting of 25 random plants or examine all green 

bodies fruiting bodies of the above plants for spotted 

bollworm induced holes or damage. 

Pink bollworm 5-10% infested fruiting Count rosetted flowers and examine all 

(Pectinophora gossypiella) bodies fruiting bodies for damage by pink 

bollworm on 25 random plants. 

American bollworm 5-10% infested fruiting Examine all fruiting bodies of 20-25 random 

(Helicoverpa armigera) bodies or one larva/2 plants. plants for the pest damage and also count 

number of larvae present. 

Aphid (Aphis gossypii) 10-15% infested plants Examine presence of aphid or its symptoms 

on 20-25 random plants. 

Thrips (Thrips tabaci) 10 thrips/leaf or 25% Same as for aphid 

infested plants 

Paddy a) At earing stage 5-15 insects/hill Select 5 micro-plots of 1m 2 each in a field 

Green leafhopper (Nephotettix and shake vigorously plants in 5 hills/plot 

nigropictus & N. virescens)/ or shake vigorously 25 random plants 

white backed plant hopper and count leafhopper fallen on water. 

(Sogatella furcifera)/brown 

leafhopper (Nilaparvata lugens) 

44

) At flowering stage Same as above 

Stem borer 5-10% plants with dead- Count infested and healthy tillers in 25 

(Scirpophaga incertulas) hearts or 2% white ears or random plants. 

one egg mass or moth/m 2 . 

Leaf-folder 2 damaged leaves/ plant Count infested and healthy plants among 

(Cnaphalocrocis medinalis) or one larva/hill 25 random plants or count number of 

larvae in 25 plants. 

Root weevil 2 grubs/hill Same as above 

(Hydronomidius molitor) 

Rice gundhi bug 1-2 insects/hill Count the insect on 25 random plants. 

(Leptocorisa acuta) 

Sugar- Early shoot borer Dead hearts in 15-20% From 5 random rows in a field, examine 

cane (Chilo infuscatellus) tillers 100 tillers/row for dead-hearts. 

Top borer Dead hearts in 10% tillers Same as for early shoot borer 

(Scirpophaga excerptalis) or 5% dead hearts in the 

ratoon crop 

Gurdaspur borer Drying of 10% canes Count dried-up and healthy canes as above. 

(Acigona steniella) 

Pyrilla (Pyrilla perpusilla) 3-5 insects/leaf Count pyrilla nymphs and adults on 10 

random plants taking 6 (2 upper, 2 middle 

and 2 lower) leaves/plant. 

Black bug (Cavelerius sweetii) 25 insects/plant Count nymphs and adults on 20-25 

random plants. 

Sorghum Shoot fly (Atherigona soccata) 

a) After one week of crop One egg/plant or presence Examine 30 plants for the presence 

germination of eggs on 5% plants of eggs. 

b) After two weeks of Dead-hearts in 15% plants Examine 30 plants for the presence of 

germination eggs or count dead hearts. 

Stem borer (Chilo partellus) Symptoms of damage (i.e. Examine 30 plants for damage 

dead hearts, shot holes in symptoms. 

leaves, unfilled ear head etc.) 

Sorghum midge One midge/ear head at Count gall midge adults on 50 random 

(Contarinia sorghicola) 50% flowering plants in the morning. 

Aphid (Rhopalosiphum maidis) 10-20% infested plants or Examine 100 random plants in a field. 

14 aphids/central shoot 

Painted bug (Bagrada hilaris) One insect/meter Count painted bug in one meter row 

row length length from 20 random sites in a field. 

Gram Gram pod borer One larva/meter Count larvae in one meter row length from 

(Helicoverpa armigera) row length 10-20 random sites in a field. 

Okra Leafhopper 2-5 nymphs/leaf Same as in the case of cotton. 

(Amrasca biguttula biguttula) 

Tomato Fruit borer One larva/m 2 Count larvae in 1m 2 micro plot from 10 

(Helicoverpa armigera) random sites in a field. 

45


Atwal, A.S. and Singh, B. 1990. Pest Population and Assessment of Crop Losses. Indian 

Council of Agricultural Research (ICAR), New Delhi. 

Binns, M.R. and Nyrop, J.P. 1992. Sampling insect populations for the purpose of IPM 

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Cammell, M.E. and Way, M.J. 1987. Forecasting and monitoring. In: Burn, A.J., Coaker, 

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Brace Jovanovich Publishers, London, pp. 1-26. 

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and Commonwealth Agricultural Bureaux International, Slough, UK. 123 p. 

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monitoring and pest management. Environ. Ent. 11 (6) : 1127-1133. 

Kuno, E. 1991. Sampling and analysis of insect population. Ann. Rev. Ent. 36 : 285-304. 

Luttrell, R.G., Fitt, G.P., Ramalho, F.S. and Sugonyaev, E.S. 1994. Cotton pest management: 

Part-I. A worldwide perspective. Ann. Rev. Ent. 39 : 517-526. 

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Saddle River, New Jersey 07458, pp. 211-254. 

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in Agriculture. Boca Raton, USA, CRC Press Inc. 

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Entomology: Novel Approaches, 2007, Eds. P.C. Jain and M.C. Bhargava, New India 

Publishing Agency, New Delhi. 

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Thankappan, M. 2001. Access to satellite data for time-critical applications STAR and 

SPOTLITE. First Australian Geospatial Information and Agriculture Conference, Sydney, 

Australia, July 17-19, 2001. pp. 497-506. 

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remote sensing techniques in insect ecology. Entomological Knowledge 40 (2) : 97-100. 

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42 (3) : 315-326. 

46

DIAGNOSTIC SYMPTOMS AND ASSESSMENT 

OF LOSSES DUE TO ARTHROPOD PESTS 

IN KHARIF VEGETABLES 

S. S. Sharma 


CCS.Haryana Agricultural University, Hisar 

Arthropod pests are the major constraints to agricultural production. A large number of 

insect and mite pests attack vegetable crops during all stages of growth- seedling to storage. 

Of these only about two dozen have economic importance across agro- ecological zones. 

Some more important species include leafhopper (Amrasca bigu tula bigu tula), shoot and 

fruit borer (Earias vittella) and red spider mite (Tetranychus urticae) in okra; shoot and fruit 

borer (Leucinodes orbonalis), lace bug (Urentius hysterricellus), whitefly (Bemisia tabaci), 

leaf webber (Eublemma olivacea) and hadda beetles (Epilachna spp) in brinjal; fruit fly 

(Bactrocera cucurbitae) and red pumpkin beetle (Raphidopalpa foveicollis) in cucurbitaceous 

crops; termite (Odontotermes obesus), thrips (Thrips tabaci), whitefly (Bemisia tabaci) and 

yellow mite (Polyphagotarsonemus latus) in capsicum. 

INSECT-PESTS OF OKRA 

Leafhopper : Amrasca biguttula biguttula (Ishida) 

F : Cicadellidae O : Hemiptera SO : Homoptera 

Nature of damage : Both nymphs and adults suck cell sap usually from lower surface 

of the leaves and inject toxic saliva. Infested leaves turn yellow and curl upwards and become 

cup shape. In case of severe infestation, the leaves become brick red, brittle and finally drop 

down. This pest is active throughout the year except in severe winter when only adults are 

seen. 

Economic Threshold (ET) : 4.66 leafhoppers per plant (Faleiro and Rai, 1988), 3 nymphs 

per leaf/plant (Bolano, 1997), 2 nymphs per leaf (Agarwal et al., 2000). 

Loss : Depending upon the crop season yield losses due to this pest can range from 

63.4 to 88.1 per cent in Haryana (Sharma et al., 2001) and 54 -66 per cent in Karnataka 

(Krishnaiah, 1980). 

Mealybug (Phenacoccus solenopsis Tinsley) F : Psudococcidae O : Hemiptera 

Nature of damage : Both nymphs and adults suck the cell sap from the lower side of 

the leaves or from the shoots. The infested plants remain stunted and finally dry away. 

Under severe infestation there is a heavy loss to the crop. The male adults are not harmful to 

the crop. 

Blister beetle (Mylabris pustulata) in okra F : Meloidae O : Coleoptera 

Nature of damage : The adult beetles are the only feeding stage .The beetles feed on 

flower petals, anthers and fruit by scratching the surface. 

Shoot and fruit borer : Earias vittella (Fabricius) F : Noctuidae O : Lepidoptera 

Nature of damage : In the early stage of the crop larvae bore into tender shoots and 

tunnel downward. The growing tip is killed; shoots droop down and side shoots emerge. 

Later on when fruiting bodies appear caterpillars bore in the flower buds and fruits. The 

damaged buds drop down and the fruits get curved from the point of injury. The larva enters 

the fruit and feeds on the developing seeds. The damaged fruits become unfit for consumption. 

47

Economic Threshold (E.T.) : 5.3 % infestation of fruits (Dhandapani, 1985) or infested 

plant per meter row. 

Loss : There is a heavy loss in seed production. Yield loss reported by different workers 

is 28.3 per cent in Haryana (Sharma et al., 1993), 38.43 per cent in UP (Satpathy and Rai, 

1998), 22.79 - 50.52 per cent in Punjab (Brar et al., 1994), and 54.04 per cent in Rajasthan 

(Chowdhury and Dadheech, 1989). 

Fruit borer : Helicoverpa armigera 

Nature of damage : The larvae feed on flowers and pods by making holes in them. 

Loss : About 22 per cent fruit damage in Himachal Pradesh has been recorded by Raj et 

al. (1993). 

Red spider mite : Tetranychus urticae (Linnaeus) F : Tetranichidae O : Acarina 

Nature of damage : Larvae, nymphs and adults suck cell sap. Large-scale webbing is 

done on the leaves, which creates hindrance in normal growth. Minute white spots appear 

on the leaves due to feeding by this pest, which is active from March to October. 

Loss : 19.5 to 24.7 per cent losses in yield of green okra fruits. 

INSECT PESTS OF BRINJAL 

Shoot and fruit borer: Leucinodes orbonalis Guenee F : Pyralidae O : Lepidoptera 

Nature of damage : Newly hatched caterpillars bore into petioles, midribs, tender shoots 

and fruits. Damaged twigs dry and the growing point of shoots droop down. Later on, the 

larvae attack flower buds and fruits. Such fruits show exist holes. 

Loss : Loss reported by different workers is 63 Haryana (Dhankhar el al., 1977), 50 per cent in 

Tamil Nadu (Srinivasan and Gowder, 1969), 48 per cent in Maharashtra (Mote, 1981), 11.1-47.18 in 

(Punjab Gill and Chadha, 1979), 54 -66 per cent Karnataka (Krishnaiah, 1980), 25.82 - 92.50 per cent 

in Rajasthan (Kumar and Shukla, 2002) and 20.54 per cent in UP (Mall el al., 1992). 

Hadda beetle : Henosepilachlna vigintioctopunctata (Fabricius), 

Epilachna dodecastigma F : Coccinelidae O : Coleoptera 

Nature of damage : Both grubs and adults cause damage by feeding on chlorophyll of 

leaf tissues, leaving parallel bands of uneaten tissues in between. Its peak activity is from 

April to May and September to October. 

Brinjal lacewing bug (Urentius hysterricellus) F : 

Nature of damage : Both nymphs are adults suck the sap from the leaves causing 

yellowish spots which together with the black scale-like excreta deposited by them. The 

nymphs feed gregariously on the lower surface of the leaf and adults are found feeding and 

moving individually on lower and upper side of the leaf. 

Brinjal stem borer : Euzophera perticella Ragonot F : Phycitidae O : Lepidoptera 

Nature of damage : The young larvae feed for a few minutes on exposed parts of plants 

before boring into the stem where it feeds on the pith by making longitudinal tunnels. Damaged 

plants wither and dry away. Peak period of activity is May-June. 

INSECT PESTS AND MITE OF CUCURBITACEOUS CROPS 

Melon fruit fly : Bactrocera cucurbitae F : Tephritidae O : Diptera 

Nature of damage : Newly hatched maggots feed on the fruit pulp. Attacked fruits can 

be identified by the presence of brown juice oozing out of the puncture made by females for 

egg laying. Such fruits become distorted, rot and fall prematurely. 

Loss : In bitter gourd a loss of 60- 80 per cent in HP (Gupta et al., 1992); in Cucumber, 

60- 80 per cent in Assam (Borah, 1996), 83% in HP (Gupta et al., 1992); in Little gourd 63% 

48

DIAGNOSTIC SYMPTOMS OF INSECT-PESTS' DAMAGE IN VEGETABLES 

Diamond-back moth 

Leafhopper in okra 

Brinjal aphid 

Aphid on radish Onion thrips 

Red mite in okra 

Tomato fruit borer 

Red pumpkin beetle 

Cabbage butterfly 

Brinjal shoot & fruit borer 

Hadda beetle 

Fruit fly in bittergourd 

Blue butter fky in pea

in Gujarat (Patel, 1994), Muskmelon 76 -100% in Rajasthan (Pareek and Kavadia, 1994). In 

snake gourd 63 per cent in Assam (Borah and Dutta, 1997) and in Sponge gourd 50 per cent 

in AP (Gupta et al., 1992) has been reported. 

Red pumpkin beetle : Rhaphidopalpa joveicollis (Lucas) 

F : Chrysomelidae O : Coleoptera 

Nature of damage : Young grubs feed on roots and underground portion of host plants 

and fruits touching the soil. Adult beetles feed voraciously on leaf lamina in a circular fashion 

preferring young seedlings. Main period of activity of this pest is from March--October (highest 

peak in April-June). 

Leaf miner F : Chrysomelidae O : Diptera 

Nature of damage : The maggots make mine inside the leaf tissues. The zigzag 

serpentine white lines are visible from the upper surface of the leaf. The photosynthesis is 

hampered due to these lines. 

Chlli 

Yellow mite (Polyphagotarsonemus latus) O : Acarina 

It is commonly known as the yellow mite and is a polyphagous pest. It is a minute, very 

active and can only be seen with magnifying lens moving very fast on lower and upper 

surface of tender leaves. Both nymphs and adults scrap the terminal leaves and auxiliary 

leaves and suck cell sap. The damaged leaves become narrow with twisted and elongated 

petiole. Overall size of the leaf increase in size and downwards boat shaped curling of 

damaged leaves takes place. 

Economic Threshold (ET) : One mite per leaf (Ukey et al., 1999) 

Loss : As high as 34.14 per cent in AP (Ahmad el al., 1987) 

Thrips(Scirtolhrips dorsalis) F : Thripidae O : Thysanoptera 

Nature of damage : Both nymphs and adults lacerate the leaf tissues and suck the sap 

oozing out of it. White spots are formed on the leaves due to their feeding. 

ET: 2 thrips per leaf (Nelson and Natarajan, 1994) 

Loss : Crop loss of 11.8 per cent Assam (Borah and Langthasa, 1995), 50 per cent in 

Tamil Nadu (Nelson and Natarajan, 1994), >90 per cent (chilli pepper) in Karnataka (Kumar 

et al. 1995), 11 -32 per cent (sweet pepper) in Karnataka (Kumar et al. 1995). 

EXTENT OF LOSSES IN VEGETABLE CROPS : The pest status or population varies 

from place to place in different agro climatic conditions. The biotic factors and abiotic factors 

influence the pests and the extent of damage caused by them. 

METHODS OF ESTIMATING CROP LOSSES DUE TO INSECT PESTS IN VEGETABLE CROPS 

1. Mechanical Protection : Crop is raised under net, wire gauge or cotton cloth depending 

upon the crop. The yield under such enclosures is compared with that of infested crop 

under similar conditions. The mechanical protection may change the microclimate of the 

crop and affect the yield which is the main drawback of this method. 

2. Chemical Protection : Crop is protected by chemical insecticides. Yield of the treated 

plants is compared with infestated plants having the same soil and fertility status. This 

is the most popular technique. 

3. Comparison of Yield in Different Fields Having Different Degrees of Pest Incidence : 

Yield is recorded per unit area in different fields carrying different degrees of pest 

infestation. The correlation between the crop yield and degree of infestation is used to 

estimate the damage. 

49

4. Comparison of Average Yield of Individual Plants : The pest incidence and the yield 

of individual plant is recorded and loss in yield is calculated by comparing the average 

yield of healthy plants and various degree of infested plants. 

5. Average Damage Caused by Individual Insects : This method is easy for leaf feeding 

insects. The amount of damage caused by different stages or age of the insect pest and 

the exact nature and amount of loss caused by them can be estimated. 

6. Simulated Damage : Zhu et al. (1994) assessed the yield loss in cabbage caused by 

lepidopterous complex consisting of Pieris rapae, Plutella xylostella, Spodoptera litura, 

and Spodoptera exigua through simulated damage done by punch holes on cabbage 

leaves with more than 90% accuracy. 


Agarwal, N., Bhanot, J. P. and Sharma, S. S. 2000. Determination of economic threshold of 

leafhopper, Amrasca biguttula biguttula (Ishida) on okra. JNKVV. Res.J. 34 (1 & 2) : 38-41. 

Borah, S. R. and Dulta, S. K. 1997. Infestation of fruit fly in some cucurbitaceous vegetables. 

J. agric. Sci. North East India 10 : 128-131. 

Brar, K. S., Arora, S. K. and Gllai, T. R. 1994. Losses in fruit yield of okra due to Earias spp. 

as influenced by dates of sowing and varieties. Journal of lnsect Science 7 : 133-135. 

Faleiro, J. R. and Rai, S. 1988. Yield infestation relationship and economic injury level for 

okra leafhopper management in India. Tropical Pest Management 34 : 27-30. 

Kalra, V. K., Sharma, S. S. and Tehlan, S. K. 2006. Population dynamics of Hyadaphis 

corianderi on different cultivars and varieties of coriander and seed yield losses caused 

by it. Journal of Medicinal and Aromatic Plant Sciences 28 : 377-378. 

Krishnaiah, K. 1980. Assessment of Crop Losses due to Pests and Diseases (Ed. H.C. 

Govindu). UAS Tech. Series. No. 33 : 259-267. 

Kumar, N.K.K. 1995. Yield loss in chilli and sweet pepper due to Scirtothrips dorsalis Hood 

(Thysanoptera: Thripidae). Pest Managemenl in Horlicuitural Ecosystems. 1 : 61-69. 

Mall, N. P., Pandey, R. S., Singh, S. V. and Singh, S. K. 1992. Seasonal incidence of 

insect-pests and estimation leaf losses caused by shoot and fruit borer on brinjal. Indian 

Journal of Entomology 54 : 241-247. 

Parsad , R. and Singh J. (2007).Estimation of yield loss in okra caused by the red spider 

mite (Tetranychus urticae Koch) under the influence of two different dates of sowing. 

Indian J. Ent. 69 (2) : 127-132. 

Saha, N. N. 1982. Estimation of losses in yield of fruits and seeds of okra caused by the 

spotted bollworms, Earias. spp. unpubl. Ph.D. thesis. Punjab Agril. Univ., Ludhiana. 

Sharma, S. S., Kalra, V. K. and Kaushik H. D. 2001. Assessment of yield losses caused by 

leafhopper, Amrasca biguttula biguttula Ishida on different varieties/cultivar of okra. 

Haryana J. hort. Sci. 30 (1 & 2) : 128-13. 

Shivalingaswamy, T. M, Satpathy, S. and Banerjee, M. K. 2002. Estimation of crop losses 

due to insect pests in vegetables. In Resources management in plant protection Vol. 1 

Ed .by B.Sarath Babu, K.S.Varaprasad, K. Anitha, R.D.V.J.Prasada Rao,S.K.Chakrabarty 

and P.S.Chandurkar Pblished by Plant Protection Association of India, NPPTI Campus, 

Rajendranagar, Hyderabad (AP). pp. 27-31. 

50

DIAGNOSITIC SYMPTOMS AND ASSESSMENT 

OF LOSSES DUE TO INSECT-PESTS 

IN WINTER VEGETABLES 

P. C. Sharma 

Department of Entomology, College of Agriculture 

CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur-176 062 

The vegetables form an essential component of the human diet especially in case of 

India and some South Asian countries. India ranks second in the production of vegetables 

after China and occupy 5.993 million hectares area and the total annual production is around 

90.83 metric tonnes (Gopalakrishnan, 2007). There is a need of around 5-6 million tones of 

food to feed 1.3 billion India’ population by 2020 AD. The pest problems on vegetables can 

be more serious because of the favourable conditions which are provided for multiplication 

by the present methods of cultivation. The major constraints in vegetable production include 

the extensive crop losses due to increased pest infestation directly or due to viral diseases 

vectored by insects. The extent of crop losses in vegetables varies with the plant type, 

location, damage potential of the pest involved and cropping season.The crop losses to the 

tune of 40 per cent have observed in vegetable crops. 

Cabbage and cauliflower : 

Cabbage caterpillar, Pieris brassicae (Linnaeus) : It is distributed all along the 

Himalayan regions. It is an oligophagous pest with a limited host range of cruciferous crops 

like cabbage, cauliflower, radish, turnip, brassica oilseeds etc. 

The caterpillars feed gregariously during early stage and disperse in the fourth instar. 

The young larvae scrape the leaf surface whereas the old larvae eat up the leaves from the 

margin inwards leaving the main veins only. They skeletonize leaves and bore into heads of 

cabbage and cauliflower. 

Diamondback moth, Plutella xylostella (Linnaeus) : It is cosmopolitan in distribution 

and enjoys worldwide distribution. It is a major pest of all cruciferous vegetable crops and 

cabbage and cauliflower are major host crops. 

Larva feeds on foliage and causes serious damage by defoliation. First instar larve mine 

epidermal surface of leaves producing typical white patches. Second instar and other instars 

feed externally making holes on the leaves and soil them with excreta. Heavy infestations 

leave little more than the leaf veins. The larvae also enter the head/ curd affecting the 

production and the quality of produce. 

Cabbage head borer, Hellula undalis (Fabricius) : Cabbage head borer has world wide 

distribution. It is one of the serious pests of cruciferous crops. The larvae attack cabbage, 

cauliflower, radish, knol-khol and the weed, Gynadropsis pentaphylla (Capparidaceae).The 

pest breeds throughout the year but becomes visible when the cruciferous crops are sown. 

The caterpillars first mine into the leaves. Later on, they feed on the leaf surface, sheltered 

within the silken passages. As they grow bigger, they bore into the heads of cauliflower and 

cabbage. When the attack is severe, the plants are riddled with worms and the heads look 

deformed. 

51

Leaf webber, Crocidolomia pavonana (F.) : It is distributed throughout India, Southeast 

Asia, Australia and Africa. Leaf webber is a serious pest of cabbage, radish, mustard 

and other crucifers. 

The larvae web the leaves with silken strands and feed on the lower surface of the leaves 

completely skeletonising them. In cauliflower, larvae nibble the growing tip of seedlings and 

bore into the curd resulting in discoloration of the curd. Even a single mature larva per plant 

is capable of inflicting economic loss to cabbage at pre- and post-heading stages. 

Cabbage flea beetles : Phyllotreta cruciferae (Goeze), P. chotanica Duviv, P. birmanica 

Harold, P. oncera Maulik, P. downesi Baly: The cabbage flea beetles attack almost all the 

cruciferous plants in Europe, erstwhile USSR, North and South Amercia, Australia, Japan, 

and India. The common field crops like mustard, raya, toria, and vegetables like radish, 

turnip, cabbage, cauliflower and knol-khol are severely damaged by adult beetles. Some 

ornamental plants and flowers are also attacked. 

The adults mostly feed on the leaves by making innumerable round holes in the host 

plants. The old eaten away leaves dry up, while the young leaves are rendered unfit for 

consumption. A peculiar kind of decaying odour is emitted by the cabbage plants attacked 

by this pest. 

Cabbage aphid, Brevicoryne brassicae (Linnaeus) : Aphids in general have a very high 

rate of reproduction and a short life-span as a result of which they are serious pests of many 

economic plants. Cosmopolitan in distribution, this is a pest of cabbage, cauliflower, radish 

and many other crucifers, appearing in the cold season. 

Both nymphs and adults suck cell sap from the plants especially the tender parts resulting 

in devitalization of the plants. They also produce honeydew, which attract sooty moulds 

resulting in the hindrance in photosynthesis. In case of severe infestation plants may 

completely dry up and die away. Feeding damage from large numbers of aphids can kill 

seedlings and young transplants. On larger plants, damage results in curling and yellowing 

of leaves, stunted plant growth, and deformed heads. White cast skin will be present at the 

base of the plant. 

Cabbage semi-looper, Thysanopulsia orichalcea (Fabricius), Autographa nigrisigna 

(Walker) : These two species are widely distributed in north western India and are minor 

pests of cabbage, cauliflower and other winter vegetables. They are polyphagous and attack 

a number of plants, including groundnut and sunflower. 

The caterpillars are plump and pale green. They cause damage by biting round holes 

into cabbage leaves. On walking they form characteristic half-loops and are often seen mixed 

with cabbage caterpillars. 

Cutworms : Cutworms attack a wide variety of cultivated plants. Five species of cutworms 

namely, Agrotis ipsilon, A.flammatra, A.segetum, A.interacta and A. spinifera and A. ipsilon 

have been reported from India. The larva of A. ipsilon is commonly called greasy cutworm, 

while that of A. segetum is known as black cutworm. The young larvae feed on the epidermis 

of the leaves. As they grow, their habit changes. During the daytime they live in cracks and 

crevices in the ground and come out during night and cut the plants at ground level. The cut 

branches are sometimes seen to have been dragged into holes where leaves are eaten. 

They generally consume a little part of the plant parts and move on to attack other seedlings. 

Root crops (radish, carrot and turnip) : 

Aphids : Aphids feed on radish foliage include cabbage aphid, Brevicoryne brassicae 

52

mustard aphid, Lipaphis erysimi, peach green aphid, Myzus persicae and Toxoptera aurantii 

(Boyer de Fonsco.) The first one prefers cabbage and cauliflower; second one is a serious 

pest of crucifers. M. persicae and T. aurantii are highly polyphagous pests having a wide 

range of host plants. The colonies of aphids consisting of various stages of nymphs and 

adults suck the cell sap from tender stems and underside of leaves. The affected plant part 

fades, curl and dry up. The damage caused by sucking the sap from pods adversely affects 

the seed quality. In addition, the sooty mold which develops on the honeydew secreted by 

the aphids interferes with the normal photosynthesis of the plants. Remove and destroy the 

affected plant parts with aphids thereon. 

Economic Threshold is 10 per cent of the plants having aphid incidence on the central 

shoot in case of seed crop. 

Mustard sawfly, Athalia lugens proxima (Klug.) : It is an oligophagous pest attacking 

various winter cruciferous vegetables. The pest appears on radish leaves by the end of July 

and the activity keeps on increasing and maximum in during September to December. The 

larva is greenish-black and feeds on leaves. The damage is more pronounced on seedlings 

as compared to grown up crop. This insect has a high degree of gustatory preference for 

turnip crop. 

Flea beetles, Phyllotreta cruciferae Goeze, P. chotanica Duvier : The flea beetles are 

regular pests of crucifers. The adult beetles feed on the foliage by making holes. The damage 

is more pronounced at seedling stage. 

Leafy vegetables : Spinach is attacked by blue beetle and different species of aphids 

which are described below : 

Amaranthus weevil, Hypolixus truncatalus (F.) : Both adult and grubs cause damage. 

Grubs tunnel within the stems and branches feeding on internal tissues. Adults feed on 

tender leaves and stem but the damage is caused by adult is negligible. 

Blue beetle, Altica caerulescens (Baly) : Blue beetle has been reported as a pest of 

cabbage and spinach. Besides it it has been recorded as a minor pest on strawberry and 

plums. The grubs feed on tender cotyledon leaves as well as the fleshy older ones. Adults 

nibble the leaf margins causing very little damage. On hatching, the freshly emerged grubs 

scrap and feed on chlorophyll containing tissues, later they mine inside the leaves, feed on 

mesophyll tissues and pupate therein. 

Aphids : Lipaphis erysimi (Kaltenbach), Myzus persicae (Sulzer) and Hyadaphis 

indobrassicae (Das) have been found infesting leaves and causing damage to the crop; the 

last one being more common. These aphids are polyphagous in habit. The damage caused 

by these aphids by sucking the plant sap results in yellowing of leaves and the infested 

leaves become unfit for consumption. 

Pea 

Pea leaf miner, Chromatomyia horticloa (Goureau) : Pea leaf miner is found throughout 

the temperate region of the world. It is a polyphagous pest feeding on leguminous crops, 

cucurbits, crucifers, tomato and lettuce. The larvae make prominent whitish tunnels in the 

leaves. If the attacked leaves are held against bright light, the minute slender larvae can be 

seen feeding within the tunnels. The large numbers of tunnels made by the larvae interfere 

with photosynthesis and proper growth of plants. 

Pea stem fly, Ophiomyia phaseoli (Tryon) : It is also a polyphagous pest and feeds on 

almost all parts of beans, gram and pea. It is widely distributed in India, Srilanka, Philippines 

53

and China. The maggots on emergence feed on leaf tissue at first but later on bore into the 

terminal stems causing withering and ultimate drying of the affected shoots, thus reducing 

the bearing capacity of the host plants. The adults also cause damage by puncturing the 

leaves and the injured parts turn yellow. The damage is more serious on seedlings. 

Pea pod borer, Etiella zinckenella Treitschke : It is serious pest of green pea and 

lentils in northern India and also attacks other pulses in various parts of the country. The 

caterpillars bore inside the green pods and feed within, generally one caterpillar is found in 

one pod. The damaged pod has a large emergence hole made by the pupating larva. 

Bean aphid, Aphis craccivora Genn. : Young colonies of A. craccivora concentrate on 

growing points of plants and are often tended by ants. This symbiotic association with ants 

helps in dispersal of aphids from plant to plant. Parthenogenetic reproduction is common 

and noticed throughout the year. Both nymphs and adults suck the sap from the ventral 

surface of tender leaves, growing shoots, flower stalks and pods. The infested leaves turn 

pale yellow, the shoots wither, flower buds fall off whereas the pods shrivel and become 

deformed. Yield losses are severe when aphid colonies concentrate on the growing tips of 

the plants. Indirect damage is caused due to the production of honeydew, which hampers 

normal photosynthesis. This aphid is also known to transmit several plant viruses, leading 

to complete crop losses. 

Onion and garlic 

Onion thrips, Thrips tabaci Lindemann : It is highly polyphagous with a wide range of 

host plants in India. Besides onion and garlic, it attacks cole crops, cotton, pea, cucurbits, 

tobacco, tomato, turnip, pine apple and ornamentals like carnation, lilies and roses, etc. 

The nymphs and adults feed by lacerating the tissues and imbibing the oozing cell sap. On 

onion and garlic, they are usually congregated at the base of leaf or in the flowers. Infested 

onion develops a spotted appearance on the leaves; subsequently turning into pale white 

blotches. In case of severe attack, leaves dry from tip to downward. Development of onion or 

garlic bulb is affected to a greater extent. Thrips may also serve as vectors of some viruses 

and other plant diseases, especially the fungus, purple blotch (Alternaria porri). 

Onion maggot, Delia antiqua (Meigen) : Small maggots burrow down into the underground 

portion of stem and often into the onion bulb. Each maggot carves out a small cavity, which 

results in rotting of the bulbs in storage. Due to burrowing action, the plant withers off. The 

damage predisposes the plants to soft rot. The damage caused by the pest is generally 

followed by the attack of fungus, Bacillus carotovorus, causing soft rot of onions. Larger 

onions may survive an attack but the injured bulbs will often rot in the field or in storage. The 

attacked plants become yellowish brown from tip downwards. 

Leaf eating caterpillars : Greasy cutworm, Agrotis ipsilon (Hufnagel), tobacco 

caterpillar, Spodoptera littoralis, Fabricius and lucerne caterpillar, S. exigua (Hubner) are 

sporadic pests that cause severe damage especially to the seedlings. They are polyphagous 

pests having a wide range of host plants. Caterpillars are nocturnal in habit. Those of Agrotis 

ipsilon remain in soil during day time, come out at night and cut the seedlings at ground 

level. Caterpillars of Spodoptera species feed gregariously and move in swarms destroying 

the young seedlings and later feeding voraciously on leaves. During day time the caterpillars 

hide in hollow tubular leaves of onion but their presence is indicated by leaves and faecal 

matter. 

Another caterpillar found feeding on these crops is gram pod borer, Helicoverpa armigera 

(Hubner). Though a minor pest of onion, it has been reported causing havoc in onion crop 

54

aised for seed purpose. The caterpillars attack the umbels and feed on inflorescences, 

later they move downwards, cut the pedicels of flowers and feed on the stalks. When full 

fed, the caterpillars bore into the stalks, enter scape and pupate therein. 


Atwal, A.S. and Dhaliwal, G.S. 2005. Agricultural Pests of South Asia and their Management. 

Kalyani Publishers, Ludhiana. 

Brar, K.S. and Kaur, Ramandeep 2005. Advances in integrated pest management of vegetable 

crops (cucurbits, pea, onion and garlic). In : Advances in the Integrated Pest Management 

of Horticultural, Spices and Plantation Crops (eds. Chhillar, B.S., Kalra, V.K., Sharma, 

S.S. and Ram Singh) pp. 86-92. 

Butani, D.K. and Jotwani, M.G. 1984. Insects in Vegetables. Colour Publications, Mumbai: 

356p. 

Chadha, K.L. and Nayar, G.C. 1994. Advances in Horticulture. Malhotra Publishing House, 

New Delhi. 

Gopalakrishnan, T.R. 2007. Vegetable Crops. New India Publishing Agency, New Delhi. 

Gupta, H.C.L., Ameta, O.P. and Chechani, V.K. 2005. Management of Insect-Pests of 

Horticultural Crops. Agrotech Publishing Academy, Udaipur. 

Jotwani, M.G. and Butani, Dhamo K. 1977. Insect-pests of leguminous vegetables and their 

control. Pesticides 11 (10) : 35-38. 

Nair, M.R.G.K. 1975. Insects and Mites of Crops in India, Indian Council of Agricultural 

Research, New Delhi. 

Regupathy, A.; Palanisamy, S.; Chandramohan, N and Gunathilagiraj, K.1997. A Guide on 

Crop Pests. Sooriya Desktop Publishers, Coimbatore. 

Saxena, J.D.; Rai, S.; Srivastava, K.M. and Sinha, S.R. 1989. Resistance in the filed 

population of the diamondback moth to some commonly used synthetic pyrethroids. 

Indian J. Ent. 51 : 265-68. 

Shivalingaswamy, TM and Satpathy, S. 2007. Integrated pest management in vegetable crops. 

In : Entomology: Novel Approaches (eds Jain, P.C. and Bhargava, M.C.), New India 

Publishing Agency, New Delhi, pp 353-375. 

Srivastava, K.P. 2002. A Text Book of Applied Entomology. Kalyani Publishers, New Delhi. 

Srivastava, K.P. and Butani, D.K. 1998. Pest Management in Vegetables. Research 

Periodicals and Book Publishing House, USA. 

Sun, C.N. 1990. Insecticide resistance in diamondback moth what can we do with existing 

formulation? In : 2 nd Intl. Workshop on Management of Diamondback moth and other 

Crucifer Pests, Abstract Volume, AVRDC, Shanhua, Taiwan. 

Vastrad, A. S., Lingappa, S., Basavanagoud, K. 2004. Monitoring insecticide resistance in 

diamondback moth, Plutella xylostella (L.) in Karnataka, India. Resistant Pest 

Management Newsletter 13 (2) : 22-24. 

55

DIAGNOSTIC SYMPTOMS AND ASSESSMENT OF LOSSES 

DUE TO WHITEGRUBS IN VARIOUS CROPS 

Swaroop Singh 

Network Coordinator 

AINP on Whitegrubs & Other Soil Arthropods, Department of Entomology, 

(Swami Keshwanand Rajasthan Agricultural University) 

Agricultural Research Station, Durgapura, Jaipur 

Whitegrubs belonging to family Scarabaeidae of order coleoptera are most injurious of 

all soil pests. They are major constraint to the cultivation of rainy season (Khairf) crops and 

are pests of national importance. The severity of the damage by whitegrubs is further 

accentuated by the difficulty in their management as much of their life is subterranean. The 

immature stages, larvae (grubs) eat the roots of plants so they are also known as root 

grubs. The adults (beetles) emerge out of the soil after the premonsoon/monsoon showers 

in the month of May & June so they are also referred as May beetles or June beetles. Since 

the adults eat the leaves of trees they are also termed as leaf chafers, chaffer beetles or 

cock chafers. 

The subterranean grubs actively feed on the living roots. Being polyphagous, they feed 

on the roots of a wide variety of cultivated as well as uncultivated plants. The young grubs 

after hatching orient towards the roots and start feeding on them. Consequent to feeding, 

the plants show varying degree of yellowing; some get wilted and ultimately die. Such plants 

can be easily pulled out. The crops with tap root system suffer more as compared to those 

with adventitious root system. Almost all field crops grown during the rainy season (kharif) 

in India are damaged, viz., groundnut, sugarcane, pearlmillet, sorghum, cowpea, pigeonpea, 

greengram, clusterbean, chilli upland paddy, maize, vegetables etc. The plantation crops 

like tea and coffee suffer similar damage in their seedling and early growth stages. 

The beetles like the grubs, are also polyphagous and feed on about 250 different types 

of host trees. Sometimes the adults also cause economic damage to certain fruit, ornamental 

and other economically important trees. 

Groundnut : Groundnut is grown in kharif season (rainy season) in north India. It has 

tap root system. Those crops having tap root system is highly susceptible to whitegrub. The 

Holotrichia consanguinea is predominant species in north India. The grub finds loose, sandy 

well drained soil to be quite suitable for its survival and multiplication. The beetles of H. 

consanguinea emerge from soil during dusk after good pre-monsoon or monsoon rain. The 

mated female starts egg laying within 2-3 days of mating. The newly hatched grubs are 

creamy white in colour and may feed on organic matter for some time till they come in 

contact with living roots. Second and third instar grubs cut the root of groundnut plant, 

damaged plant show varying degree of yellowing; some get wilted and ultimately die. Such 

plants can be easily pulled out. The damage due to whitegrubs is noticed when the crop 

begins to dry up, either the whole area or in patches, after feeding by second and third instar 

grubs stage in August. Even then, the actual cause of the damage is known only when the 

soil is carefully removed around the root zone and the cut roots and grubs are seen. By 

then, the grubs have fairly grown up and have traveled to a depth of 10-20 cm below the soil 

surface. It is too late at this stage to take any preventive or curative control measures 

56

against the pest. In endemic areas, the damage ranges from 20-80 per cent the presence of 

one grub/m 2 may cause mortality of 80-100 per cent plants. 

Pearlmillet : Kharif season pearlmillet suffers from whitegrub. It has adventitious root 

system. The crops with adventitious root system suffer less as compared to those with tap 

root system. Generally the damage by whitegrub in pearlmillet is reported to be about 20-30 

per cent but some time in endemic areas, the damage is reported 80-100 per cent. Plants 

damaged by grubs show varying degree of yellowing, wilting and ultimately die. The grub 

feeds on all roots of plant so the root system is completely destroyed and such plants can 

be easily pulled out. 

Cucurbits : Cucurbits like watermelon, muskmelon, bittergourd, pumpkin etc. are heavily 

damaged by whitegrubs. In north India two species of whitegrub are found i.e. H. consanguinea 

and Maladera insanabilis. Maladera spp. has two generations in a year. It is noted that 

adults start emerging in second week of March but peak emergence takes place from April 

to early May. The beetles of second generation appear in the late June, July and August. 

The average duration of life cycle of I & II generations of Maladera insanabilis are 60 and 224 

days, respectively. The emergence of beetle takes place twice a year. Life cycle of the first 

generation is completed within 60 days. After emergence beetles settle on the nearby host 

plant like Lucerne, cucurbits or trees like rose wood, khejari, ber, babul etc. After mating, 

females lay eggs in moist, loose soil near the root zone. Newly hatched grubs feeds on 

organic matter and humus, while the second and third instars feed on cucurbit roots. The 

grubs of M. insanabilis are smaller in size and more number of grubs can be seen feeding in 

root zone of plant. Grubs cut the rootlets or roots of the plants. Such plants become yellow, 

gradually wilt and ultimately die. The damaged plant can be easily pulled out from soil. 

Cucurbit crops are damaged up to 40 per cent by the whitegrubs. 

Moongbean : Moongbean has tape root system; it is highly damaged by whitegrub. The 

second instar grubs cut the root of moongbean. The damaged plant show varying degree of 

yellowing than wilt and ultimately die. Such plant can be easily pulled out. The damage 

ranges from 20-80 per cent in the presence of one grub/m 2 . In endemic areas incidence of 

whitegrub is 80-100 per cent in moongbean. 

Vegetables : Vegetables grown during rainy season are damaged by various whitegrub 

species in different part of the country. Rainy season vegetables like chilli, tomato, brinjal 

etc. suffer more as compared to other crops. Grubs cut or feed on the roots of vegetables. 

The plant becomes gradually yellow and ultimately dies. Such plants can be easily pulled 

out. The damage symptoms of whitegrub are similar as termite. The damage ranges from 

80-100 per cent. 

Potato : The potato crop grown during summer as rainfed under long day conditions in 

higher hills is more prone to the attack of whitegrubs. In Himachal Pradesh, about 8 species 

of whitegrubs viz; B. coriacea, M. furcicauda, A. dimidiate A. polita, A. rugosa, P. dionysius, 

H. longipennis and Xylotrupes gideon (Linn.) are reported to damage potato in different areas 

of district Shimla, Solan, Sirmour, Kullu, Mandi and Chamba. The most wide spread and 

destructive species are B. coriacea, H. longipennis, Melolontha sp. and A. dimidiata. Initially 

young grubs feed on mother tuber, roots of developing potato plants, but after rubber formation, 

the older second instar and third instar grubs feed on the underground tubers by making 

large, shallow and circular holes into them and thus rendering them unfit for marketing. They 

57

live concealed while feeding on tubers and plants continue to grow normally without any 

reflection of injury on aerial parts. The grubs of B. coriacea are smaller in size and more 

number of grubs can seen feeding on a single tuber. This results in the formation of numerous 

holes on all sides of tubers. However, in case of Melolontha sp., the grubs make large 

circular hole in it. The damage has been observed to vary from 40-50 per cent, 17-28 per 

cent and 23-24 per cent in Shimla, Mandi and Sirmour, respectively. In endemic pockets like 

Shillaroo, upto 80 per cent infestation has been recorded. 

Maize : In north India, 11 species of whitegrubs viz. M. furcicauda, M. nepalensis, A. 

dimidiata, A. rufiventris, A. lineatopennis, P. dionysius, B. coriacea, L. stigma, H. longipennis, 

Heteronychus robustus Arrow and Xylotrupes gideon (Linn.), have been observed causing 

damage to maize during kharif season. The extent of damage and species composition 

varies from place to place. On an average 10-35 per cent damage has been observed by 

whitegrubs in low and mid hill areas. P. Dionysius and H. robustus cause maximum damage 

in Kullu and Solan districts, whereas, maize grown along river bed areas of Beas in Sandhol 

and Kheri areas suffer the most due to ravages of L. stigma. Certain areas of district Bilaspur 

are also suffering from the attack of this pest. The symptom of injury is root pruning by 

grubs, such plants show varying degree of yellowing, browning, wilting and eventually death. 

The grubs destroy the root system completely and such plants can be easily pulled out. 

There is uneven crop growth and the infested fields present a devastated appearance. 

Peas : There are certain ecological niches providing environmental conditions congenial 

for growing pea during kharif in higher hills. In Sangla Valley of Kinnaur (H.P.) whitegrubs 

cause 20-25 per cent plant mortality in off season crop in the month of June-July. The major 

species which were collected from different localities in Himachal Pradesh were H. longipennis, 

B. coriacea, M. furcicauda and Anomala sp. The damage was most serious in fields located 

in the vicinity of apple orchards. There was patchy growth in the infested fields and the 

damaged plants showed varying degree of yellowing, browning and wilting. The population of 

whitegrubs was very high and 4-5 grubs were found feeding on a single plant. The roots were 

totally pruned and the infested plants can be pulled out easily. The pea crop fetches premium 

price during off-season, hence whitegrub damage incurs heavy losses to farmers in this 

area. 

Cabbage : A melolonthid beetle is one of the most common cockchafer grub, occurring 

commonly in cabbage fields at higher elevations (upto 2500 meters) in Baragran area of 

Chotta Bhangal (H.P.). Apparently full fed larvae feed on cabbage roots after transplanting in 

fields and the damage is so serious that it may lead to total failure of crop in certain fields. 

The damage is most serious during July-August. Dying-off in field usually occurs as a result 

of root feeding by this pest. The symptom of injury is root pruning by grubs; such plants 

show distinct wilting, yellowing, browning and eventually death. The attacked plants show 

stunted growth and can be easily pulled out. The larvae are large thick, and measure 45 

mm. 

Ginger : Ginger is mainly cultivated in district Sirmour and is a cash crop of that area. 

Extensive survey was conducted during 2006-07 and in some localities upto 30 per cent 

infestation was recorded. Five species were collected from ginger fields, out of which H. 

longipennis and B. coriacea cause maximum damage. The damage is most serious during 

September-October. There are no symptoms of grub attack on ginger foliage and only rhizomes 

58

are attacked. The grubs make large holes in rhizomes and reduce market value of produce. 

In 2006, on in average 10.8 per cent infestation was recorded in Sangrah area. Likewise in 

2007, the incidence was more than 15 per cent in endemic areas of Sirmour district. The 

healthy rhizomes of ginger sold @ Rs. 700-800/40 kg in market, however, white grub infested 

rhizomes fetches nearly 50 per cent lesser price and are sold only @ Rs. 300-350/40 kg. 

Sugarcane : Normally sugarcane planted crop is followed by one or two ratoons. The 

long duration of the crop provides a sort of the monocropped stable agro-ecosystem for the 

multiplication of magnitude of whitegrubs. In fact the first whitegrub infestation in any crop 

in India was reported from sugarcane in 1956 in Dalmianagar area of South Bihar. The grubs 

feed on the roots and rootlets of sugarcane below the soil surface and eat away and major 

portion of the root system; some times they scoop the bottom portion of the cane stalk. In 

case of severe infestation, the whole root system gets completely depleted, and this in turn 

deprives the cane stalk from uptake of moisture and nutrient from soil, resulting in yellowing, 

wilting and ultimately death of the plant, less than threshold infestation may lead to stunted 

crop growth. The outer leaves dry up first and as the attack progresses, the entire shoot 

dries up and gets dislodged easily. Besides, it also reduces the biomass production and the 

commercial cane sugar of the crop. They also damage the clump of sugarcane, makes the 

plant susceptible to lodging in high winds resulting in plants uprooting from the soil. It 

severely reduces the yield of sugarcane. 

In the initial stages the attack of the pest occurs in patches, but later if the infestation is 

severe, the damage spreads to the whole field, each clump may harbour up to two dozen 

grubs in its root system, and if all the clumps are seriously infested, the whole crop dries up 

by August. In severe infestation, 80 per cent crop losses have been observed in sugarcane. 

In case of light infestation, particularly in crops with good growth (where the root system is 

already well developed before the infestation starts), signs of drying may be observed in the 

initial stages, but by September the crop recovers by putting fresh rootlets. The early season 

crop (October to January) is able to withstand the attack better than late-season crop or the 

spring planted crop. 

59

DIAGNOSTIC SYMPTOMS AND DAMAGE DUE TO 

INSECT-PESTS IN SOME TROPICAL AND 

SUB-TROPICAL FRUIT CROPS 

G. S. Yadav and S. S. Sharma 



A number of tropical and sub-tropical fruits are grown in different regions of India. The 

most prominent among them are mango, citrus, guava, ber, jamun, sapota etc. All the fruit 

trees are attacked by a number of insect-pests. It is very difficult to assess crop loss due to 

pest infestation and the relationship is never linear but logarithmic. The diagnostic 

characteristics and damage symptoms for some important such fruit crops have been detailed 

below. 

MANGO 

Mango hopper : Idioscopus clypealis (Lethiery), I. niveosporus (Lethiery), Amritodus 

atkinsoni (Lethiery) 

These are the most destructive pests of all the varieties of mango. Injury is caused by 

nymphs and adults, when they suck cell-sap from the inflorescence and tender shoots. 

Injury to the inflorescence and young shoots is caused by egg-laying and feeding. The 

voracious feeding nymphs are particularly harmful. They cause the inflorescence to wither 

and turn brown. Even if the flower are fertilized, the subsequent development and fruit setting 

may cease. In thick and protected gardens where the atmosphere is humid, a sooty mould 

develops on patches of honeydew exuded by the nymphs. As the wind blows, young fruits 

and dried inflorescence barkoff at the axil and fall to the ground. The growth of young tree is 

much retarded and the older trees do not bear much fruits. Damage to the mango crop is as 

high as 60 per cent. 

Mango mealybug- Drosicha mangiferae (Green) 

Besides mango, it also attacks 62 other plants, including such trees as jack fruit, banyan, 

guava, papaya, citrus and jamun. 

This pest is active from December to May and spends rest of the year in the egg stage. 

Among insect pests of mango, the mealybug occupies an important place. Only the nymphs 

are destructive and they suck the plant sap, causing tender shoots and flowers to dry up the 

young fruit becomes juiceless and drop off. The pest is responsible for causing considerable 

loss to the mango growers and when there is a serious attack the trees retain no fruit at all. 

Mango stem borer: Batocera rufomaculata De Geer; B. rubus. Linnaeus. 

They have been recorded as serious pests of mango, fig and other trees in north-western 

parts of the Indian-subcontinent. Although the borer is not very common, yet whenever it 

appears in the main trunk or a branch, it invariably kill the host. Though the external symptoms 

of attack are not always visible, the site can be located from the sap or frass that comes out 

of the hole. The mango stem borer is also found in newly fallen trees. 

Mango stone weevil: Sternochetus mangiferae (Fabricius) 

The export of mango fruits from India to USA has been banned to prevent the entry of this 

60

DIAGNOSTIC SYMPTOMS OF INSECT-PESTS' DAMAGE IN FRUIT TREES 

Bark eating caterpillar 

Guava fruit fly 

Ber fruit fly 

Citrus leaf miner 

Citrus psylla Citrus caterpillar 

Mango mealybug 

Mango hopper

weevil. The insect attack mango varieties with a relatively soft flesh. However, it is not very 

serious in any part of the country. The injury caused by the larvae feeding in pulp sometimes 

heals over but a certain number of fruits always get spoiled when the weevil make an exit 

through ripe or near ripe mangoes. 

Mango bud mite – Aceria magniferae Sayed 

In India, the mite is serious particularly in Punjab, Haryana and Uttar Pradesh. 

The bud-mite sucks the sap from inside the buds and causes necrosis of tender tissues. 

When the population is high, the entire bud may be killed. This mite infests all varieties of 

mango and none has shown resistance to it. 

CITRUS 

Citrus psylla: Diaphorina citri Kuwayana 

It is the most destructive of all the citrus pests. Damage is caused by nymphs and 

adults. The pest is active throughout the year but its life-cycle greatly prolonged in the 

winter. The most favourable conditions for development are found in the month of March. 

Although there is a visible difference in the rise and fall of its population in various 

seasons, yet the ill-effects of its damage are so-long lasting that the trees may look sickly 

even when the population is not high. Thus, sooty and sickly plants seen in the winter are 

victims of insects which caused damage during the previous summer. 

Only the nymphs are harmful to the plants. With the help of their sharp piercing mouth 

parts, they suck the cell-sap. The vitality of the plants deteriorates and the young leaves 

and twigs stop growing further. The leaf-buds, flower buds and leaves may wilt and die, 

whatever little fruit is formed in the spring fall off prematurely. Moreover, the nymphs secrete 

drops of a sweet thick fluid on which a black fungus develops adversely affecting 

photosynthesis. It is also thought that insect produces a toxic substance in the plants as a 

result of which the fruits remain undersized and poor in juice and insipid in taste. This insect 

is also responsible for spreading the greening virus. If the pest is not checked in time, the 

entire orchard may be lost, and after a year or two of continued damage, the plants may be 

killed. 

Citrus Whitefly: Dialeurodes citri (Ashmead) 

Although it is a pest of citrus, the insect prefers to feed on certain deciduous plants 

such as persimmon and dharek. Damage is caused by both adults as well as by nymphs. 

The pest causes the damage in the nymphal and adult stages. It sucks the cell-sap from 

leaves which curl over and fall off. The honey dew excreted by the nymphs is a very good 

medium for the growth of a sooty mould, which interferes with photosynthesis. Thus, the 

trees infested with this pest deteriorates further. It has been noticed in California that a 

heavy infestation of whitefly is apt to be followed by increase in the red scale of citrus, 

because the young scales collect under the powdery wax of whitefly for protection against 

bright light. 

Citrus mealybug, Pseudococcus filamentosus Cockerell 

The mealy bugs are known to feed on a number of plants, often not closely related to 

citrus. In the gardens, they are seen on Cactus spp., ferns, begonia, gardenia, poineseffia 

and other flowers. 

61

Damage is caused by both nymphs and females. The insect feed on cell sap and the 

plants becomes pale, wilted and the affected parts eventually die. The insect also excrete 

honeydew on which a mould grows, which interferes with photosynthesis. Black ants are 

attracted to the honeydew and they become a nuisance. In severe cases of infestation, the 

citrus flowers do not set fruits. 

Citrus caterpillar: Papilio demoleus Linnaeus 

It can feed and breed on all varieties of cultivated or wild citrus and various other species 

of the family Rutaceae. Only the caterpillars cause damage by eating the leaves. The larva 

show preference for young and shiny leaves of citrus. After making a full meal, they remain 

motionless while exposed, usually near the mid-rib. Habitually, they feed from the margin 

inwards to the midrib. In later stages, they feed even on mature leaves and sometimes the 

entire plant may be defoliated. 

The pest is particularly devastating in nurseries and its damage to foliage seem to 

synchronize with fresh growth of citrus plants in April and August-September. Heavily attacked 

plants bear no fruit. 

Citrus leaf miner: Phyllocnistic citrella Stainton 

Apart from citrus, the insect also feeds on variety of other plants such as pomelo, willow, 

annamon and Laranthus spp. 

Damage by this mining pest is serious on young leaves. The injured epidermis takes the 

shape of twisted silvery galleries. On older leaves, brownish patches are formed which serve 

as foci of infection for citrus canker. The attacked leaves remain on the plants for a 

considerably long time and the damage gradually spreads to fresh leaves. Heavily attacked 

plants can be spotted from a distance and young nurseries are most severely affected; the 

young plants of orange and grape fruit may not even survive; the photosynthesis is adversely 

affected, vitality is reduced and there is an appreciable reduction in yield. 

Fruit sucking moths: Ophiders spp. Cramer 

The fruit moths are minor pests of citrus, mango, grapes and apple and are distributed 

throughout India. They are reported to be in abundance near the forests or other natural 

vegetation. The presence of moths in a locality is observed from the characteristic pin-hole 

damage in citrus and other fruits. 

Unlike most moths and butterflies, the fruit-piercing moths cause damage in the adult 

stage. With the help of its strong piercing mouthparts, moth punctures the fruit for sucking 

juice. Bacterial and fungal infections take place at the site of attack with the result that the 

brownish mouth of puncture becomes pale and eventually the whole fruit turns yellow. It 

drops off the tree and apparently looks like a premature fruit. If the damaged fruit is squeezed, 

the juice spurts from the hole. In severe case of infestation, almost all the fruits are lost. 

GUAVA 

Guava fruit fly: Bactrocera dorsalis (Hendel) 

Apart from mango, the pest also feeds on guava, peach, apricot, cherry, pear, chiku, ber, 

citrus and other plants, totaling more than 250 hosts. This pest is active during summer 

months. 

Damage is caused by grubs and they feed on fruit pulp, making the fruit unfit for human 

consumption. The infested fruits become unmarketable and at times almost all of them 

contain maggots. 

62

Bark eating caterpillar: Indarbela tetraonis (Moore); Indarbela quadrinotata (Walker) 

It also feeds on mango, citrus, jamun, loquat, mulberry, pomegranate, ber, drumstick, 

litchi, amla, rose and a number of forest and ornamental trees. 

Thick, ribbonlike, silken webs are seen running on the bark of the main stem especially 

near the forks. The larvae also makes holes and as many as 16 holes may be seen on a 

tree, one caterpillar or pupa occupying each hole. A severe infestation may result in the 

death of the attacked stem but not of the main trunk. There may be interference with the 

translocation of cell sap and thus arrestation of growth of the tree is noticed with the resultant 

reduction in it’s fruiting capacity. 

Guava mealy scale: Chloropulvinaria psid i (Maskell) 

Apart from guava, the scale feeds on coffee, tea, citrus, mango, gular, jack fruit, jamun, 

litchi, loquat, sapota and many other shrubs and trees. 

The scale insects are found in large numbers sticking to leaves on ventral side, tender 

twigs and shoots. They suck sap from ventral side of leaves, petioles, tender shoots and 

occasionally from fruits. They cause leaf distortion and growth disturbance. The female 

feeds voraciously and also exude copious quantity of honeydew. The honeydew excreted by 

the scales encourages the development of sooty mould on foliage which interferes with 

photosynthetic activity of plants and spoils the market value of fruits. Severe infestation 

could kill the branches. 

BER 

The ber, which is one of the most common fruit trees of Indian sub-continent, is grown 

on about 10,000 hectares. It is often called poor man’s fruit. In India, as many as 80 insect 

species feeding on ber tree have been reported, out of which fruit fly and ber, beetle are 

important. The former causes serious damage to fruits and the latter is a foliage feeder and 

shows preference for ber trees. Both are basically polyphagous insects and have also been 

recorded feeding on a number of fruit trees, but ber seems be the preferred host. 

Ber fruitfly Carpomyia vesuviana Costa 

This pest is widelydistributed in India, Pakistan and southern Italy. It.is most destructive 

to ber fruits of the species Zizyphus mauritiana and Z.jujuba Mill in India and Z. sativa in 

Italy. Also, C.vesuviana ,Bactrocera dorsalis (Hendel) and B. correctus have been recorded 

as minor pests of ber fruits. 

The pest is active during winter and hibernates in the soil from April to August in the 

pupal stage. The flies emerge from the pupae during August to mid-November, synchronizing 

with the blossoming and fruit setting of the ber. 

At the fruit age of one month, the flies make cavities in the skin of fruit and lay one or 

two spindle- shaped creamy-white eggs below the skin, leaving behind a resinous material. 

There is no further growth of the fruit in the vicinity of this puncture and hence, the fruits 

become deformed. The eggs hatch in 2-3 days and the maggots feed on the flesh of the fruit, 

making galleries towards the centre. Such fruits invariably rot near the stones and as many 

as 18 maggots have been recorded from one attacked fruit. The pest becomes active in the 

autumn and builds up population in the winter, reaching a peak in February-March. At that 

time all the late-maturing ber fruits are found riddled with maggots. Fleshy varieties of ber 

are more seriously damaged than the less fleshy ones. The attacked fruits are rotten near 

the stones and emit a strong smell. Late maturing fruits are destroyed almost entirely. 

63

Ber Beetles 

Adoretus pallens Arrow and A. nitidus Arrow 

These two defoliating beetles are widely distributed in northern India and Pakistan. and 

are polyphagous but they prefer the ber tree (Zizyphus jujuba) and the grapevine. Only the 

adult beetles are destructive and can be recognized from their bright yellow color and 

yellowish-brown shiny wings, The beetles are attracted to light and appear in large numbers 

late in spring or early summer and again during the monsoon. This pest is active during 

summer and passes the winter in larval stage. The adults appear in April-May and lay white, 

smooth, elongate eggs singly in the soil near the host plants. The whitish grubs feed on soil 

humus, roots of grasses and other vegetable matter found under or near the ber trees. When 

full-grown, the grubs measure 15 mm in length and are creamy white. They make an earthen 

cell in the autumn and hibernate through the whole of winter. There is only one generation in 

a year. Damage is characterized by round holes cut in the leaves by beetles during the 

night. The ber trees are sometimes so heavily attacked that the entire foliage may disappear 

and such trees do not bear any fruit. The attack starts early in the spring and continues up 

to August. 

POMEGRANATE 

Anar Butterfly, Virachola isocrates (Fabricius) 

The caterpillars of the Anar butterfly cause such a heavy damage to the fruits that this 

pest alone is responsible for the failure of pomegranate crop in certain areas. This insect is 

widely distributed all over India and the adjoining countries. It is a polyphagous pest having 

a very wide range of host plants including Aonla, apple, ber. citrus, guava, litchi, loquat, 

mulberry, peach, pear, plum, pomegranate, sapota and tamarind. The caterpillars bore inside 

the developing fruits and feed on pulp and seeds just below the rind. 

The caterpillars damage the fruit by feeding inside and riddling through the ripening 

seeds of pomegranate. As many as eight caterpillars may be found in a single fruit. The 

infested fruits are also attackd by bacteria and fungi which cause the fruits to rot. The 

affected fruits ultimately falloff and give an offensive smell. This pest may cause from 40 to 

90 per cent damage to the fruits. 


Atwal, A.S. and Dhaliwal, G.S. 1997. Agricultural Pests of South Asia and their Management. 

Kalyani Publishers. pp. 461. 

Verma, L. R.; Verma, A. K. Gautam, D. C. (eds.). 2004. Pest Management in Horticultural 

Crops. Asiatech Publishers Inc. pp. 376. 

Singh, P. and Mann, G. S. 2003. Effect of fruit maturity on the infestation of oriental fruit fly, 

Bactrocera dorsalis (Hendel) in different cultivars of peach, pear and guava. J. Insect 

Sci. 16 (1-2) : 52-54. 

64

DIAGNOSTIC SYMPTOMS AND ASSESSMENT OF 

LOSSES DUE TO ARTHROPOD PESTS IN TROPICAL 

FRUIT CROPS INCLUDING SOME PLANTATION CROPS 

G. M. Patel 

Dean, College of Basic Science and Humanities 

S. D. Agricultural University, Sardarkrushinagar 

India is bestowed upon with such a varied climatic condition that almost all kind of fruits can 

be commercially in India for past several years. Area under fruit crops is increasing year after 

year but production grown in one or the other part –tropical, subtropical and temperate. Over two 

dozen fruits are grown of the fruits is still not up to satisfactory level. The horticulturists have 

evolved high yielding varieties of fruits and their production technologies but the research on 

‘protection’ is not sufficient and therefore, till today farmers suffer heavy losses due to insect 

pests and diseases. For this purpose, basic knowledge of diagnostic symptoms and assessment 

of losses due to arthropod pests of tropical fruits is discussed here. 

I. Mango : Mangifera indica Linnaeus 

Over 175 species of insect pests have been reported damaging mango trees(Fletcher, 

1917 and Nayar et al., 1976) Important pests of mango are mango hoppers, mango mealy 

bugs, mango stem borer, scale insects fruit flies, bark eating caterpillar, gall midges and 

termites and mango stone weevil. 

1.1 Mango hoppers : 

Symptoms of damage : Female inserts eggs in the main vein causing curling up of 

such leaves. Both adult as well as nymphs suck cell sap and excrete honey dew which 

attract growth of black sooty mould which hampers photosynthesis. Presence of bugs reduce 

market price of fruits. 

Extent of losses : Rao (1930) estimated 20 to 100 per cent losses due to hopper incidence 

in inflorescences, while Chema et al. (1954) and Gangolly et al. (1957) reported it to 25 to 60 

per cent. 

1.2 Mango mealy bugs : Drosicha mangiferae (Green) 

Symptoms of damage : The mealy bug adult as well as nymphs suck cell sap and 

excrete honey dew which attract growth of black sooty mould which hampers photosynthesis. 

Presence of bugs reduce market price of fruits. 

1.3 Mango stem borer : Batocera rufomaculata 

Symptoms of damage : Grubs make zig-zag burrows beneath bark and tunnel into the 

trunks or main stem, feeding on the internal tissues. When grub reach sapwood, the affected 

stem/ branch die and wither. Shedding of leaves, sap and masses of frass exuding from the 

bored holes are other symptoms of damage. Eventually the infested branch/ stem die and 

dry up. 

1.4 Scale insects : Icerya purchasi Maskell 

Aspidiotus destructor Signret 

Symptoms of damage : The nymphs as well as adult s suck the plant sap causing 

substantial quantitative as well as qualitative losses in fruit yield. 

65

1.5 Mango fruit fly : Dacus dorsalis(Hendell) 

Symptoms of damage : Infests mango (April- July), guava(August-March), loquat, apricot, 

plum(April –May), peach and fig (June). Maggots feed on the pulp of ripening fruit. Brown 

patch appears around oviposition hole. Affected fruits drop prematurely. 

1.6 Mango stone weevil : Sternochetus mangiferae (Fabricius) 

Symptoms of damage : The female lays eggs on premature fruits beneath the peel. 

The grub on hatching makes its way through the endocarp and enters the seed and feed on 

cotyledon. Real damage is done by the weevil while escaping from the stone through the 

pulp by soiling it and making it unfit for human consumption. 

1.7 Mango shoot borer : Chlumetia transversa Walker 

Symptoms of damage : Terminal shoots show tunnel from top to down wards. Stunting 

of seedlings with terminal bunchy appearance. 

2. Banana : Musa spp. 

Simmonds (1966) have published a list of 182 insect pests infesting banana on global 

basis, however, only few of them attack this crop in India. The major pests infesting banana 

in our country are banana weevil, banana stem borer and flea beetle. 

2.1 Banana weevil : Cosmopolitan sordidus (Germar) 

Symptoms of damage : Eggs are laid in collar region (above ground) or rhizomes 

(underground). Soon after hatching, the grubs bore into the stem of the same stool and feed 

within. Pupation is usually in the soil. Adults are sluggish and avoid day light, hiding in leaf 

sheaths and rotting pseudo stems where humidity is very low. They feed during night on the 

pseudostem and bore in to suckers. The attacked pseudostems get riddled with holes and 

the root origins are weakened. Secondly, the tunnels made by these weevils are occupied 

by fungi and bacteria which result in rotting of attacked pseudostem. With strong blast of 

wind, the plants break down from the point of infestation. If the fruits are formed, very few in 

numbers and inferior in quality (Sen and Prasad, 1953). 

2.2 Banana stem borer : Odoiporus longicollis (Olivier) 

Symptoms of damage : The grubs start feeding on tissues around the air chambers of 

leaf sheath and then bore inside the pseudostem. A number of grubs may be found boring a 

single plant. The pseudostem thus riddled become weak and start rotting. Ultimately, with 

strong blast of wind, the plants break from the point of infestation. The estimated yield loss 

due to this pest is between 10 – 90% depending on the growth stage in which the infestation 

occurs and it is the highest in 5 months old crop. 

2.3 Flea beetle : Nodostoma subcastatum Jacoby N. viridipennis Motschulsky 

Symptoms of damage : Grubs are found underground near the roots, while the beetles 

are found feeding on leaves and fruits. The central leaves forming the top whorl are the worst 

affected. In case of fruits, the beetles scratch the skin of the newly formed fruits- thus the 

fruits are blemished and flavour spoiled, reducing thereby the market value of such fruits. 

Roy and Sharma (1952) observed nearly 80 per cent of banana bunches attacked by this 

pest during rainy season at Sabour (Bihar). 

2.4 Banana aphid : Pentalonia nigronervosa (Coquerel) (Aphididae : Homoptera) 

Symptoms of damage : Nymphs and adults suck the sap causing deformation of plants. 

The leaves become curled and shriveled and in case of severe infestation young plants are 

killed. Feeding also results in honey dew secretion on which the sooty mould grows resulting 

in decrease of photosynthetic activity and vigour of the plant. It is a vector of the “bunchy top 

disease” in banana and “Katte disease” in cardamom. 

66

3. Pomegranate : Punica granatum 

Pomegranate trees are attacked by about 45 species of insect pests in India. Fruits are 

more vulnerable to attack of pests than any other parts of the tree. 

3.1 Anar butterfly Deudorix (=Virachola) isocrates F. ) (Lycaenidae : Lepidoptera) 

Nature of damage : The female lays eggs singly on calyx of flowers or small fruits. On 

hatching, the caterpillars bore inside the developing fruits and are usually found feeding on 

pulp and seeds(arils) just below the rind. As many as eight caterpillars may be found in a 

single fruit. Subsequently, the infested fruits are also attacked by bacteria and fungi causing 

the fruits to rot. The conspicuous symptoms of damage are offensive smell and excreta of 

the caterpillars coming out of entry holes, the excreta are found stuck around the holes. 

Sometimes the holes may also be seen plugged with the anal end of a caterpillar. The 

affected fruits ultimately fall down and are of no use. 

3.2 Fruit borer : Conogethes punctiferalis (Guenee) 

Symptoms of damage : 

Caterpillar bores into young fruits 

Feeds on internal contents (pulp and seeds) 

Dry up and fall off in without ripening 

3.3 Green Scale, Coccus viridis 


Nymphs and adults suck the sap from leaves 

Yellowing of leaves. 

3.3 Tailed mealy bug : Ferrisa virgata 

Symptoms of damage : Premature dropping of fruit. 

3.4 Pomegranate aphids : Aphis punicae 

Symptoms of damage 

Nymphs and adults suck the sap from leaves, shoots and fruits 

Yellowing of leaves 

Wilting of terminal shoots. 

4. Pests of Guava : Psidium guajava Linnaeus 

4.1 Guava fruit fly : Bactrocera diversus (Coquillett) 

Symptom of damage : 

Adults and maggots attack semi – ripe fruits 

Oviposition punctures on fruits 

Maggots destroy and convert pulp into a bad smelling 

Discoloured semi liquid mass 

4.2 Bark borer, Indarbela tetraonis (Moore) 


Young trees may succumb to the attack 

Caterpillars bore into the trunk or junction of branches 

Caterpillars remain hidden in the tunnel during day time and come out at night, feed 

on the bark. 

Presence of gallery made out of silk and frass 

67

Estimation of losses : Investigations were undertaken from 1999-2003 at Institutes farm 

of Central Institute for Subtropical Horticulture, Lucknow, India and result indicated that the 

incidence of Deudorix isocrates was at its peak on cv. L-49 in the month of August in rainy 

crop, while in winter crop it was more during November/December. The incidence ranged 

from 3.0 to 38.0 per cent during these periods. Losses in fruit weight were found directly 

proportional to the extent of infestation by the borer (Haseeb and Sharma,2007). 

4.3 Guava Fruit Borer : Congethes (=Dichocrocis) punctiferalis (Guenee) 


Caterpillar bores into young fruits 

Feeds on internal contents (pulp and seeds). 

Attacked fruits dry up and fall off without ripening. 

Tea mosquito bug: Helopeltis antonii Signoret 

Nymphs and adults make punctures on petiole, tender shoots and fruits 

Brownish – black necrotic patches develop on foliage 

Elongate streaks and patches develop on shoots 

Corky scab formation on fruits 

5. Pests of Sapota or Chickoo : Achras sapota Linnaeus 

5.1 Chickoo moth : Nephopteryx eugraphella Ragonot 

Nature of damage : The caterpillars generally feed on leaves but are often found to 

attack buds, flowers and sometimes tender fruits as well. The caterpillars web together a 

bunch of leaves and feed within on chlorophyll, leaving behind a fine net work of veins. They 

also bore in to flower-buds and tender fruits which wither away and the caterpillar move on to 

next bud or fruit. 

5.2 Chickoo Bud moth, Anarsia epotias 


Bores and web flowers and buds 

Shedding of buds and flowers. 

Bore holes and excreta seen on attacked flowers. 

5.3 Leaf eating caterpillar : Metanastria hyrtaca (Cramer) 


Caterpillars feed on leaves 

Defoliation 

6. Pests of date palm : Phoenix dactylifera Linnaeus 

About 13 insect species have been found damaging date palms in India. 

6.1 Rhinoceros beetle : Oryctes rhinoceros (Linnaeus) 


Central spindle appears cut or toppled 

Fully opened fronds showing characteristic diamond shaped cuttings 

Holes with chewed fibre sticking out at the base of central spindle. 

68

6.2 Red palm weevil : Rhynchophorus ferrugineus (Olivier) Identification 


Holes on trunk with with brownish ooze 

Yellowing of inner leaves 

Gradual wilting of central shoot in the crown 

6.3 Bark weevil : Dicalandra stigmaticolis 

Symptoms of Damage : 

Reddening of petioles and trunks especially around wounds. 

Trees with stem bleeding disease. 

6.4 Black headed caterpillar : Opisina arenosella (Meyrick) 

Symptoms of Damage : 

Dried up patches on leaflets of the lower leaves· 

Galleries of silk and frass on underside of leaflets. 

6.5 Scale insect : Aspidiotus destructor 


Yellowing of leaves in patches, later coalescing together 

6.6 Mealy bug : Pseudococcus longispinus 


Central leaves stunted, deformed and suppressed 

Shedding of buttons 

6.7 Coconut Eriophyid mite : Aceria guerreronis 


Triangular pale or yellow patches close to perianth 

Necrotic tissues 

Brown colour patches, longitudinal fissures and splits on the husk 

Oozing of the gummy exudation from the affected surface 

Reduced size and copra content 

Malformed nuts with cracks and hardened husk. 

7. Custard apple : Annona squamosa Linnaeus 

7.1 Fruit borer : Heterographis bengalella (Ragonot) 


Caterpillar bore into the fruits and make tunnel inside 

Feed on the internal content of the fruits 

Affected fruits fall to ground 

7.2 Fruit fly : Bactrocera zonata 


Maggot bore into the semi ripened fruits 

Feed on the inside fruits 

Affected fruits – shriveled, malformed, rot and fall off 

69

7.3 Tailed mealy bug : Ferrisa virgata (Cockerell) 


Adults and crawlers – setting on leaves, young shoots and fruit (between segments) 

Yellowing of leaves 

Reduction of fruit size and do not fetch premium price in the market. 

8. Pests of Citrus 

8.1 Citrus caterpillar/Lemon butterfly : Papilio demoleus Linnaeus 

Symptoms of damage : Under favourable conditions, this can be serious insect under 

nursery conditions and in young orchards. Larvae appear like bird dropping in early instars. 

Full-grown larva turns green. Leaves are eaten from the edges to the midrib. In case of 

severe attack, only midribs are left behind. Complete defoliation may occur resulting in 

stunted growth of the plant. Caterpillar, when feels threatened or frightened, produces a jet 

of fluid having strong odour from a fleshy organ (shaped like a snake tongue) behind the 

head known as osmeterium. This is a natural defense mechanism in this insect Peak activity 

period: April-May and August-October 

8.2 Citrus leaf miner : Phyllocnistis citrella 

Symptoms of damage : This is the most harmful insect of citrus nursery. Its infestation 

coincides with the flush periods. Larvae feed in epidermis of leaves making serpentine silvery 

mines usually on the ventral side. When the infestation is severe, mines also appears on 

dorsal side of the leaves. The serpentine mines appear silver coloured because air is 

entrapped in these mines. Tiny pupae can be seen in the damaged leaf in the mines. Such 

leaves are folded from the edge due to spinning of cocoons by the larvae. Leaves get distorted, 

crumpled and curled from margins towards inner side. Ultimately, the damaged leaves dry 

up and fall down Mines appear on tender twigs also. Severe defoliation may occur, which 

results in reduced growth of nursery plants. The leaves folded due to damage by leaf miner 

serves as shelter site for mealy bugs, grey weevil, citrus psylla and spiders. This insect 

enhances citrus canker disease. 

Peak activity period : Last week of April to mid June and last week of July to mid October. 

8.3 Citrus white and Black fly : Aleurocanthus woglumi(Ashby) 

Dialeurodes citri (Ashmead) 

Symptoms of damage : Both nymphs and adults suck plant sap and reduce the vigour 

of the plant. Severely infested foliage turns pale green to brown. Foliage may also become 

curled and ultimately shed. Infested tree gives blackish appearance due to sooty mould 

growing on honeydew. Few flowers are produced on such trees and fruits developing from 

such flowers have insipid taste. White and black pupae of whitefly and blackfly, respectively 

can be seen on the underside of the leaves. 

Peak activity period : April-May and September-October 

8.4 Citrus Fruit Sucking moth : Eudocima fullonia (Clerck) 

Eudocima materna (Linnaeus) 

Damage symptoms : The caterpillars are leaf defoliators and generally found on wild 

creepers of menispermaceae and anacardiaceae families apart from some economic crops 

like castor, ber, pomegranate etc. 

Adult moth sucks the juice of ripening fruits after dusk (sun set) during the rainy season. 

The moths have a strong proboscis with sharp spines with which they pierce the ripening 

fruits. A circular pinhole like spot appears at the feeding site. Later on, the area around the 

70

damaged portion turns yellowish-brown. On squeezing such fruits, a jet of fermented juice 

comes out. The punctured fruits are easily infected with bacteria and fungi. As a result, the 

fruit rot and falls prematurely. E 

Estimated losses : 3 to 5 per cent fruits are damaged by moths every year. 

Peak activity period : July to October (mainly in the sub-montaneous zone of Punjab, 

particularly in the Kandi belt of District Hoshiarpur and Pathankot area of District Gurdaspur 

near the forest areas). 

8.5 Citrus psylla : Diaphorina citri Kuwayama 

Damage symptoms : Both the nymphs and adults suck plant sap. Nymphal stage causes 

more damage than the adult stage. Heavy de-blossoming may occur. Leaves show chlorotic 

symptoms. Size of the leaves gets reduced and leaves become distorted and curled. The 

infested twigs die-off from tip backward, probably due to toxin released by psylla during 

feeding. This insect excretes honeydew, which is covered with a waxy secretion of circumanal 

glands. In case of severe damage, waxy material falls under tree on ground giving the ground 

a whitish look. Unlike secretions by aphids and scale insects that results into growth of 

sooty mould, honeydew excreted by psylla does not results in deposition of sooty mould on 

leaves. Ants can be seen commonly moving at the site of infestation. It is a vector of 

greening disease (caused by a bacterium) and one of the major factors for citrus decline. 

9. Pests of Coffee (Coffea arabica) 

9.1 Coffee white borer, Xylotrechus quadripes Ch. (Cerambycidae: Coleoptera) 

Nature of damage : The grubs burrow into the stem for 8 - 9 months and cause wilting 

of branches and occasionally death of bushes. It is a serious pest of Arabica coffee. Infested 

plants show external ridges around the stem. Affected plants also show yellowing and willing 

of leaves. 

9.2 Coffee Berry Borer, Hypothenemus hampei (Ferrari) (Scolytidae: Coleoptera) 

Nature of damage : Pin holes at the tip of berries. In severe cases of infestation two or 

more holes may be seen. Infested berries may fall due to injury or secondary infection. 

Severe infestation may result in heavy crop loss up to 40 - 80%. 


Chema G. S., S. S. Bhat and K. C. Naik. 1954.Commercial Fruits of India, 422 pp. 

Macmillan & Co. Ltd. , Calcutta.Fletcher, Bainbrigge T.1917. Fruit –trees. Rept. Proc. 2nd Ent. Mtg. Pusa (Bihar), February 1917 : 209-257, Calcutta. 

Gangolly, S. R., Ranjit Singh, S. L. Katyal and Daljit Singh. 1957. The Mango, 530 pp. 

Indian Council of Agricultural Research, New Delhi. 

Nayar, K. K., T. N. Ananthakrishanan and B. V. David. 1976. General and Applied Entomology., 

589 pp. Tata Mac Graw- Hill Publishing Co. Ltd., New Delhi. 

Rao, Y. Ramchandran.1930. The mango hopper problem in South India. Agric J. India., 

25 (1) : 17-25, Pusa (Bihar). 

Roy, R. S. and Chandeshwar Sharma. 1952. Diseases and pests of bananas and their control. 

Indian J. Hort. 9 (4) : 39-52,New Delhi. 

Sen, A. C. and D. Prasad. 1953. Pests of Banana in Bihar. Indian J. Ent., 15 (3) : 240-256. 

71

DIAGNOSTIC SYMPTOMS AND LOSS ASSESSMENT 

DUE TO INSECT-PESTS IN COTTON 

K. K . Dahiya 

Department of Genetics and Plant Breeding, 

CCS, Haryana Agricultural University, Hisar-125 004 

Cotton is the most important commercial crop of our country contributing upto 75% of 

total raw material needs of textile industry and provides employment to about 60 million 

people. Cotton is attacked by several insect pests reducing the crop yield to a greater 

extent. The insect pests that attack cotton crop may be classified into sap sucking insects 

or chewing insects. 

SUCKING INSECT-PESTS : 

Sucking pests of cotton can infest a crop from the time of seedling emergence. They are 

able to reduce the yields of cotton as pests in their own right - but usually only if their 

population densities are enhanced by the misuse of insecticides. Sucking pests are often 

induced pests. Farmers are known to react to their presence and apply an insecticide in an 

attempt to kill them, irrespective of whether they have any potential to reduce yields. This 

brings forward the first insecticide application of the season and reduces the number of 

natural control agents in the fields that would or could have eaten or parasitised the bollworm 

eggs and larvae that arrive later in the season. This earlier-than-necessary insecticide 

application is the first step in the seasonal pesticide treadmill that results in the build up of 

insecticide resistance within and between crop cycles. Aphid, leafhopper and whitefly in 

particular are seen as ‘predator fodder’ and as such have an important role to play as 

attractants to the ladybirds. 

Leafhopper : Amrasca biguttlla biguttlla : Leafhopper is a polyphagous insect pest. 

Both nymphs and adults cause damage by sucking the cell sap. The attacked leaves turn 

pale and than rusted red and leaves may turn to cup shape (down side) and dry up. In case 

of severe attack, plant vitality is affected and cotton bolls may also drop off. The population 

is considered to be serious if 2 or more than 2 nymphs per leaf are observed or if 20 percent 

of the leaves start showing the yellowing symptoms from the edge of the leaves. 

Cotton Whitefly, Bemisia tabaci : Cotton whitefly is a polyphagous insect pest with 

wide host range. Damage is done by sucking the cell sap from the leaves resulting the loss 

of vitality of the plant. Normal photosynthesis is affected due to growth of sooty mould on 

honeydew deposited on dorsal surface of the leaves; consequently the growth of the plant 

and yield is affected. Cotton white fly also transmit the cotton leaf curl virus and the veins of 

diseased leaves got thickened and later on leaves becomes cup shaped (up side) and another 

leaf is emerged from the leaf. 

Thrips, Thrips tabaci : Nymphs and adults are the damaging stage. Nymphs do maximum 

damage by rasping and sucking the sap from the veins of the leaves which ultimate dry up 

Dry weather favuors the multiplication of thrips. 

Mealybug : The insect feeds on sap of the plant preferably on the central twig and than 

on other plant part and releases toxic substances causing injury, curling and drying of the 

72

DIAGNOSTIC SYMPTOMS OF INSECT-PESTS' DAMAGE IN COTTON 

Leafhopper 

Helicoverpa armigera Mealybug 

Earias spp. 

Thrips Whitefly 

Red cotton bug 

Cotton leaf roller 

Termite 

Spodoptera litura 

Pink bollworm 

Dusky cotton bug 

Blister beetle

leaves. It also secrets copious quantity of honeydew on to the plant that in turn attracts ants 

and sooty mould.Plant may show on or more of the following symptoms like crinkled/twisted 

leaves and shoots, bunched or unopened leaves, distorted or bushy shoots, white fluffy 

mass on buds and stem, presence of honey dew, black sooty mould, unopened flowers 

which often shrivel and dieand small deformed bolls etc. 

Dusky Cotton Bug, Oxycarenus laetus Damage is done by sucking the cell sap from 

immature seeds thus the seeds may not ripe, loose color and remain light in weight. Adults 

get crushed at the time of ginning in cotton thus stain the lint and lower its market value. 

Red Cotton Bug Dysdercus koenigii : Damage by the pest is done by sucking the cell 

sap from leaves and green bolls of cotton. The lint from the affected bolls is of poor quality. 

Seeds produced from the affected bolls may have poor germination and less oil. Bugs stain 

the lint with excreta or body fluid as they are crushed in the ginning factories Due to the 

attack of the pest, bacterial growth also takes place. 

Aphid, Aphis gossypii is a polyphagous pest. Nymphs and adults of aphid cause damage 

by sucking the cell sap from twigs and leaves. Aphids also secrete the honeydew, which 

covers the dorsal surface of the leaves and on the leaves. Due to development of sooty 

mould leaves are covered with black coating and ultimately photosynthetic activity is 

hampered. Lint quality is also affected due to deposition of sooty mould on open bolls. 

BOLLWORM COMPLEX : 

The term bollworm is not particularly useful. Whilst it clumps together a group of insects 

that are members of the order Lepidoptera, that is really where the similarity becomes thin 

- except, of course, that the caterpillars - the worms - do bore into the bolls of cotton plants. 

But they also strip the leaves, destroy buds and bore into the stems. Perhaps we should 

call them cotton caterpillars. 

Most species of bollworm (other than Helicoverpa) have spread all round the world. This 

is because they are carried with the product they infest, both in the lint and the seed - and 

by the accidents that confound the most stringent of quarantine procedures. The implication 

is that even if a given species is not present now it could be one day. 

Pink bollworm, Pectinophora gossypiella (Saunders) : The larvae do the damage. Initial 

instars are white bearing pinkish ting, which subsequently change in pink color. Larvae are 

found inside flower buds and the bolls of cotton The pest remains active in cotton ecosystem 

during July to October-November and passes the winter season hibernating in the 

cotton seeds If five percent damaged fruiting bodies are found effected the pest is considered 

in serious proportions. Larval stage damages the buds, flower and bolls. Soon after emergence, 

the larvae enter the flower buds, flowers and the bolls. Entry hole is closed down and larvae 

continue its feeding in side the bolls. The attacked bolls fall off prematurely and the others, 

which remain on plant, don’t contain good quality lint and the last of the season due to its 

damage double seeds are formed. 

Spotted bollworm (Earias vittella Fab. & Earias insulana Boisd) : The pest remains 

active throughout the year on one or the other host. But in cotton ecosystem, damage is 

done during August to October Pest is considered to be serious if the population during 

vegetative stage damage one percent shoots. During reproductive stage if 5 percent fruiting 

73

odies are damaged, the pest has reached to economic threshold. In the vegetative stage 

larval bore into the growing shoots and the affected shoots droop down. Later on, during the 

reproductive stage, larvae borer in to the flower buds, flowers and green bolls consequently 

shedding of the fruiting bodies takes place. The attacked bolls are tunneled and blocked 

with excreta. The infested bolls open prematurely and the lint is spoiled resulting in lower 

market value 

American bollworm (Helicoverpa armigera Hubner) : It is a highly polyphagous insect 

pest. Helicoverpa’s range extends over four continents, it is polyphagous, consuming cotton, 

tomatoes and other vegetables, coarse grains (maize, sorghum and pearl millet), all grain 

legumes, and other crops.The crops it attacks are essential for food security or of high 

commercial value, and the larvae feed on and spoil or destroy the ripening fruit and seed 

pods of the crops it attacks, which are often the plant parts that farmers want to harvest. 

The newly hatched larva initiates feeding on the buds, squares, flowers and bolls of the 

cotton crop. The larvae make a circular hole on the fruiting bodies and as the larvae grow up 

half of the larval body remain outside and release the facial material outside. Fully damaged 

fruiting body shed down. Fully ripen bolls are not damaged by the American bollworm. During 

early season the larvae may also be noticed feeding on the succulent leaves. 


Dhawan, A.K., 2000 Cotton pest scenario in India : current status of insecticides and future 

perspectives. Agrolook 1 (1) : 9-26. 

Gupta, G. P. 1999. Use of safer chemicals in cotton IPM system – a review. J. Cotton Res. 

Dev. 13 (1) : 56-62. 

Hargreaves, H. 1984. List of Recorded Cotton Insects of World. Commonwealth Institute of 

Entomology. London, pp. 50. 

74


LOSSES DUE TO INSECT-PESTS IN PADDY 

Lakhi Ram 


CCS Haryana Agricultural university, Hisar-125 004 

There are more than 100 insect species recorded as feeding on rice plant. About 20 of 

them reached the status of pests causing economic losses under farmers’ situation. Among 

them stem borer, planthopper, leafhopper, leaf folder, gall midge, rice hispa, gundi bug, case 

worm & armyworms are the most important. Different stages of insects injure rice plants. 

Injury from feeding leads to damage symptoms on plant parts. The correct and rapid diagnosis 

is of greatest importance as required by the farmers, agricultural planning staff, insurance 

personnels, valuers of yield and yield losses. 

2. Diagnostic Symptoms 

Field diagnosis of injury caused by all insects, (except planthoppers, grain bugs) can 

clearly be recognized by above ground symptoms at different stages of crop growth. These 

symptoms are described here in brief. 

2.1 Stem borer (Scirpophaga incertulas Walker) 

The stem borer attacks throughout the growth period. In the vegetative stage, the larva 

bores into and feeds inside the stem, and as a result the central leaf whorl does not unfold, 

turns brownish and dries out resulting in the formation of dead hearts. In the reproductive 

stage, the damage results in the formation of whitish, chaffy and erect panicles known as 

white ears. 

2.2 Brown planthopper (Nilaparvata lugens Stal.) 

Both adults and nymphs suck the sap from the base of the stem, resulting in yellowing 

and drying of the plants. At early stages of attack, round, yellowish patches appear which 

soon turn brownish due to drying up of the plants. The patches of infestation spreads in 

concentric circles within the field and in severe cases the affected field gives a burnt 

appearance known as hopper burn. 

2.3 Whitebacked planthopper (Sogatella furcifera (Horvath) 

Both nymphs and adults suck the plant sap from phloem and causes drying up of plants. 

Unlike brown plant planthopper (BPH), it does not cause sudden and severe hopper burn. 

2.4 Leaf folder (Cnaphalocrocis medinalis Guenee) 

The larva folds the leaves with the help of silken threads secreted from salivary glands, 

remains inside and feed on the chlorophyll content of the leaves, leaving only the lower 

epidermis which make the leaves white and papery. Gradually, the leaves dry up and turn 

brown. Under heavy infestation, the field presents a scorched appearance. 

2.5 Gall midge (Orseolia oryzae Wood Mason) 

The maggot enters the young rice plant and starts feeding on growing portion. As a 

result, the meristematic tissues grow and turn into a pale green tubular structure called 

Silver Shoot. The damaged tiller does not bear panicle and the crop under severe infestation 

is stunted. 

75

2.6 Rice hispa (Dicladispa armigera Oliver) 

Earlier considered to be a sporadic and minor pest has attained the status of a regular 

and major pest in north-eastern, eastern and central region of India. Both adults and grubs 

damage the crop. The adult scrap the chlorophyll content both on the upper and lower side 

of leaves. The grubs mine in between two epidermal layers and feed on the chlorophyll 

content. In severe infestations, the crop gets dried with whitish appearance without any 

green color. 

2.7 Green leafhopper (Nephotettix virescens Dist.) 

The leafhoppers feed on the leaf and suck the sap from phloem as well as xylem. But 

they don’t cause hopper burn. The damage to the rice plant by this kind of injury is of less 

importance as plant does not loose much of its vigor. 

2.8 Rice earhead /Gundhi bug (Leptocorisa acuta Thunb.) 

The nymphs and adults feed on developing/partial milky grains causing brown spots, 

partially filled and chaffy grains. The nymphs as well as adults emit a characteristic effective 

odour in infested fields, which can be very easily recognized as a signal of presence of gudhi 

bug in rice fields. 

2.9 Swarming caterpillar (Spodoptera spp.) 

This is an occasional pest but can cause serious damage in the dry season. When high 

population occurs, the army of swarming caterpillar march in the field and feed on leaves by 

cutting of leaf tips, leaf margins, leaves and plant at the base. 

2.10 Rice case worm (Nymphula depunctalis Guenee) 

It is commonly found in low lands with poor drainage and flooded field. The attack is 

usually patchy and not continuous. The larva cuts the leaves into small bits and makes 

them into cases of approximately its own body size. The larva remains inside the case and 

feeds on leaves by scraping the chlorophyll content. As a result, the plant growth and vigor 

are seriously affected. If the leaves are distrubed the cases along with larva fall on water 

surface. 

3. ASSESSMENT OF LOSSES 

3.1 Estimates of insect- caused yield losses 

Several studies have reported rice yield losses due to insects in Asia. Cramer (1967) 

reported that yield lost to all insects in tropical rice was 34%. Pathak and Dhaliwal (1981) 

reported 35-44% and several other studies report losses of similar magnitude. 

Table 1 shows the estimates of losses in recent period as compiled in country studies. 

Although different methods were used to derive the estimates, with one exception of Indonesia 

the losses are of similar magnitude. Stem borer damage reported in all location range from 

1 to 110 kg/ha across study location. Rice leaf folder losses ranged from 9 to 44 kg/ ha in 

six of seven locations. Brown planthopper losses were also reported in six of seven locations 

with damage ranging from 7 to 34 kg/ha. 

76

DIAGNOSTIC SYMPTOMS OF INSECT-PESTS' DAMAGE IN PADDY 

Rice leaf folder 

Brown planthopper 

Rice stem borer 

Rice gundhi bug

Table 1. Estimated average rice production losses (kg/ha) caused by main insects 

Region SB RLF BPH GLH Earhead bug GM RH 

East India 35 9 7 15 3 8 NA 

West Bengal 1 15 25 NA NA NA 1 

Southern India 32 44 23 19 35 25 NA 

Bangladesh 38 11 NA NA 40 NA 41 

Indonesia 346 NA 25 NA 28 NA NA 

Thailand 1 9 21 12 NA NA NA 

Nepal 110 42 34 41 20 NA 89 

Source : Ramasamy and Jatileksono, 1996 


Bautista, R.C. , Heinrichs, E.A, Rejesus, RS. 1984. Economic injury levels for the rice leaf 

folder Cnaphalocrocis medinalis (Lepidoptera: Pyralidae). Insect infestation and artificial 

leaf removal. Environ. Entomol. 13 : 439-443. 

Cramer, H.H. 1967. Plant Protection and World Crop Production. Pflanzenschutz Nachrichren 

Bayer 20. 

Heinrichs, E.A.,Viajante, V.D. 1987. Yield loss in rice caused by the caseworm Nymphula 

depunctalis Guenee (Lepidoptera: Pyralidae). J Plant Prot.Tropics 4 : 15-26. 

International Rice Research Institute (IRRI) 1990. Crop Loss Assessment in Rice. IRRI, Los 

Banos, Philippines. 

Litsinger, J.A. 1991. Crop Loss Assessment in Rice. In : E.A.Heinrichs and T.A. Miller 

(eds.). Rice Insects : Management Strategies. Springer, New York, PP.1-65. 

Ramasamy, C. and Jatileksono, T. 1996. Intercountry comparision of insects and disease 

losses . In : Evenson, R.E., Herdt, R.W and Hossain, M. (eds.) . Rice Research in Asia 

- Progress and Priorities .CAB International and IRRI, pp. 305-316. 

Rama Parsad, A.S., Krishanaih, N.V. and Pasalu, I.C. 2004. Estimation of yield loss due to 

measure insect pest interaction in rice. Indian J. Pl. Prot. 32 (2) : 26-28. 

Singh, J. and Dhaliwal, G.S. 1994. Insect pest management in rice : A perspective, In : 

Dhaliwal, G.S. and Arora, R. (eds.). Trends in Agricultural Insects Pest Management, 

Commonwealth Publishers, New Delhi, India. pp. 56-112. 

Suenaga, H. and Nomura, K. 1970. Host : Oryza Sativa (rice), Organisms : Nilaparvata 

lugens ( brown planthopper). In : L.Chiarappa (ed.). Crop Loss Assessment Method. 

FAO Manual on Evaluation and Prevention of Losses by Pest, Diseases and Weeds. 

1971. FAO and Commonwealth Agric. Bur. 

77


DUE TO INSECT-PESTS IN PULSES 

Roshan Lal 



India is a major pulse growing country in the world, sharing 35-36 per cent area and 27- 

28 per cent of production of these crops. It is producing 12-14 million tones of pulses from 

22-24 million ha of land. The commonly grown pulse crops in India are chickpea (Cicer 

arietinum), pigeonpea (Cajanus cajan), mungbean (Vigna radiata), urdbean (Vigna mungo), 

horsegram (Macrotyloma biflorus), mothbean (Vigna aconitifolia), lathyrus (Lathyrus sativus), 

lentil (Lens culinaris), cowpea (Vigna unguiculata), drybean (Phaseolus vulgaris) and peas 

(Pisum sativum). A few minor pulses such as ricebean (Vigna umbellota) and fababean 

(Vicia faba) are grown in specific areas only. Pulses are rich sources of protein to vegetarians 

and have an inherent capacity to fix large amounts of atmospheric nitrogen in symbiotic 

association with Rhizobium.Cultivation of chickpea and pigeonpea in India takes place under 

diverse agroecological nitches such as rainfed/ irrigated, mixed/ monocrop, early/late maturity 

group, low /high input conditions, traditional/progressive farming etc., posing a highly variable 

spectrum of pest problems. The insect pest spectra that infest these pulse crope include 

more than 50 species on chickpea and 300 species on pigeonpea. 

Chickpea 

Several insect pests have been noticed to attack the chickpea crop at different crop 

growth stages but gram pod borer, Helicoverpa armigera is the single most important pest of 

legumes, cotton, cereals, vegetables and fruit crops in Asia, Africa, Australia and the 

Mediterranean Europe. Other insect pests which cause losses to the chickpea crop are 

termites, Odontotermes obesus (Rambur) and Microtermes Obesi Holm, cutworms, Agrotis 

ypsilon (Huf.) and A. flammatra Schiffer-Mueller, semilooper, Autographa nigrisigna (Wlk.), 

bean aphid, Aphis craccivora Koch and tobacco caterpillar, Spodoptera exigua. 

The insect pests that occur at vegetative and-flowering stages of chickpea and pigeonpea 

do not usually cause economic loss. But the infestation that occurs at reproductive stage, 

mainly on pods and seeds can significantly reduce the crop yields as there is not much time 

left for plant to compensate. The pod borer complex of chickpea and pigeonpea varies 

according to the crop maturity and agro-ecological nitches. 

Pigeonpea : The insect-pests infesting pigeonpea pods and seeds are lepidopterans, 

dipteran, coleopterans and hymenopterans. In addition to pod borers, hemipteran bugs 

(Clavigralla spp.) also sometime cause considerable economic losses to pigeonpea. 

Among the pod infesting insect pests of pigeonpea (Table 1), the gram pod 

borer,Helicoverpa armigera (Hubner) and the podfly, Melanagromyza obtusa Malloch are of 

major importance on medium and late maturing pigeonpea whereas the gram pod borer, H. 

armigera, the spotted caterpillar, Maruca testullis, the leaf tier, Eucosoma (Cydia) critica 

and the pod fly, M. obtusa are major insect species of early maturing pigeonpea. 

Amongst medium and late pigeonpea gram pod borer is a predominant borer of south India 

and podfly a major borer species of central and north India. Also, the podfly, M. obtusa is 

comparatively more damaging on late maturing varieties than on early maturing varieties. The pod 

weevil, Apion clavipes is important in north eastern coastal regions of India, including Bihar. 

78

Table 1. Pod Borer Complex infesting pigeonpea 

Group Common name Scientific Name Status Distribution 

Lepidoptera Gram Pod borer Helicoverpa armigera Major All States 

Spotted Pod borer Maruca testulatis G. Major Central & North India 

Plume Moth Exelastis atomosa W. Minor All States 

Blue Lampides boeticus L. Minor — do — 

Butter Fly Catochrysops strabo F. Minor — do — 

Pod borer Etiella zinckenella T. Major — do — 

Diptera Pod borer Melanagromyza obtusa Major Central & North India 

Colepotera Bruchid borer Callosobruchus maculatus F. Major All States 

C. analis F. Minor — do — 

Pod weevil C. chinensis L. Major — do — 

Apion clavipes G. Major Central & North India 

Hymenoptera Pod wasp Tanaostigmodes cajaninae L. Major All States 

Hemiptera Pod bug Clavigralla gibbosa S, Major — do — 

Pod bug Riptortus spp. Major — do — 

Green bug Nezara viridula Major — do — 

CROP LOSS ASSESSMENT 

Chickpea 

The loss in yield caused by H. armigera has been reported to be 40% to 100% in Madhya 

Pradesh and 30-50% in Punjab. “Large scale extensive field surveys conducted by IIPR 

entomologists during 1979-81in 38 districts of Uttar Pradesh showed mean pod damage due 

to H. armigera from 3.1 to 32.9 per cent, with an overall mean of 14.6%pod damage for the 

whole state (Lal et al. 1985). Similar extensive field surveys conducted by ICRISAT in different 

states of India during 1977-82 revealed mean pod damage of 2.4-15.1 per cent, with a national 

mean of 7.8% (Reed et al., 1987). 

Pigeonpea 

ICRISAT total mean pod damage due to borer complex from 35.8 to 49.0 per cent. They 

also observed that H. armigera was relatively more severe (29.7% pod damage) in north 

west zone where early maturing pigeonpea varieties are grown. In north India, the 

Melanagromyza obtusa appeared to be the dominant pest on late varieties (20.8% pod 

damage). Where as, in central India, the lepidopteran borers (mainly, H. armigera) and the 

pod fly, M. obtusa, both were serious and caused 46.6% pod damage. However, H. armigera 

was key pest and caused 36.4% pod damage (Lateef and Reed 1981 and Sachan 1990). 

Similar surveys were conducted by IIPR entomologists in Uttar Pradesh during 1978-84 

and recorded 24.6 to 48.6 per cent grain damage in the state due to pod borer complex, with 

a mean of 35 per cent grain damage (Table 2). In Uttar Pradesh, the podfly, M. obtusa was 

the key pest on late maturing varieties which occupy 90 per cent of the pigeonpea area and 

caused maximum loss (24.6% grain damage) to the crop (Sachan 1990 and Lal et al. 1992). 

79

Tabel 2. Grain damage caused by lepidopteran borers and pod fly in determinate 

and indeterminate late maturing pigeonpea cultivars at the Indian Institute 

of Pulses Research farm at Kanpur India 1980-83. 

Plant type Cultivar % grain damaged 

1980-81 1981-82 1982-83 

Pod fly Lep. borer Pod fly Lep. borer Pod fly Lep. borer 

Determinate Allahabad local 26.3 8.2 27.8 10.2 27.5 14.1 

Indeterminate Kanpur 39.8 3.3 38.3 5.2 36.9 9.6 

BLACK GRAM, VIGNA MUNGO (L.) HEPPER 

Over 64 species of insect pests have been found associated with the crops of Vigna 

group (Lal, 1985). Of these, Caliothrips indicus, Megalurothrips dista/is (Karny); leaf hopper, 

Empoasca ke ri Pruthi; whitefly, Bemisia tabaci Gennadius; hairy cater pillars, S. obliqua 

(Wlk.) and A. moorei Butl.; galerucid beetle, Madurasia obscurella, tobacco caterpillar, 

Spodoptera litura F.; pod borers, L. boeticus L., H. armigera Hubner, M testulalis Geyer and 

Grapholita critica Meyr are the common pests. Late sowing and dry spell experienced an 

outbreak of Maruca testulalis which resulted in almost 100% loss of flower buds and pods in 

Karnataka (Giraddi et al., 2000). 

Yellow Mosaic Virus 

The accurrence of yellaw masaic virus (YMV) is one of the most severe biotic stresses 

in many kharif pulse crops. The viral disease is transmitted by the whitefly, B. tabaci, and 

the yield of the plants is affected drastically. 

MUNGBEAN, VIGNA RADIATA (L.) WILCZEK 

On mungbean, at one week intervals from one week after germination until harvest, some 

31 species of insect pests were recorded, 20 of which were the regular visitors and 11 were 

the sporadic ones. The crops were mainly infested by B. tabaci, E. kerri, A. craccivora, 0. 

phaseoli, N. viridula and Phytomyza horticola. Out of these B. tabaci was the most important 

(Dar et al., 2002). 

Larvae of Rivellia sp. were found infesting the nodules of mungbean, urdbean, cowpea, 

red gram and groundnut. Upto 98 per cent nodule damage occurred on crops sown in kharif 

season in Karnataka. The platysomid completely emptied the nodules and plant growth was 

adversely effected. Damaged nodules showed a single characteristic minute entry and exit 

hole. Infested nodules were shriveled and discoloured. Root and shoot length, total dry 

matter, nodule dry weight and grain yield were reduced. Ostrinia furnacalis (Guenee) to 

mungbean, V. radiata (L.) Wilzeck, most of the larval feeding is confined inside stems, but 

some larvae are also found in the roots and pods. The higher the diameter and longer the 

internodes, the greater was the damage. 

Lentil : Lentil is an important pulse crop grown in Asia (India, Jordan, Lebanon and 

Turkey). Among the biotic constraints, insect pests play a major role. About 36 insect pests 

have been reported to infest lentil under field and storage conditions, of which 21 have been 

reported from India. The insect-pests feeding on lentil under field conditions include aphids, 

bud weevils, cutworms, leaf weevils, lygus bugs, pod borers, stink bugs and thrips. 

Diagnostic symptoms 

Gram pod borer : The freshly emerged larvae of Helicoverpa armigera initially feed on 

the tender leaves by nibbling on chickpea, pigeonpea and few other legumes, causing 

80

DIAGNOSTIC SYMPTOMS OF INSECT-PESTS' DAMAGE IN PULSES 

Blue butterfly 

Pod borer in chickpea 

Cutworm 

Clavigralla gibbosa 

on pigeonpea

extensive damage. Damage in cotton and pigeonpea is mostly to flowers and flower buds 

and later on shifted to bolls and pods of the crop. Young chickpea seedlings may be destroyed 

completely, particularly under tropical conditions in Southern India. At pod stage, the larvae 

make hole into the pod and feed inside the pod. Normally the larvae are seen feeding in pod 

on developing seeds by intruding anterior half inside the pod and rest posterior hanging 

outside. 

Thrips : Several species of thrips viz., Caliothrips indicus, Megalurothrips distalis, Thrips 

augusticeps, Thrips tabaci damage grain legumes including mungbean, urd bean and lentil. 

Most of the thrips prefer flowers but in the absence of flowers, they also feed on foliage. 

When the population of thrips are high, the growing points of the plants may blacken and 

wither. Feeding by thrips on young leaves results in silvery streaks on the opened leaves 

and distortion or curling of leaves. When infestation is severe, the leaf area is reduced, 

which indirectly affects photosynthesis and grain yield. 

Spodoptera exigua : It is a serious pest of beet, broccoli, cabbage, cauliflower, celery, 

chickpea and corn etc. The young larvae initially feed gregariously on chickpea foliage. As 

the larvae mature, they become solitary and continue to eat, producing large, irregular holes 

in the foliage. But it has not been reported as a serious pest on pods. 

Black aphid : Both nymphs and adults suck the plant sap from the tender leaves, 

stems and pods and colonize mostly on the young leaves and growing points which become 

deformed. Yield can be drastically reduced and if infestation are early and severe, plants 

can be killed. Infestation during the bloom and early pod stages reduce yield and crop 

quality by removing plant sap, impairing pod appearance and reducing seed fill and by the 

presence of aphid honey dew upon which sooty mold grows. 

Black cutworm : The black cutworm feeds on chickpea, lentil, pea, potato and other 

crops in northern India. The larvae feed on leaves, stems and roots of many field crops upto 

10 per cent plant damage has been recorded at 40 days after crop emergence in chickpea. 

The larvae come out of their hiding places at night and damage the plants only under the 

cover of deepness. Generally, this pest attacks the chickpea crop in two stages of its growth. 

In the seedling stage, the stem is generally cut at an average height of 5 cm from the soil 

surface. They consume only a little of the stem and then nibble and move to attack others. 

During later stage of growth, the shoots are damaged by cutting them at an average height 

of 24 cm from the soil surface where the stem is soft. 

Bruchids : Members of the family bruchidae have been reported to destroy the seeds of 

leguminous plants. Female of Callosobruchus maculates and C. chinensis lay eggs, which 

are visible to the naked eye on the seeds. Bruchids tend to lay eggs singly on a given host, 

but if all the seeds are occupied, the female starts laying eggs on already egg-laden seeds. 

The neonate larva bores into the seed beneath the oviposition site and completes its 

development within single seed. Damaged seeds are riddled with adult emergence holes 

and become unfit for human or animal consumption. 

Green stink bug : The green stink bug feeds on many weeds and several important 

agricultural crops including barley, lentil, pigeonpea, cowpea, fababean, mungbean, tomato 

and wheat etc. The nymphs and adults of Nezara viridula suck the sap from leaves, stems 

and pods, resulting in malformation or drying up of the pods. In lentil, they suck sap from 

shoots and pods. The bugs cause varying degrees of damage from the seedling stage, when 

the young growing tips of plants dry up, until crop harvest. They are especially damaging 

during the reproductive phase, when they feed on the pods. 

81

Leaf weevil : Both adults and larvae of Sitona crinitus damage the lentil crop, but the 

larvae are more damaging. The adult weevils feed on foliage making semicircular notches in 

the leaf edges early in the season. The adult feeding normally does not affect yields unless 

population are very high. Usually plants can quickly compensate for foliar damage. The 

larvae are serious pest on nitrogen fixing nodules of lentil. 

Leafminers : In addition to chickpea, Liriomyza cicerina has been reported to feed on 

Alliums spp., beet, Brassica spp., capsicum, faba bean, groundnut, lentil, pea and several 

other crops. Chromatamyia horticola is a polyphagous pest and feed on alfalfa, chickpea, 

faba bean, field pea and mung bean etc. L. cicerina females puncture the upper surface of 

chickpea leaflets with their ovipositors and feed on the exudates, which results in a stippled 

pattern on the leaflets. In some feeding punctures, eggs are inserted just under the epidermis. 

When the eggs hatch, leafminer larvae feed on the leaf mesophyll tissue, forming a serpentine 

mine that later becomes a blotch. The mining activity of the larvae reduces the photosynthetic 

capacity of the plant and under heavy infestation, may cause dessication and premature 

leaf fall. Leaf miner damage at times may destroy young seedlings or result in leaf drop and 

reduction in crop yield. Upto 30% yield losses have been reported in chickpea in Syria. 

Lima bean pod broer : Lima bean pod borer feeds on several leguminous crops 

especially cowpea, fieldpea, greengram, horse gram, lentil, lima bean, pigeonpea and 

sunhemp. The presence of a hole on the pod surface, dry light coloured frass and webbing in 

the pod are indications of infestation. Individual seeds have holes and internal portions are 

gutted. The pods are partially or completely consumed inside. Externally the pods have a 

shrunken appearance and small surface punctures. Larvae generally feed on maturing pods. 

Lygus bugs : Lygus lineolaris and L. hesperus are polyphagous pest on several crops 

and weeds. Economic losses have been recorded in alfalfa, cotton, lentil, lima bean, snap 

bean, soybean and tomato. Lygus bugs puncture the tissue and feed on immature reproductive 

structures, causing chalky spot syndrome-on lentil seeds, which increases the prevalence 

of shriveled, unfilled pods and seed abortion. Incidence of growing point injuries by Lygus 

spp. is a serious problem on cauliflower in Sweeden. 

Whitefly : Bemisia tabaci pierces stylet in plant tissue and suck sap from phloem 

tissue. Plant becomes yellow week by excessive drainage of sap and leaves are deformed. 

They produce large amount of sugar excreta (honey dew) on which black sooty mold grows 

which interfere the photosynthesis. It also acts as a vector of Gemini virus especially in 

cucurbitaceae, leguminaceae, malvaceae, solanaceae & Euphorbiaceae families. 

Termite : Termites are polyphagous insect pests of crops and often a limiting factor in 

their successful cultivation. Termite damage plants wilt, dry up and can be easily pulled up. 

Termite damage the crops right from their sowing till harvest. Damage due to termites may 

lead to poor germination in crops. However, due to their incidence in grown up plants, the 

yields are reduced drastically. 


Chen, W., Sharma, H.C. and Muehlbauer, F.J. 2010. Compendium of chickpea and lentil diseases 

and pests. The American Phytopathological Society, Minnesota (USA). pp. 99-125. 

Lal, R. and Rohilla, H.R. 2007. Insect pests of pulses and their management. Natnl. J. Pl. 

Improv. 9 (2) : 67-81. 

Sachan, J.N. and Lal, S.S. 1997. Integrated pest management of pod borer complex of chickpea 

and pigeonpea in India. In : Recent Advances in Pulses Research. (A.N. Asthana and Masood 

Ali Eds.). Indian Society of Pulses Research and Development, Kanpur. pp. 349-376. 

82

DIAGNOSIS AND CROP LOSS ASSESSMENT FOR 

ECONOMICALLY IMPORTANT PLANT DISEASES 

S. K. Gandhi 

Department of Plant Pathology 


It is a well known fact that diseases caused by fungi, bacteria and viruses can lead to 

high losses of crops. When the epidemic is spread over large areas and if all plants are 

more or less susceptible to the devastating pathogens, there can be complete losses of 

crops. Further diseases can result not only in quantitative yield loss but also in qualitative 

losses due to lower food quality and to decreased potential for storage and mycotoxin 

contamination. 

Impact of Plant Diseases : There are several examples of disease epidemics that have 

caused remarkable food deficiencies or depletion of a complete crop out of a particular area. 

The late blight of potato caused by Phytophthora infestans has led to periods of starvation 

by epidemic spread in Ireland during 1845 and 1846. The outbreak of coffee rust caused by 

Hamileia vastatrix in early 1870s led to a depletion of coffee from India and Sri Lanka which 

then became substituted by tea. In the 1930s the entire banana industry in Central and 

South America was threatened with extinction by Sigatoka disease (Mycospharella musicola). 

In France, between 1878 and 1882, the wine industry was threatened due to the introduction 

of downy mildew from U.S.A. In India, the 1942 Bengal famine was perhaps largely due to 

Helminthosporium disease of rice. In 1946-47, the wheat rust epidemic was responsible for 

food shortage in India. During 1969-70 there occurred one of the most devastating epidemics 

in USA due to the southern corn leaf blight, when cytoplasmic male sterility used for the 

production of hybrid seed maize was introduced into almost all maize varieties. Another 

instance of serious loss by a disease is due to red rot of sugarcane which reached its peak 

in 1938-39 in the white sugar belt of India. In the badly affected areas, most of the mills 

could crush only 33 per cent of their normal quantity. Likewise there are several examples 

of catastrophic diseases which had disastrous consequences for man and made a drastic 

impact on his affairs. These examples amply prove that diseases can entirely change the 

course of history and economy of a country. The advances made in food production due to 

green revolution can be lost if proper attention is not given to plant diseases and other 

pests. 

Diagnosis of Plant Diseases : On the basis of examination of the typical symptoms 

present in a diseased plant, it becomes fairly easy to diagnose the diseases and also the 

pathogen involved. In most cases, however, a detailed examination of the symptoms and an 

inquiry into characteristics beyond the obvious symptoms are necessary for a correct 

diagnosis. 

A. Symptoms due to character and appearance of the visible pathogen or its structures : 

A parasite is present in all the parasitic diseases but in most cases the growing vegetative 

portion is within the host tissues and is, therefore, invisible. In some cases, almost the 

entire body of the parasite, including both vegetative and reproductive portions, is external 

to the host and is, then, readily seen, partly on account of its mass. In a number of diseases 

the structure of the pathogen constitutes the most prominent symptom of the disease. Several 

of such symptoms are : 

83

a) Mildew : In mildews the pathogen is seen as a growth on the surface of the host. 

They appear as white, grey, brownish, purplish patches of varying size on leaves, 

herbaceous stems, or fruits. In downy mildews the superficial growth is a tangled 

cottony or downy layer, while in the powdery mildews enormous numbers of spores 

are formed on superficial growth of the fungus giving a dusty or powdery appearance. 

b) Rusts : The rusts appear as relatively small pustules of spores, usually breaking 

through the host epoidermis. The pustules may be either be dusty or compact, and 

red, brown, yellow or black in colour. 

c) Smuts : The word smut means a sooty or charcoal-like powder. The affected parts 

of the plant show a black or purplish-black dusty mass., These symptoms usually 

appear on floral organs, particularly the ovulary and the pustules are usually 

considerably larger than those of the rusts. Smut symptoms may also be found on 

stem and leaves. 

d) White blisters : On leaves of cruciferous and other plants there may be found 

numerous white blister-like pustules which break open and expost powdery masses 

of spores. Such diseases have been commonly known as white rusts. Since there 

is nothing common between them and the true rusts they may be more appropriately 

called white blisters. 

e) Scab : The term scab refers to a roughened or crust-like lesion or to a freckled 

appearance of the diseased organ,. In some diseases of this type the parasite 

appears at a certain stage, in others it is never seen. 

f) Bunt : A disease in which the grain contents are replaced by odorous smut spores. 

g) Mould : A sooty or black coating on foliage or on fruits formed by dark hyphae of the 

fungi. Sometimes it is due to green coloured hyphae of fungi, then it is called green 

mould. 

h) Exudations : In several bacterial diseases, such as in bacterial blight of paddy and 

fire blight of pome-fruits, masses of bacteria ooze out to surface of the affected 

organ where they may be seen as drops of various size or as thin smear over the 

surface. 

i) Ergot : Appearance of creamy droplets of a sticky liquid exuding from young florets 

of infected heads which are soon replaced by hard sclerotia of the fungus e.g. ergot 

of pearl millet. 

B) Symptoms due to some effect on, or change in, the host plant : 

As a result of disease there may be marked change in the form, size colour, texture, or 

habit of the plant or some of its organs. Such changes are ususlly readily observed and 

often constitute the most prominent symptom of the diseases. In most diseases these 

changes are brought about through the presence and activity or life processes of some 

foreign living organism and reaction of the host tissues to such activity,. The pathogen may 

be found within the affected tissues, or upon the surface, or in some cases it may develop 

certain structures internally and others externally. 

a) Colour changes : The green pigment may disappear entirely and its place may be 

taken by a yellow pigment. When this yellowing is due to lack of light the condition 

is known as etiolation. A similar condition may be brought about by the influence of 

low temperature, lack of iron, excess of lime, presence of certain virus diseases or 

84

DIAGNOSTIC SYMPTOMS OF ECONOMICALLY IMPORTANT PLANT DISEASES 

Wheat – yellow rust Wheat – stem rust Wheat – loose smut Ergot of Bajra 

Downy mildew of bajra Rice blast Leaf curl of chilli 

Late blight on 

Potato Tubers 

Potato late blight 

Tomato early blight Tomato late blight 

Alternaria leaf spot 

of crucifer 

Early in season 

Same disease affects 

tomato, potato, eggplant, 

pepper 

Look for target like spots 

Early Blight of Potato and Tomato 

Alternaria solani (Fungus)

from the disturbances caused by fungal and bacterial diseases. In these cases the 

yellowing is known as chlorosis. Uneven development of chlorophyll producing light 

green patches with dark green areas is known as mosaic, the most common symptom 

in viral diseases. 

b) Over growth or Hypertrophy : In some diseases there is abnormal increase in size 

of one or more organs of plant or plant parts. This is usually due to the stimulation of 

host tissues to excessive growth due to hyperplasia (increase in number of cell) or 

hypertrophy (increase in size of cell) or both. Over growths are of various forms in 

different diseases and are known by different names. 

i) Gall : Abnormal development of infected plant parts may be due to hypertrophy 

or hyperplasia. It may be more or less globosely, elongated or irregular e.g. 

Crown gall, Club root of Crucifers. 

ii) Witches broom : Numerous slender branches arise from a limited region in 

close clusters just like a broom e.g. Witches broom of Potato. 

iii) Curling : It refers to the abnormal bending or rolling or folding of plant organs 

particularly in leaf due to localized out growth of host tissues. 

iv) Enations : Over growth or tumour like structure appear on the surface of leaf 

along the veins. 

v) Phyllody : Floral parts develop into leaf like structures. 

vi) Vein clearing : In this case veins become light green and clearer than the 

surrounding interveinal area. 

vii) Vein banding : In this case tissues close to the veins become darker than the 

surrounding interveinal tissue. 

c) Atrophy or Dwarfing or Stunting : It is abnormal development of most of the plant 

parts causing reduction in plant height, leaf size and other organs, most common in viral 

diseases. 

d) Necrosis : These symptoms that results from death of cell, tissue or organ due to parasitic 

activity of the organism. 

i) Blight : Rapid killing or sudden death of plant or plant parts. It gives burnt 

appearance. 

ii) Blotch : Appearance of large, irregular lesions on leaves, shoots and stems. 

iii) Canker : Necrotic lesions often sunken in the cortical tissues of stem, leaves or 

twigs. 

iv) Anthracnose : Appearance of black sunken lesions on leaf, stem and fruit and 

pathogen produce fruiting bodies i.e. acervuli on infected tissues. 

v) Die back : Dying of plant organs especially the branches from top to downwards., 

vi) Damping off : Death of the seedlings near the soil level as a result of which the 

seedling topples down on the ground. 

vii) Rot : The affected tissue die, decompost and turn brown It takes place due to the 

production of cell wall degrading enzymes by the pathogen. 

85

viii) Lesion : It refers to the distinct and localized spot on the host tissues. 

ix) Spots : Usually defined as circular or oval shape with central necrotic areas 

surrounded by variously coloured zones, some times they are restricted by veins. 

x) Shot hole : Circular hole in leaves resulting from the drooping out or detaching of 

the central necrotic areas. 

xi) Streak or stripe : Development of minute linear lesions known as streak. 

Enlargement of streaks into variable length and breadth are known as stripes. 

xii) Wilt : The leaves and other succulent parts loose their turgidity and droop. 

Economically Important Plant Diseases : 

The disease scenario in different regions may vary with the changes in weather and soil 

conditions. In some cases major pathogen from one region are not present in other areas 

owing to adaptability of the pathogens to varied conditions. The major crop diseases and 

losses they may cause are summarized here. 

Amongst cereals, wheat and barley are highly prone to infection by rusts and smut. 

Three rusts i.e. Black rust or stem rust, brown rust or leaf rust and yellow rust or stripe 

occur on leaves, leaf sheath, stem, glumes and earheads. Yield losses depend on the stage 

at which plants are affected and prevalence of congenial environmental conditions. Loose 

smut affects the ear heads, which are transformed into black powdery mass. In recent years 

flag smut is also causing losses in yield in some areas. Karnal bunt affects the grain quality 

adversely. Powdery mildew causes premature drying of leaves. In barley, stripe disease 

attacks the foliage which later on dry and give shredded look. 

In rice, blast is the most damaging disease followed by sheath blight. Bacterial blight, 

Bakanae and false smut are reported to cause economic losses. In rice production, the loss 

potential of pathogen exceeds 20% in Europe, North America and East Asia where productivity 

is high. The infection pressure is low in other regions. 

In pearl millet, downy mildew, smut and ergot diseases cause major economic losses. 

Various types of smuts in sorghum adversely affect grain yield while leaf spot diseases 

reduce the fodder quality. Diseases in maize production are of lower economic importance 

than weeds or pests. However, foot rot, stalk rot and head smut cause considerable losses 

when not controlled. 

Wilt, root rot, angular leaf spot and leaf curl are the most important yield-limiting factors 

in cotton. Being a major cash crop for developing countries and in general, crop protection is 

intensive. Red rot in sugarcane is a major disease adversely affecting both yield and quality 

of the crop. Other diseases causing economic losses are ratoon stunting grassy shoot and 

smut. 

In oilseed crop of rapeseed and mustard, white rust, Alternaria blight, downy mildew and 

white stem rot are the principal diseases hampering the production. Amongst pulses; 

Ascochyta blight and wilt in chickpea; wilt and Phytophthora blight in pigeonpea; yellow 

mosaic view in mungbean are the major disease problems. 

Late blight caused by Phytophthora infestans is considered to be the major yield limiting 

disease in potato. Other diseases of economic importance include black scurf, soft rot and 

few viral diseases. Similarly the vegetables like cucurbits, tomato, cabbage, peas, carrot, 

brinjal and chillies are affected by several diseases affecting yield and quality adversely. 

86

Major fruit crops like citrus (lemon, sweet orange, grape fruit), pome fruits (apple, pear), 

banana, grapes, guava and ber are attacked by major diseases like citrus canker, gummosis, 

scab, anthracnose, wilt and powdery mildew etc. 

Diseases and Crop Loss Assessment : 

Crop losses due to diseases can be derived from simple, standardized crop loss 

assessment experiments conducted under normal farm practice and also involve use of 

statistical techniques to summarize and evaluate the validity of the experimental results. 

Techniques for measuring disease and yield loss involve: 

a) Disease assessment : Since disease assessment is the process that generates all the 

data that quantify the progress of disease, it is therefore, critical that assessment methods 

are well defined and standardized. Two principal criteria that must be satisfied prior to 

using the method are that different observers must be able to record similar assessments 

consistently which are also well correlated with actual or measured diseased area. 

Secondly, the assessments must be achieved simply and quickly. Assessment keys 

and standard area diagrams have been developed for many diseases. 

b) Yield Loss Measurement : Yield measurement is as important as disease measurement. 

There is a need to adopt a technique that will allow the data to be standardized and 

collated. This is usually achieved by designating the yield of the healthy plot at each 

location as the reference yield. Yield loss is calculated as the difference in yield between 

a diseased and healthy treatment expressed as percentage of the yield of the healthy 

plot at each location. Several workers have used different methods to estimate crop 

losses quantitatively and models have been developed for different regions. Much of the 

data published on yield losses are very location specific with limited extrapolation 

potential, or they reflect ‘worst case scenarios’ with little corresponding information of 

prevailing disease state in farmers’ fields. There is still a need to develop large area 

databases on crop yield and disease losses so that rational decisions may be made on 

resource allocation for crop protection. 


Agrios, G.N. 2005 Plant Pathology. Academic Press, New York, 922 pp. 

Chiarappa, L. 1971. FAO Manual on the Evaluation and Prevention of Losses by Pests, 

Disease and Weeds, Published by FAO and CAB. 

Roelfs, A.P., Singh, R.P., Saari, E.E. 1992. Rust diseases of wheat. In : Concepts and 

Methods of Disease Management. Mexico, D.F., CIMMYT, 81 pp. 

Waller, J.M., Lenne, J.M. and Waller, S.J. 2002. Plant Pathologist’s Pocket Book. CABI 

Publishing, Oxon, U.K., 516 pp. 

87


DUE TO NEMATODE PESTS IN IMPORTANT CROPS 

R. K. Walia 

Department of Nematology 


Plant parasitic nematodes are ubiquitous and more than 1800 species have been recorded 

so far. Being obligate parasites, they must draw their nutrition from plant hosts, which in 

turn debilitate the plants to some extent. The extent of direct damage by the nematodes to 

plants depends on several factors viz., nematode density in soil, nature of parasitism 

(ectoparasite, endoparasite), host susceptibility, cropping pattern, edaphic factors (soil 

texture, moisture etc.) and ambient climatic conditions (mainly temperature and moisture). 

Nematodes, by themselves, rarely kill the plants to ensure their own survival. However, in 

nature, they interact with other microorganisms (fungi, bacteria, viruses) leading to disease 

complexes, in which nematodes play the role of incitant, aggravator, vector or predisposer 

(indirect damage) of plants to secondary attack by plant pathogens. 

NATURE OF DAMAGE 

Direct Damage 

Nematodes feed upon plant cells and ingest their contents. Individual cells are devoid of 

their cytoplasm one after the, resulting in their death thus causing necrotic areas. 

Intercellular and intracellular migration within the plant tissues may cause mechanical 

injury to the cells. 

Certain nematodes induce special feeding areas in the plant tissues by their enzymatic 

action e.g., ‘giant cells’ produced by root-knot nematode; ‘syncytia’ produced by cyst 

nematodes. These feeding areas formed in vascular tissues disrupt the flow of water and 

nutrients from roots to shoots, resulting in poor plant growth. 

The growing tips of the roots may be killed due to nematode attack. This results in 

cessation of growth and malformation of the overall root system. Nutrient uptake is 

hampered leading to reduced plant growth and yield. 

Some nematodes cause abnormalities in plant growth due to hormonal imbalance e.g., 

production of root galls by root-knot nematode. The functioning of the galled roots is 

adversely affected due to lack of feeder roots and poor absorption and translocation of 

nutrients. 

Nematodes may also feed upon the germinating seedlings (plumule) which may result in 

the pre-emergence death of seedlings. 

Feeding and death of specialized tissues result in direct loss of yield, e.g., feeding on 

floral primordia by wheat seed gall nematode leads to formation of galls instead of seeds; 

destruction of epidermal cells lining resin canals in pine trees by pine wood nematode 

causes cessation of resin production. 

Indirect Damage 

Plant parasitic nematodes are invariably involved with various other microorganisms 

present in the rhizosphere in many ways, leading to disease complexes. Such interactions 

88

of pathogenic organisms are common in nature, and the damage to plants is often 

compounded, than that caused by either pathogen alone. The role played by nematodes in 

such disease complexes may be accounted as follows. 

Mechanical wounding agents: Nematodes cause micropunctures on the root surface 

by their stylets while feeding and penetrating, which may facilitate the infection of several 

types of fungal and bacterial pathogens present in the rhizosphere. 

Host modifiers: Nematode feeding brings about certain biochemical and physiological 

changes in the plant host. This altered physiology of the host may be more conducive 

for fungal and bacterial attack. Nematode feeding may provide a nutritionally improved 

substrate, obstruct plant defence mechanism or destroy chemical antagonists within 

the host, thereby rendering the plant more favourable for colonization by secondary 

pathogens. The necrotic/lesioned tissues resulting from nematode feeding are readily 

attacked by saprophytic microorganisms, causing rotting of such tissues. 

Rhizosphere modifiers: The qualitative and quantitative changes in the root exudates 

of nematode-infected plants may attract secondary pathogens present in the rhizosphere. 

Resistance breakers: In several cases nematodes have been implicated to break the 

resistance in crop varieties to certain fungal diseases. It may be because of mechanical 

wounding or alteration of host physiology by the nematodes. 

Vectors of pathogens: Nematodes may carry on their surface several types of fungal or 

bacterial spores from one spot to another or even inside the plant tissues. But most 

important is their role in virus transmission. A select group of plant parasitic nematodes 

(Xiphinema, Longidorus, Trichodorus, Paratrichodorus) is capable of acquiring, retaining 

and transmitting specific viruses while feeding on plant hosts. The virus particles are 

specifically adsorbed and retained inside the spear and cuticular lining of oesophageal 

lumen. 

Interference in nitrogen fixation: The damage to the nitrogen fixing rhizobial nodules 

by several plant parasitic nematodes is established. Nematodes may cause overall 

reduction in the root system including nodulation, reduce the number and size of the 

nodules, or may invade and feed on the nodules directly. 

SPECIFIC DIAGNOSTIC SYMPTOMS 

Root-knot nematodes (Meloidogyne spp.) 

The above-ground symptoms are not diagnostic. Stunted growth, yellowing of foliage, 

wilting during hot dry periods particularly in broad leaf crops, undersized fruits and reduced 

yields are the common symptoms; and are similar to those induced by nutrient deficiency 

and water stress. Damage is most pronounced when infection occurs in the early stage of 

plant growth, particularly in transplanted crops where seedling mortality may also occur. 

Heavily infected seedlings fail to establish or may remain moribund. Plant mortality is rare 

but whenever it occurs, is the result of secondary infection by other pathogens. 

Below-ground symptoms are typical. Formation of root galls or knots is diagnostic of 

root-knot nematode infection. The intensity of galling and size of the galls are variable 

depending upon root-knot nematode species, nematode population, susceptibility of the 

crop, and age of the crop. Generally, in the initial stage of plant growth, galls (primary galls) 

are small. But as the nematode completes one life cycle, re-infection by second generation 

J2 leads to formation of more galls, the adjacent galls coalesce to form bigger compound 

galls, which are easily visible at later stages of crop growth. 

89

Vegetable crops like tomato, brinjal, okra are highly susceptible and form heavy galling, 

but chillies have very small galls. 

Cucurbits usually have very big galls, so much so that the entire root may become 

swollen. In many such crops, usually eggmasses are formed inside the galls. 

Fleshy edible parts of the crops like carrot, radish and turnip bear small sized galls on 

feeder roots, but tap roots frequently show forking as a result of nematode infection. 

On tuberous crops like potato, besides roots, infection may extend to tubers also. 

Infected tubers show pimple-like growth on the surface, greatly reducing their market 

value. Similarly, in groundnut, pods are also infected causing huge qualitative losses. 

In leguminous plants, nematode galls are distinct from rhizobium nodules. While the 

bacterial nodules are side appendages, soft and can be detached easily, the nematode 

galls are axial swellings of the root itself, hard in consistency, and do not detach. But 

nematode infection hampers bacterial nitrogen fixation due to reduced root system, 

reduction in number and size of nodules, and infection of nodules themselves. 

Size of galls is relatively small in woody roots like in cotton, grapes etc. 

Cereal cyst nematode (Heterodera avenae) 

Patches of stunted plant growth and chlorosis appear when the crop is about 1-2 months 

old. With continuous cropping of hosts, such patches gradually increase in size. Tillering is 

greatly reduced, culms become thinner and weaker. The affected plants may flower 

prematurely and earheads bear fewer grains. In severe infestations, there may not be any 

grain formation. 

Roots become typically bushy with slight swellings marking the sites of nematode 

infection. Appearance of white glistening females on the roots during January/February is 

the only confirmation of nematode infection. 

Potato cyst nematodes (Globodera rostochiensis and G. pallida) 

Introduction of cysts to a new field often goes unnoticed as the nematodes may not 

induce any symptoms for several years till a sizeable population is attained. 

The symptoms appear as small patches of poorly growing plants. Foliage shows wilting 

during hot day time and recover by evenings. The plants remain stunted, foliage starts turning 

yellow from older leaves, which wither away gradually; leaving only a few green leaves on the 

top. Root system is poorly developed, tuber formation is drastically reduced in number and 

size. Spherical white females of the size of a pin-head can easily be observed on the roots 

of infected plants which can be easily uprooted. 

Lesion nematodes (Pratylenchus spp.) 

The above-ground symptoms are not diagnostic and are a manifestation of malfunctioning 

of roots. These include stunting, yellowing of leaves, defoliation, poor fruiting and dieback. 

Roots, however, show discrete elliptical lesions in the initial stages of infection. The lesions 

coalesce as the infection spreads leading to girdling of the roots due to extensive necrosis. 

The overall root system is drastically reduced. The necrotic lesions are often colonised by 

secondary pathogens and rotting sets in. 

Rice root nematode (Hirschmanniella spp.) 

The above-ground symptoms are not clearly manifested and can easily be confused with 

90

nutrient deficiency. In general, there is arrested growth, poor tillering, reduced number of 

earheads and grain weight. On the roots, the initial necrosis intensifies and by the time crop 

matures, the entire root system appears brownish and reduced in size. 

Burrowing nematode (Radopholus similis) 

The disease caused by R. similis on banana is known by different names viz., ‘blackhead 

disease’, ‘banana decline’, ‘rhizome rot’, ‘banana root rot’. The above-ground symptoms are 

manifested by yellowing of outer whorl of leaves, which spreads to inner leaves quickly. This 

is followed by withering of foliage and fruit bunches, eventually the plant dies. Reddish 

elongated lesions that first appear on the roots, gradually enlarge and coalesce leading to 

rotting. The root system is devoid of laterals and overall size of the root system is drastically 

reduced. Rotting extends to rhizomes also. The plants at the bearing stage often ‘topple 

over’ during high winds due to poor anchorage. 

Nematode feeding and movement cause severe necrosis and cavity formation within the 

cortex. The cavities coalesce and break down leading to tunnel formation. Eggs are often 

laid in these cavities, while nematodes move to adjacent healthy tissues. Three to four 

weeks after infection, deep cracks appear on the root surface due to breakdown of the 

tunnels. 

R. similis causes ‘yellows’ disease in black pepper. The first symptoms appear as 

yellowing of a few leaves which gradually extend to all over the vine, leading to complete 

defoliation. The growth of the vine ceases, berry production reduces drastically and the 

vines become unproductive. Death of the vines soon follows. The roots are devoid of laterals, 

there is extensive necrosis on the main roots. 

Citrus nematode (Tylenchulus semipenetrans) 

T. semipenetrans causes ‘slow decline’ or simply ‘citrus decline’ of citrus. The aboveground 

symptoms are generally not discernible during the first few years, during which time 

the nematodes multiply and attain pathogenic levels. Citrus trees more than 7-8 years old 

exhibit decline symptoms, which are manifested by yellowing of leaves, defoliation, premature 

shedding of fruits, reduction in the number and size of fruits, increasing number of dead 

twigs from top, and weak seasonal flushes. 

The feeder roots, however, show typical symptoms. The infested roots appear dark, 

while healthy roots are creamish. Heavily infected roots are covered with soil particles which 

do not go inspite of washing. Such roots are slightly more in diameter and the cortical 

portion can easily be separated from the central stelar part. 

Reniform nematode (Rotylenchulus reniformis) 

The infested plants do not exhibit any diagnostic symptoms either on shoots or on 

roots. General stunted growth, yellowing of leaves, wilting, and deterioration in the quality 

of fruits are commonly observed in most of the hosts. Malformation and discolouration of 

seeds in castor have been reported, which adversely affect the quality and quantity of oil. 

Infected roots generally show necrosis, and feeder roots may be destroyed. 

Wheat seedgall nematode (Anguina tritici) 

The nematode alone causes earcockle disease of wheat. The disease is locally known 

as ‘Gegla’, ‘Sehun’ or ‘Mamni’. 

91

Infected seedlings show basal swelling of the stem after about 20-25 days of germination. 

Subsequently, the leaves emerging from such seedlings are crinkled, curled and twisted. 

The infected plants are generally stunted and grow prostrate with increased tillering. The 

earhead formation may be preponed. The affected earheads are generally shorter and broader. 

Glumes may be loosely arranged, and galls replace the seeds. The galls or cockles are 

smaller, dark brown or black, and irregular in shape compared to healthy seeds. 

A. tritici is often associated with a bacterium, Clavibacter tritici (= Corynebacterium 

tritici) in causing another disease - the ‘yellow ear rot’, which is locally known as ‘tundu’. 

The nematode acts as a vector in this disease complex. The initial symptoms (basal swelling, 

crinkling, curling and twisting of leaves) of tundu are similar to those of earcockle disease. 

However, at the later stage, if high humidity and low temperature conditions prevail longer, 

the bacterium multiplies very rapidly and appears in the form of yellow slimy ooze on the 

surface of leaves and stem. This sticky substance may cover earheads as well. The earheads 

often fail to emerge out of the boot leaves and there may not be any grain formation. Upon 

drying, the yellow sticky ooze becomes brittle and ultimately turns brown. Tundu is more 

damaging than earcockle. 

White tip nematode (Aphelenchoides besseyi) 

A. besseyi causes ‘white-tip’ disease of rice, which is a typical seed-borne disease. 

The seedling growth is stunted and germination is delayed. The most diagnostic symptom, 

however, is the upper 3-5 cm portion of leaf tip turning white or pale yellow at the tillering 

stage. This may appear at nursery stage. Further, the flag leaf is twisted and shortened at 

the apical portion. The infected plants bear shorter panicles and less number of spikelets; 

the kernels are small and deformed in the terminal portion. Secondary panicles may be 

produced from lower nodes if the panicle is sterile. The nematode also causes reduction in 

the total lipid content of the grains. 

Mushroom nematode, Aphelenchoides composticola 

Among the several species of Aphelenchoides reported in association with mushroom, 

A. composticola is considered the most important and is widespread throughout the world, 

including India. A. composticola is basically mycophagous and feeds on the fungus mycelium. 

The growth of Agaricus bisporus (button mushroom) is adversely affected and fruiting is 

drastically reduced. The nematode may be introduced into the mushroom beds along with 

compost, casing soil, irrigation water, insects etc., and attains peak populations quickly 

since the life cycle duration is very short (8 days at 23° C). An initial number of 9 nematodes 

per 300 g compost can destroy the mycelium completely. The initial symptoms of nematode 

infection may appear as spawn turning brown followed by sparse and patchy appearance of 

the mycelium, which turns stingy in nature. The compost surface also sinks; followed by 

extremely poor sporophore yields, and reduction in the duration of crop. 

Foliar nematodes (Aphelenchoides fragariae and A. ritzemabosi) 

Both A. fragariae and A. ritzemabosi are temperate climate species and are widespread 

in Europe, Canada, Australia, New Zealand and South Africa. In India, these have been 

reported from Jammu & Kashmir and Himachal Pradesh. The preferred hosts of A. ritzemabosi 

are plants belonging to family Compositae with chrysanthemum as the main host; while A. 

fragariae is considered a problem on strawberry but its host range extends to families 

Liliaceae, Ranunculaceae, Primulaceae, besides some ferns. 

Both the species feed ectoparasitically on buds and endoparasitically on leaves. During 

high humidity and rainy season, the nematodes ascend up the stem in a thin film of water 

92

DIAGNOSTIC SYMPTOMS OF NEMATODE PESTS' ATTACK IN IMPORTANT CROPS 

Root knot disease of tomato and potato tuber 

(C.O. Meloidogyne sp.) 

Earcockle disease of wheat 

(Left = Healthy) 

(C.O. Anguina tritici) 

Rice root knot disease 

(C.O. Meloidogyne graminicola) 

Slow Decline of Citrus (C.O. Tylenchulus semipenetrans) 

Tundu disease of wheat (Left = Healthy) 

(C.O. Anguina tritici + Clavibacter tritici) 

Molya disease of wheat (inset = infected 

roots) (C.O. Heterodera avenae) 

White tip disease of rice 

(C.O. Aphelenchoides 

besseyi) 

Swollen Ufra Ripe Ufra 

Ufra disease of rice (C.O. Ditylenchus angustus) 

Infected roots Healthy roots

covering the plant, enter the leaves through stomatal openings, and feed on the mesophyll 

tissues. Infection spreads from lower to upper leaves, and the symptoms appear as tiny 

brown spots on leaves initially, which enlarge to acquire inter-veinal angular spots. Nematode 

feeding on buds results in a ‘blind’ plant (A. fragariae on strawberry) or undersized and 

distorted flowers (A. ritzemabosi on chrysanthemum). The nematodes can survive in a 

quiescent stage inside the dormant buds or dried up leaf tissues. A. fragariae causes 

‘cauliflower’ disease in strawberry in the presence of bacterium Clavibacter fasciens. 

Rice stem nematode (Ditylenchus angustus) 

The first symptoms appear when the crop is two-three months old in the form of chlorosis 

and yellow streaks on the upper leaves. Later two types of symptoms are manifested: 

Swollen Ufra in which case the panicles fail to emerge and the stalks show a tendency to 

branch; and Ripe Ufra when panicles emerge but are distorted and sterile. Such panicles 

produce grains only near the tip; their peduncles turn brown and discoloured. The severity of 

disease is enhanced under water logged conditions. 

CROP LOSS ESTIMATIONS 

Techniques : The economic importance of a plant parasitic nematode is judged by its 

parasitic or pathogenic potential, geographic distribution and value of the crop. While the 

economic threshold levels in respect of major nematode pests have been worked out on 

specific crops, still however, it is very difficult to estimate the extent of losses inflicted by 

nematodes to the crops due to certain inherent problems. The first and the foremost problem 

is the heterogenous distribution of phytonematodes in a field. Further, the phytonematodes 

occur in polyspecific communities. Crop loss assessments due to nematodes are usually 

based on field trials involving the use of nematicides. The increase in crop yield following 

nematicidal treatments compared to untreated plots is usually related to that avoided by 

nematode control. Non-availability of exclusive nematicides is another hurdle in attributing 

crop losses due to nematodes alone. 

Methods of assessing crop losses due to phytonematodes have been discussed in detail 

by Teng (1985), Ravichandra (2010) and Kanwar & Bajaj (2011). 

Estimations : The most authentic and widely quoted estimate on crop losses due to 

plant parasitic nematodes was provided by Prof. J. N. Sasser, who led an International 

Meloidogyne Project during 1980’s. Overall average annual loss of world’s major crops due 

to damage by plant parasitic nematodes was estimated to be 12.3%, which amounts to US 

$ 77 billions annually based on 1984 production figures and prices. 

In India, the annual loss due to cereal cyst nematode, Heterodera avenae in wheat and 

barley was estimated to be Rs 32 million and 25 million, respectively, in Rajasthan alone. 

For seed gall nematode, Anguina tritici (alone or in combination with a bacterium), the 

annual yield loss amounting to Rs 70 million was estimated in wheat in north India. An 

annual loss of Rs 20 million was assessed in coffee due to lesion nematode, Pratylenchus 

coffeae in an area of about 1000 hectares in Karnataka state alone (van Berkum & Seshadri, 

1969). Another estimation on crop losses due to phytonematodes in India was made under 

the aegis of AICRP (Nematodes). Twenty four different crops were selected, and a minimum 

of 10% cultivated area under each crop was considered as infested. On this basis, the 

national loss due to plant parasitic nematodes was worked out to be Rs 21068.73 million 

(Jain et al., 2007). Seshadri & Gaur (1998) estimated that nematodes inflict 5% losses in 

oilseed crops, 8% in pulses, 10% in fruits and 12% in vegetable crops; the total amounting 

to Rs 242,000 millions per year. 

93

Estimated annual yield losses due to damage by plant parasitic nematodes world wide. 

Life sustaining crops Loss (%) Economically important crops Loss (%) 

Banana 19.7 Cacao 10.5 

Barley 6.3 Citrus 14.2 

Cassava 8.4 Coffee 15.0 

Chickpea 13.7 Cotton 10.7 

Coconut 17.1 Cowpea 15.1 

Corn/Maize 10.2 Eggplant 16.9 

Field bean 10.9 Forages 8.2 

Millets 11.8 Grape 12.5 

Oat 4.2 Guava 10.8 

Peanut 12.0 Melons 13.8 

Pigeonpea 13.2 Misc. others * 17.3 

Potato 12.2 Okra 20.4 

Rice 10.0 Ornamentals 11.1 

Rye 3.3 Papaya 15.1 

Sorghum 6.9 Pepper 12.2 

Soybean 10.6 Pineapple 14.9 

Sugarbeet 10.9 Tea 8.2 

Sugarcane 15.3 Tobacco 14.7 

Sweet potato 10.2 Tomato 20.6 

Wheat 7.0 Yam 17.7 

Average 10.7 Average 14.0 

Overall average 12.3% 

*Additional miscellaneous crops of economic importance, especially for food or export 


Jain, R. K., Mathur, K. N. and Singh, R. V. 2007. Estimation of losses due to plant parasitic 

nematodes on different crops in India. Indian Journal of Nematology, 37 : 219-221. 

Kanwar, R. S. and Bajaj, H. K. 2011. Assessment of crop losses due to nematodes. In: 

Handbook of Practical Nematology (Eds. H. K. Bajaj, R. S. Kanwar & D. C. Gupta), 

Scientific Publishers (India), pp. 97-100. 

Ravichandra, N. G. 2010. Methods and Techniques in Plant Nematology. PHI Learning Pvt. 

Ltd., New Delhi. 595 pp. 

Sasser, J. N. (1989). Plant Parasitic Nematodes: The Farmer’s Hidden Enemy. A Cooperative 

Publication of the Department of Plant Pathology and the Consortium for International 

Crop Protection. North Carolina State University, Raleigh, USA, 115 pp. 

Seshadri, A. R. and Gaur, H. S. 1998. Integrated nematode management approaches for 

sustainable agriculture. In : Changing scenario in farming practices – policies and 

management. (Ed. Kushwaha, K. S.). Kushwaha Farm Book Series, pp. 296-319. 

Teng, P. S. 1985. Crop loss assessment methods: Current situation and needs. In: An 

Advanced Treatise on Meloidogyne, Vol. II. Methodology (Eds. K. R. Barker, C. C. Carter 

& J. N. Sasser), A Co-op Publ. of Dept. of Plant Pathology and USAID, North Carolina 

State University Graphics, pp. 149-158. 

94

DIAGNOSTIC SYMPTOMS OF MACRO AND 

MICRONUTRIENTS' DEFICIENCY IN IMPORTANT CROPS 

J. P. Singh and Dev Raj 

Department of Soil Science, 

CCS Haryana Agricultural University Hisar 

A mineral element is considered essential to plant growth and development if the element is 

involved in plant metabolic functions and the plant can not complete its life cycle without 

that element (Arnon and Stout 1939). The seventeen nutrients recognized essential for plant 

growth among them carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), 

potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S) are macronutrients (nutrient 

required in large quantity, more than that of Fe). Iron (Fe), manganese (Mn), zinc (Zn), 

copper (Cu), boron (B), molybdenum (Mo), chlorine (Cl) and nickel (Ni) are micronutrients 

(nutrient required in small quantity). Carbon, hydrogen and oxygen constitute 90 to 95 percent 

of the plant dry matter weight and are supplied through CO 2 and water. Remaining six nutrients 

are further divided in to primary (N, P, K) and secondary (Ca, Mg, S) nutrients. Micronutrient 

are subdivided into micronutrient cations (Fe, Mn, Zn, Cu, Ni) and anions (B, Mo, Cl) depending 

upon the form in which plant absorb them (Tisdale et al., 1993). 

Usually the plant exhibits visual symptoms indicating a deficiency in a specific nutrient, 

which normally can be corrected or prevented by supplying that nutrient. A nutrient is deficient 

when the concentration of that nutrient is low enough to limit yield severely and distinct 

deficiency symptoms are visible. With moderate or slight deficiencies, symptoms may not 

Key for identifying nutrient deficiency symptoms in crops. 

Nutrient Deficiency symptoms 

Symptoms appear first on older leaves. 

Nitrogen Chlorosis starting from leaf tips. 

Potassium Necrosis on leaf margins. 

Magnesium Chlorosis mainly between veins (which remain green). 

Phosphorus Dark green or purple colour on stem, leaf is redish colour. 

Zinc Pale brown or dusty brown necrotic patches on the middle of leaf, 

shortened internodes. 

Symptoms appear first on younger leaves. 

Sulphur Mottled yellow green leaves with yellowish veins. 

Iron Mottled yellow green leaves with green veins. 

Manganese Brownish black spot (on legumes and potato). 

Copper Younger leaf has white tip. Leaf dropping. 

Molybdenum Young leaf wilt and die along margins. Chlorosis of older leaves due 

to inability to properly utilize nitrogen. 

Chloride Wilting of upper leaves, then chlorosis. 

Symptoms on bud leaves 

Calcium Emergence of primary leaves delayed, terminal buds deteriorate, leaf 

tips may be stuck together. 

Boron Leaves near growing point yellowed, growth bud appear white or 

brownish dead tissue. 

95

e visible, but yield will still be reduced. The deficiency symptoms are nutrient specific and 

show different pattern in crops for different essential nutrients. One has to look carefully to 

identify the deficiency symptoms since visual deficiency symptoms can be caused by many 

factors other than a specific nutrient stress. A brief key to identify the nutrient deficiency 

symptoms was given by Finck (1992) is presented here. However, a correct interpretation of 

deficiency symptom requires a great deal of field experience and should always be 

corroborated by the soil and plant analysis. 

In Indian soils, multiple nutrient deficiencies can occur at the same time and some 

symptoms are similar for different elements, making it even more confusing. Visual symptoms 

are only the consequence of metabolic disturbances and different causes can lead to very 

similar syndromes. Hence, nutrient deficiency can be confused with symptoms of disease, 

drought, excess water, genetic abnormalities, herbicide and pesticide damage and insect 

attack. Visual diagnosis of nutrient deficiency provides a valuable means of assessing the 

nutritional conditions of a crop. It should be practiced only by experts as it requires much 

experience. Furthermore, visual evaluation of nutrient stress should be used only as a 

supplement to other diagnostic techniques (i.e., soil and plant analysis). Description of 

nutrient deficiency symptoms in important crops along with colored plates showing typical 

deficient symptoms in some crops (Sharma and Kumar, 2001) are presented here as a field 

guide to identify the nutrient deficiency in the field and how they might be prevented or 

remedied. 

WHEAT (Triticum aestivum Linn.) 

Nitrogen 

Deficiency symptoms : 

i. Deficient plants have slow growth rate, poor tillering resulting in reduced grain yield. The 

stem has a spindly appearance. 

ii. Deficiency symptoms i.e. yellowing or chlorosis usually appear first on lower leaves. In 

mild deficiency the entire plant appears uniformly light green in color. 

iii. Under severe N deficiency, a pale yellow chlorosis begins at the tip of old leaf and 

progresses towards the leaf base. 

iv. As the symptom advances, lower leaves turn pale brown, withers and die. 

Amelioration : 

i. Apply N basal dose as per soil test based recommendation. 

ii. Top dress soluble nitrogenous fertilizers such as urea in split doses. 

iii. For quick recovery in standing crops, apply 2 to 2.5% urea solution as foliar spray and 

repeat every 10 to 15 days till the deficiency symptoms disappear. 

Phosphorus 


i. Deficient plants remain dark green, stunted, thin and spindly. 

ii. The number of tillers and grain head size severely reduced resulting in low grain yield. 

iii. Deficiency symptoms appear first in older leaves while young leaves usually remain 

unaffected. 

iv. Older leaves develop a dark purple color on the leaf tip which progresses towards the base. 

v. In sever deficiency situations, affected leaf tissues show purple discoloration. 

vi. Stem and leaf sheaths of lower leaves express purple red color. 

96


i. Drill/place basal dose of P as per soil test based P recommendations. 

ii. Apply soluble P fertilizer with first irrigation in standing crops. 

Potassium 


i. In the first instance there is only reduction in growth rate due to hidden hunger. The 

deficiency only becomes recognizable as it advances in severity. 

ii. Visual symptoms do not immediately appear due to K deficiency. 

iii. On older leaves, symptoms appear as pale yellow chlorosis and necrosis begins at the 

tips of leaves and advancing along the margins towards the base, usually leaving the 

midvein alive and green. 

iv. In acute deficiencies, leaves turn dark brown and die. 

v. Potassium deficient tillers die before producing heads, while mature tillers produce small 

heads with few grains. 


i. Apply K as basal dose as per soil test based fertilizer recommendations. 

ii. In standing crops, apply soluble K fertilizers with irrigation water. Foliar sprays are usually 

not recommended since large numbers of sprays are needed to fulfill the K requirement 

of the crop. 

Sulphur 


i. Deficiency symptoms appear first on younger leaves. General yellowing of the plant is 

observed which is more prominent between the veins. Older leaves remain green. 

ii. In n advance stage, the pale yellow youngest leaves turn white without necrosis. 

Amelioration: 

i. Apply recommended basal dose of S by mixing either elemental S or gypsum with surface 

soil well before sowing. 

ii. In deficient standing crops, apply water soluble sulphur fertilizer with irrigation water. 

Iron 


i. A deficiency of Fe shows up first in the young leaves of plants. 

ii. The young leaves develop interveinal chlorosis, which progresses rapidly over the entire 

leaf. 

iii. Under acute deficiency condition, the entire leaf bleaches to a bright yellow to white color. 


i. In general soil application of inorganic iron sources are not effective in correcting Fe 

deficiency. 

ii. Correction of Fe deficiencies is done mainly with foliar application of Fe. Apply foliar 

spray of ferrous sulphate or iron chelate (0.5 % solution) on standing crop. Foliar sprays 

need to be repeated at 10 -15 days interval and 2 to 3 sprays are often required. 

97

Zinc 


i. Wheat cultivars show strong hidden hunger for Zn and symptoms of Zn deficiency appear 

only in acute deficiency conditions. 

ii. Zinc is partly mobile in plants and deficiency symptoms first appear on middle leaves. 

Initially upper (younger) and lower leaves remain unaffected. 

iii. Occurrence of light green, yellow or white areas between the veins of leaves. 

iv. As the deficiency become more severe, brown necrotic patches and extend outwards 

towards the tip and base of the leaf. 


i. Analyze the soil before sowing for plant available zinc and apply zinc sulfate commonly 

at 25-30 kg/ha once every two years in zinc deficient soils. 

ii. Spray zinc sulfate (0.5% solution) on standing crop 2 to 3 week after seedlings emergence. 

Repeat the spray if deficiency persists. 

Copper 

Deficiency Symptoms : 

i. Deficient plants appear limp and wilted even in adequate soil moisture conditions. 

ii. Severe deficient plants can have a twisted young leaves. 

iii. In acute deficiency, young leaf tips turn pale brown, die and twist in to tight tubes- a 

specific symptoms of Cu deficiency in wheat. 


i. Soil and foliar applications are both effective. 

ii. In standing crop apply copper sulfate (0.2 to 0.5 %) as a foliar spray. Repeated sprays 

are required if symptoms reappear. 

Manganese 

Deficiency Symptoms : 

i. Manganese deficient plants are chlorotic and slow to mature. 

ii. Develop small, roughly circular, grey white specks on older leaves. 

iii. Leaves may kink or droop at the base of the blade or wherever the spotting is intense. 


i. Analyze the soil before sowing for plant available manganese. 

ii. Apply foliar spray of manganese sulphate @ 0.5 percent and repeat the spray if deficiency 

persists. 

RICE (Oryza sativa L.) 

Nitrogen 


i. When plants are deficient, they become stunted, thin and spindly and panicle size is 

reduced. The number of tiller is also reduced. 

ii. The chlorosis followed by necrosis is started at tip of older leaves and proceeds towards 

the base. Slight delay in heading and kernel weight may also be reduced. 

98


i. Apply soil test based fertilizer recommendations. 

ii. Top dress soluble fertilizer such as urea in two split doses. 

iii. For quick recovery in standing crop, apply 2 to 2.5% urea solution as foliar spray and 

repeat every 10 to 15 days till the deficiency symptoms disappear. 

Phosphorus 

Deficiency : 

i. Phosphorus deficient plants usually shows stunted growth with erect and dark green 

leaves. Number of tillers is also reduced. 

ii. In some cultivars, a purple color may develop first on the leaf tips and progress towards 

the leaf base. 

iii. In severe deficiency, the entire leaf turns dark brown and dies. 


i. Apply soil test based P fertilizer recommendations at the time of planting. 

ii. In case P deficient symptoms appear in standing crop, apply water soluble P fertilizers 

with irrigation water. 

Potassium 


i. Visual deficiency symptoms for K are rarely noticed under field conditions. Rice has 

strong hidden hunger symptom for K. 

ii. Under later growth stage, Yellowish brown discoloration followed by necrosis begins at 

the tips of lower leaves and advances down the margins towards their base leaving the 

mid vein and the surrounding tissue green. 

iii. In acute deficiencies, rust brown spots on older leaves and leaf bronzing are formed. 


i. Apply soil test based K fertilizer recommendations at the time of transplanting. 

ii. Apply water soluble K fertilizers with irrigation water if K deficiency symptoms appear in 

at the later stage of crop growth. 

Sulphur 


i. Plants are stunted, thin and spindly with small heads leading to delayed maturity. 

ii. Chlorosis appears first on younger leaves, while older leaves usually remain green. 

iii. The yellowing appears uniformly on veins and interveinal tissues. 


i. Analyze the soil before sowing to measure the amount of plant available sulphur. 

ii. Apply recommended dose of S by mixing either elemental S or gypsum in to the soil 

surface well before transplanting. 

iii. In standing crop apply soluble S fertilizers with irrigation water. 

00

Iron 


i. Iron deficiency appears first on younger leaves. The leaves show temporary fading of 

interveinal tissues, Plant can recover and regain a normal appearance with time. 

ii. If the deficiency persists, the interveinal chlorosis is developed on young leaves. 

iii. In severe deficiency, emerging leaves become pale yellow to white and entire leaf bleaches 

to a papery white appearance. 


i. In general soil application of inorganic iron sources are not effective in correcting Fe 

deficiency. 

ii. Correction of Fe deficiencies is done mainly with foliar application of Fe. Apply foliar 

spray of ferrous sulphate or iron chelate (0.5 % solution) on standing crop. Foliar sprays 

need to be repeated at 10 -15 days interval and 2 to 3 sprays are often required. 

Zinc 


i. Zinc deficiency symptoms in rice commonly occur between 2 to 4 weeks after 

transplanting. 

ii. Loss of turgidity of leaves. The dusty browns to bronze blotches are developed on lower 

leaves. 

iii. In severe deficiency, the small blotch enlarges and covers the whole leaf and affected 

leaf turns bronze and dries. 


i. Analyze the soil before sowing for plant available zinc and apply zinc sulfate commonly 

at 25-30 kg/ha once every two years in zinc deficient soils. 

ii. Two kg zinc sulphate/ha may be applied in crop nurseries 

iii. Spray zinc sulfate (0.5% solution) on standing crop 2 to 3 week after seedlings 

emergence. Repeat the spray if deficiency persists. 

Manganese 


i. Manganese deficiency is not common in rice under field conditions. 

ii. Deficiency causes stunting of plants and interveinal chlorosis of new leaves but does not 

have any effect on tillering. 


i. Analyze the soil before sowing for plant available manganese. 

ii. Apply foliar spray of manganese sulphate @ 0.5 percent and repeat the spray if deficiency 

persists. 

COTTON (Gossypium hirsutum L.) 

Nitrogen 


i. Cotton plant show stunted growth, less number of branches and yellowish green color of 

foliage. 

100

NUTRIENTS' DEFICIENCY SYMPTOMS IN DIFFERENT CROPS 

Phosphorous deficiency 

Potassium deficiency 

Nitrogen deficiency in rice Nitrogen deficiency in wheat 

P deficiency in rice seedling P deficiency in maize 

K deficiency in rice K deficiency in wheat 

Iron deficiency 

Fe deficiency in rice Fe deficiency in sugarcane 

Sulphur Deficiency (advance stage) 

Sulphur Deficiency (early stage)

NUTRIENTS' DEFICIENCY SYMPTOMS IN DIFFERENT CROPS 

Zinc deficiency 

Zn deficiency in rice Zn deficiency in wheat 

Copper deficiency 

Cu deficiency in wheat Cu deficiency in young leaf of wheat 

Mangnese deficiency 

Mn deficiency in wheat Mn deficiency in oat

ii. Yellowing first appears on older leaves . In severe cases of deficiency, leaves dry up and 

shed prematurely. 

iii. There is less number of boll and they also tend to shed due to nitrogen deficiency. Early 

opening of bolls and number of seed and their size is also reduced. 


i. Apply soil test based fertilizer recommendation. 

ii. Top dress soluble fertilizers such as urea in two splits doses in variety and three splits 

doses in hybrids. 

iii. For quick recovery in standing crops, apply urea (2.5% solution) as foliar spray and 

repeat every 10 to 15 days. 

Phosphorus 


i. The most common indicator of P deficiency in cotton are dark green foliage, reduced 

size of leaves, dwarf type of plants and less number of branches. 

ii. Deficiency symptoms appear first in lower leaves. 

iii. Flowering is delayed and boll retention is also poor. 

iv. In severe deficiency, relatively few cotton bolls are developed and maturity is delayed. 



ii. Apply water soluble P fertilizers in standing crop along with irrigation water in case P 

deficiency is observed in the field. 

iii. In standing crops, foliar spray of DAP (2%) at 10-15 days interval can also applied 

Potassium 


i. Cotton rust or potash hunger is common in crop grown in K deficient soils. 

ii. Yellowish white mottling appears on the older leaves. The leaves then change to light 

yellow green and yellow spots appear between veins. 

iii. In severe deficiency, the centre of the spots dies and numerous brown spots occur 

around the margins and between the veins. The margins breakdown first and curls 

downward. 

iv. In late season K deficiency, the whole leaf finally becomes reddish brown in color, dries and 

shed prematurely. The boll size is reduced and many bolls fail to open or they partly open. 



ii. In case K deficiency appears, apply soluble K fertilizers with irrigation water in standing 

crop. Foliar sprays are usually not recommended since large numbers of sprays are 

needed to fulfill crop requirements. 

Sulphur 


i. Sulphur is very important for cotton crop and its requirement is higher than phosphorus. 

ii. Deficiency symptoms appear first and become more severe on younger leaves. The young 

leaves become pale yellow while older leaves usually remain green. 

101

iii. In advance stage, the pale yellow youngest leaves turn white without necrosis. 

iv. The pattern of yellowing on the entire leaf appears uniform, affecting both vein and 

interveinal tissues to the same degree. 

v. The seed weight is reduced and oil content is also reduced in sulphur deficient plant. 


i. Analyze the soil before sowing for available sulphur. 

ii. Apply recommended dose of S as basal by mixing either elemental S or gypsum with 

surface soil well before sowing. 

iii. Apply SSP in place of DAP for providing both P and S to the cotton crop. 

iv. In deficient standing crop, apply soluble sulphur fertilizer with irrigation water. 

Iron 


i. About six weeks growth, plants grown in low iron supply soil show interveinal chlorosis 

of young leaves. 

ii. The interveinal chlorosis gradually intensifies and the young chlorotic leaves develop 

brown necrotic spots. 

iii. In acute deficiency, there is loss of lamina in the interveinal areas. 


i. Analyze the soil before sowing for plant available iron. 

ii. In standing crop apply a foliar spray of ferrous sulphate or iron chelates (0.5 % solution). 

Foliar spray s need to be repeated in 10 -15 days interval and 2 to 3 sprays are often required. 

Zinc 


i. Zinc deficiency symptoms in cotton appear three weeks of sowing, causing bronzing of 

new and older leaves. 

ii. The brown color spots extend from leaf tip towards the base and scorching of leaves 

occurs on the margins. 

iii. Interveinal chlorosis in the form of golden yellow color observed in the middle leaves. 

iv. The old and middle leaves also show upward and downward cupping tendency (cup shape 

of leaf). 

v. Plants bear less fruits and opening of boll is abnormal. 

vi. The internodes are shortened and plant show bushy appearance. 


i. Analyze the soil before sowing for plant available zinc. 

ii. Apply zinc sulphate at 25-30 kg/ha once every two years in zinc deficient soils. 

iii. In standing crop, spray 2.5 kg zinc sulphate plus un-slaked lime (500g) in 500 liter water 

2 to 3 week after seedling emergence. 

Manganese 


i. Leaf cupping and interveinal chlorosis on younger leaves indicates Mn deficiency. 

ii. Manganese deficiency delays the flowering. 

102

iii. Manganese deficiency symptoms resemble with Zn and Fe deficiency, so the soil and 

plant testing is required to identify the deficient nutrient. 


iii. Analyze the soil before sowing for plant available manganese. 

iv. Apply foliar spray of manganese sulphate @ 0.5 percent and repeat the spray if deficiency 

persists. 

PEARLMILLET (Pennisetum typhoides) 

Nitrogen 


i. In mild deficiencies, the plant appears light green in color. 

ii. In severe deficiency, a pale yellow chlorosis begins at the tip of older leaves, and then 

progress towards the base along the midrib in a V- shaped pattern. 

iii. In the advance stage, the pale yellow chlorosis is followed by pale brown necrosis. 



ii. Top dress soluble fertilizer such as urea in two splits doses. 

iii. For quick recovery in standing crop, apply urea (2%) solution as a foliar spray and 

repeat the foliar spray every 10 to 15 days interval 

Phosphorus 


i. Deficient plant appears dark green, stunted, thin and spindly and has delayed maturity. 

ii. Dark green older leaves turn purple or purple red in color. Stem and leaf sheath of lower 

leaves also turn purple red in color. 


i. Apply soil test based P fertilizer recommendations as basal. 

ii. Apply soluble P fertilizers with irrigation water if the P deficiency appears in standing crop. 

Potassium 


i. Potassium deficiency causes shortening of the internodes, dwarfing of plants and a 

general loss of healthy, green growth. 

ii. Marginal chlorosis develops on older leaves starting from the leaf tip and progresses 

towards the base. 

iii. The Chlorosis followed by necrosis advances down the margins towards the base leaving 

the mid-vein and surrounding tissue pale green. 


i. Apply full dose of K based on soil test at the time of sowing. 

ii. In case K deficiency appears in standing crops, apply soluble K fertilizers with irrigation 

water. 

Sulphur 

Deficiency : 

i. Deficient plants appear pale green, thin, spindly and stunted with delayed maturity. 

103

ii. The young leaves become dull or bright yellow, while older leaves usually remain green. 

iii. The yellowing of leaves appears uniformly on veins and interveinal tissues 


i. Apply the soil test based dose of sulfur by mixing either elemental S or gypsum in to 

the soil surface well before sowing. 

ii. In deficient standing crops apply water soluble S fertilizers with irrigation water. 

Iron 


i. In mild deficiencies the top most leaves of plants show temporary fading of interveinal 

tissues. 

ii. If the deficiency persists, the interveinal tissues of affected leaves turn a distinct pale 

yellow with prominent green veins. 

iii. In severe deficiency, the prominent green veins also fade and become light green to pale 

yellow. 


i. Analyze the soil before sowing to measure the amount of plant available iron. 

ii. In standing crop, apply 0.5% ferrous sulphate as foliar spray and 2 to 3 foliar sprays are 

required at 10 days intervals. 

Zinc 


i. The internodes are shortened and height is restricted. 

ii. White to yellow broad bands of bleached tissue appear on each side of the midrib, 

beginning at the base of the leaf. The midrib and the leaf margins remain green 

iii. Zinc deficiency resemble to Fe and Mn deficiency, However, in the case of Fe and Mn 

the interveinal striping runs the full length of the leaf, while in Zn deficiency it occurs 

mainly on the basal half of the leaf. 

iv. If the deficiency persists and becomes more severe, the youngest leaves turn pale green and 

white broad bands appear between the midrib and margin in the basal half of the leaf. 


i. Analyze the soil before sowing to measure the amount of plant available zinc. 

ii. Apply 25 to 30 kg zinc sulphate/ha in zinc deficient soils at the time of sowing. 


Arnon, D. I. and Stout, P. R. 1939. An essentiality of certain elements in minute quantity for 

plants with special reference to copper. Plant Physiology, 14: 371- 375. 

Finck, A. 1992. Fertilizers and their efficient use. In IFA World Fertilizer Manual, Paris, 

France. 

Sharma, M.K. and Kumar, P. 2011. .A Guide to Identifying and Managing Nutrient Deficiencies 

in Cereal Crops. (K. Majumdar, T. Satyanarayana, R. Gupta, M.L. Jat, G.D. Sulewski, 

D.L. Armstrong Eds.) International Plant Nutrition Institute (IPNI), Norcross, GA, USA. 

International Maize and Wheat Improvement Center (CIMMYT) EI Batan, Mexico. 

Tisdale, S.L., Nelson, W.L., Beaton, J.D. and Havlin, J.L. 1993. Soil Fertility and Fertilizers. 

Prentice Hall of India Private Limited, New Delhi 110001. 

104

DIAGNOSTICS AND ASSESSMENT OF LOSSES DUE 

TO INSECT-PESTS IN STORED DRY FRUITS 

Ajay K. Sood 


CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur (H.P.) 

Dry fruits have a long tradition of use dating back to the fourth millennium BC in 

Mesopotamia, and are prized because of its sweet taste, nutritive value and long shelf life. 

The dried seeds of nuts are eaten as raw, roasted, pureed or used as flour. Nuts are the best 

source of protein, fats and vitamin E. They contain cholesterol free unsaturated fats, 

magnesium, chromium, zinc and manganese. Today, dried fruit consumption is widespread. 

Amongst the different dried fruits as listed in Table 1, half of the dried fruits trade comprises 

raisins. 

Table 1. Dry fruits being produced/ consumed in India 

Common name Botanical name Major producing states 

Almond Prunus amygdalus Batsch. Himachal Pradesh, Jammu & 

Kashmir, Uttrakhand 

Apricot (Prunes) Prunus armeniaca L. Himachal Pradesh, Jammu & 


Cashew nut Anacardium occidentale L. Andhra Pradesh, Goa, 

Karnataka, Kerala, Maharashtra, 

Orissa 

Copra (Coconut) Cocos nucifera L. Andhra Pradesh, Karnataka, 

Kerala, Orissa, Tamilnadu 

Date (Date palm) Phoenix dactylifera L. Gujarat, Rajasthan (Major 

proportion being imported) 

Pecan nut Carya illinoensis (Wangenhi) Himachal Pradesh, Jammu & 

K. Koch Kashmir, Uttrakhand 

Pine cone (Chilgoza) Pinus gerardiana Wall. ex.D.Don Himachal Pradesh (Major 

proportion being imported) 

Pistachio nut Pistacia vera L. Being imported 

Raisin Vitis vinifera L. Andhra Pradesh, Haryana, 

Karnataka, Maharashtra, Punjab, 

Tamilnadu 

Walnut Juglans regia L. Himachal Pradesh, Jammu & 


All dried fruits are susceptible to insect infestation. Normally, dried fruits have moisture 

content above 10% and, therefore, are liable to the attack by pest species. If fruits be dried 

to a level where insects could not exist on them, they would become unattractive to 

consumers. A fairly soft pliable product is desirable. The high temperatures used for removing 

moisture are fatal to insects in the dry fruits. Wherever dried fruits are produced globally, 

their chief insect pests are the same species. They have been distributed by commerce, 

probably for several thousand years. A stored food product may become infested at the 

105

processing plant or warehouse, in transit, at the store, or right in consumers’ home. Most of 

the stored dry fruit insects are also the pests of stored grains or other commodities. 

In India, eighteen insect-pests belonging to two insect orders namely, Coleoptera and 

Lepidoptera have been found associated with important dry fruits (Table 2). In the forthcoming 

text, the diagnostic features of major insect-pests of dry fruits based on the damage symptoms 

and insect characteristics are being enumerated in the order of their significance. 

I. BEETLES AND WEEVILS 

Sawtoothed Grain Beetle, Oryzaephilus surinamensis (Coleoptera: Silvanidae) 

Merchant Grain Beetle, Oryzaephilus mercator 

Both grubs and adults inflict damage. The insect is having preference to dry foods. 

Adults and grub cause roughening of surface and off- odour in the food. Dry fruits with higher 

percentage of broken, dockage and foreign matter sustain heavy infestation, which leads to 

heating. Where sawtoothed grain beetles are numerous, populations of the Indian meal moth 

do not build up to high levels. 

Tobacco/ Cigarette Beetle, Lasioderma serricorne (Coleoptera: Anobiidae) 

It is a cosmopolitan insect but prefers warm environment. It feeds on large number of 

food varying from spices, dried fruis, chocolate, cocoa and tobacco leaves. Grub causes the 

damage by making small galleries in the host. 

Rust Red Flour Beetle, Tribolium castaneum (Coleoptera: Tenebrionidae) 

Confused Flour Beetle, Tribolium confusum 

The flour beetles are worldwide pest of milled products and processed foods. Flour beetles 

are secondary pests of whole kernels/ grains and primary pests of flour and other milled 

products. In grains, embryo or germ portion is preferred. They construct tunnels as they 

move through flour and other granular food products. In addition they release gaseous quinines 

in the food, which may produce a readily identifiable acid odour in heavy infestations. 

Lesser grain borer/hooded grain borer, Rhizopertha dominica (Bostrychidae: Coleoptera) 

Grubs and adults cause damage. Adults are voracious feeders. The grubs eat out the 

starchy contents of the grains which are reduced to frass and waste flour. The first stage 

larva is straight hence it can bore easily into sound grain but in the later stages of growth it 

is curved, therefore, it becomes difficult for them to penetrate the grain. The grubs which are 

unable to penetrate the grain feed on the waste flour left by the adults. 

Khapra Beetle, Trogoderma granarium (Coleoptera: Dermestidae) 

Adults are harmless. Grubs inflict damages starting from germ portion, surface scratching 

and devouring the kernel reducing to frass. Excessive moulting results in loss of market 

value due to insanitation caused by the casted skin, frass and hair. Crowding of larvae leads 

to unhygienic conditions in warehouses. Damage is confined to peripheral layers of bags in 

bulk storage. 

Rice Weevil, Sitophilus oryzae (Coleoptera: Curculionidae) 

This is the most destructive insect-pest of stored cereals in the world and is capable of 

damaging the whole grains only. Both, adults and grubs damage the kernel on which they feed 

voraciously and render them unfit for human consumption. The grub is more injurious than adult. 

In case of heavy infestation, the food commodity becomes a mass of broken matter. 

106

Foreign Grain Beetle, Ahasverus advena (Coleoptera: Silvanidae) 

The foreign grain beetle is found in both tropical and temperate regions. It is small in 

size (2 mm in length). Adults are reddish-brown in colour. This beetle can be distinguished 

chiefly by two peg- like projections behind the head on each front corner of the pronotum, 

and its club-shaped antennae. They are very similar to the saw-toothed grain beetle, but 

lack the “sawtoothed” projections on the pronotum. 

Copra Beetle, Necrobia rufipes (Coleoptera: Cleridae) 

Though it is a predatory beetle with a cosmopolitan distribution. The insect feeds on 

molds on damp grain/ kernels and other farinaceous materials. In feeding on moldy grain, it 

may also damage the germ of the kernels if the relative humidity is over 65%. However, grain 

injury by this pest is not severe enough to cause economic damage. 

Tenebrionid/ Cadelle Beetle, Tenebroides mauritanicus (Coleoptera: Tenebrionidae) 

This beetle is cosmopolitan in distribution. It is found particularly in warehouses, silos 

and mills. The larvae is a pest of stored food feeding on grain, flour, meal, vegetables, dried 

fruits and other stored products. They feed on whole grains as well as processed grain 

products. The beetle is a predator of larvae of other grain-infesting insect pests such as the 

Indian meal moth and the saw-toothed grain beetle. 

Areca Nut Weevil/Coffee Bean Weevil, Araecerus fasciculatus (Coleoptera: Anthribidae) 

It infests stored products such as coffee, cocoa, nuts, maize and spices. A. fasciculatus 

is a small dome shaped beetle and is mottled dark brown with lighter brown patches. 

II. MOTHS 

Indian Meal Moth, Plodia interpunctella (Lepidoptera: Pyralidae) 

This is one of the commonest of dried fruit insects. This species is of worldwide 

distribution. In the field, it infests drying and dried raisins, waste fruits, and fruit refuse. 

Larvae feed first on the embryo or germ of the kernels and while eating spins a silken thread 

on which the droppings of the larvae accumulate. Often these larvae feed close together and 

give the impression of living in colonies with infestation first being observed due to the 

presence of several silken lumps to which granules of the produce adhere. The youngest 

larvae can enter very fine crevices, unexpectedly infesting commodities in containers thought 

to be insect proof. 

Almond Moth/ Tropical Warehouse Moth, Ephestia cautella (Lepidoptera: Pyralidae) 

This moth is abundant in tropical regions on a wide range of food stuffs and also 

encountered in sub-tropical and temperate regions. The larvae attack drying and dried fruits. 

Fruits are attacked until they become too dry. Only germs are eaten by the larvae leaving 

the kernel undamaged. In heavy infestation, larvae cover all available surfaces with webbing. 

In bulk storage, damage is confined to surface but in bagged storage it is widespread. 

Rice Moth, Corcyra cephalonica (Lepidoptera : Galleriidae) 

The larva feeds on parts of the kernels/ dry fruits by boring inside. Larvae produce dense 

webbing and in such cases kernels are bound into lumps. Infestation is characterised by the 

presence of silken lumps to which grains adhere. 

107

109 

Table 2. Insect-pests associated with important dry fruits in India 

Order Family Common Name Scientific Name Dried fruit Citation 

Coleoptera Anobiidae Tobacco beetle/ Lasioderma serricorne Fabr. Cashew, Copra, Walnut Gill et al. (1975), 

Cigarette beetle Singh (1988), 

Kumari et al. (1992), 

Khare (1993) 

Anthribidae Areca nut weevil/ Araecerus fasciculatus Degeer Copra Kumari et al. (1992) 

Coffee bean weevil 

Bostrychidae Lesser grain borer Rhyzopertha dominica (Fabr.) Various dry fruits Ghosh and Durbey (2003) 

Cleridae Copra beetle/Red ham Necrobia rufipes (Fabr.) Cashew, Copra Singh (1988), 

beetle Kumari et al. (1992) 

Curculionidae Rice weevil Sitophilus oryzae L. Cashew Singh (1988) 

Dermestidae Khapra beetle Trogoderma granarium Everts Cashew, Walnut Singh (1988), 

Gill et al. (1975) 

Nitidulidae Corn sap beetle Carpophilus dimidiatus (Fabr.) Copra Kumari et al. (1992) 

Silvanidae Foreign grain beetle Ahasverus advena (Waltl) Copra Kumari et al. (1992) 

Merchant grain beetle Oryzaephilus Mercator Fauv. Cashew, Copra, Pistachio Rad et al. (1997) 

Saw toothed grain beetle O. surinamensis Linn. Cashew, Copra, Gill et al. (1975), 

Date Pam, Walnut Singh (1988), 

Kumari et al. (1992), 

Ghosh, Khare (1993), 

Ghosh and Durbey (2003), 

Mohandes (2010) 

Tenebrionidae Tenebrionid/ Cadelle beetle Tenebroides mauritanicus Linn. Walnut Gill et al. (1975) 

Confused flour beetle Tribolium confusum Sac. Date Palm Ghosh and Durbey (2003), 

Mohandes (2010) 

Rust Red flour beetle T. castaneum Herb Cashew, Copra, Walnut Gill et al. (1975), 

Singh (1988), 

Kumari et al. (1992) 

Lepidoptera Galleriidae Rice moth Corcyra cephalonica Stainton Cashew Singh (1988), 

Khare (1993), 

Ghosh and Durbey (2003) 

Gelechiidae Angoumois grain moth Sitotroga cerealella (Oliver) Cashew Singh (1988) 

Pyralidae Almond moth/ Tropical Ephestia (Cadra) cautella Almond, Copra, Khare (1993), 

warehouse moth Walker Pistachio, Raisin, Walnut Kumari et al. (1992), 

Gill et al. (1975) 

Indian meal moth Plodia interpunctella Hubner Various dry fruits Khare (1993), 

Ghosh and Durbey (2003), 

Bhargava et al. (2007) 

Pine cone (chilgoza) borer Dioryctria abietella (Denis & Schiff.) Pine nut (chilgoza) Thakur (2000)

Angoumois Grain Moth/Grain moth, Sitotroga cerealella (Gelechiidae: Lepidoptera) 

This pest was first reported in 1736 from the Angoumois province of France. But now it is 

distributed throughout the world including India. Only larvae are damaging. The tiny larva 

crawls about a little for finding out a soft spot through which it enters the kernal. When it is 

inside, closes the entry hole by a silken web and develops therein. The kernels are hollowed 

out and filled with their excreta and webbing. It attacks both in fields and stores. In bulk 

storage, infestation remains confined to upper 30 cm depth only. Caterpillar enters the kernal 

through cracks or abrasions and feeds inside. 

Pine cone (Chilgoza) borer, Dioryctria abiete la (Lepidoptera: Pyralidae) 

The insect is responsible for causing economic damage to cones and seeds of various 

coniferous species including Pinus gerardiana. In nature, the larvae of D. abietella from third 

stage onward damage the cones and seeds of conifers while the preceding instar larvae feed 

on soft tissues of the cone. The last stage larvae feed voraciously on both the green and old 

cones in field, and cones and seed under storage. 

Assessment of Losses by Dry Fruit Insect-Pests 

Losses caused by insects in dried fruits are difficult to estimate. The loss of weight from 

insect feeding is usually trivial. The most serious loss is in appearance and quality, which 

lowers or destroys market value. Also, the presence of insects or any other foreign material 

in dried fruit is objectionable to consumers. 


Bhargava, M.C., Choudhary, R.K. and Jain, P.C. 2007. Advances in management of stored 

grain pests. In : Entomology: Novel Approaches. P.C. Jain and M.C. Bhargava (eds). 

pp. 425-451. New India Publishing Agency, New Delhi. 533p. 

Ghosh, S.K. and Durbey, S.L. 2003. Integrated Management of Stored Grain Pests. 

International Book Distributing Company, Lucknow. 263 p. 

Gill, J.S., Srinath, D. and Gupta, T.C. 1975. Preliminary survey of insect infestation in stored 

walnut (Juglans regia, L.). Plant Protection Bulletin India 23 (4) : 30-33. 

Khare, B.P. 1993. Stored Grain Pests and their Management. Kalyani Publishers, New Delhi. 

314 p. 

Kumari, T.N., Mammen, K.V. and Mohandasb, N. 1992. Occurrence and nature of damage 

caused by pests of stored copra in Kerala. Indian Coconut Journal, Cochin 23 (7) : 7-12. 

Mohandes, EI M.A. 2010. Methyl bromide alternatives for dates disinfestations. Acta 

Horticulturae 882 : 555-562. 

Rad, S.P., Pajni, H.R. and Neelima Talwar. 1997. Status of Oryzaephilus mercator (Fauvel) 

(Coleoptera: Cucujidae) as a pest of common dry fruits. Entomologist 116 (3/4) : 239- 

244. 

Singh, V. 1988. Serious pests of stored cashew kernels. Journal of Plantation Crops 16 (2) 

: 133-137. 

Thakur, M.C. 2000. Forest Entomology (Ecology and Management). Sai Publishers, Dehradun. 

609 p. 

109

DIAGNOSTIC SYMPTOMS AND ASSESSMENT 

OF LOSSES DUE TO INSECT- PESTS IN 

TEMPERATE FRUIT CROPS 

P. K. Mehta and R. S. Chandel 



Temperate fruits like apple, almond, peach, plum, apricot, cherry walnut, pear etc. are 

grown on large area in wet temperate zone and these fruits have uplifted the economy of 

farmers to a great extent. During recent past the productivity of apple and other temperate 

fruits has gone down. With the cultivation of fruit crops on large areas the incidence of 

insect pests has also increased in recent years. Attack by different insect pests has 

contributed significantly in declining the productivity of these fruit crops. Over 1000 species 

of insects have been reported to occur on fruits through out the world. About one and a half 

dozen of them are considered major pests of temperate fruits and are discussed in the 

forgoing text. 

1. Sanjose scale, Quadraspidiotus perniciosus (Comstock) : 

It is a serious pest of apple and pear. The damage is caused by nymphs and adults 

which suck the cell sap from twigs, branches, spurs and fruits. Heavily infested branches 

appear as if they are sprinkled with ash and ultimately dry up. On fruits small reddish round 

specks appear especially on the calyx end due to sucking of cell sap. The quality of such 

fruits gets deteriorated and market value is reduced greatly. The crawlers emerge during 

spring, crawls for few hours and after getting a suitable place settles down and remains 

there through out the life under a protective covering excreted by itself. In lower hills there 

are five generations and in higher hills only three generations are completed in a year. 

2. Apple woolly aphid, Eriosoma lanigerum (Housmen) : 

This insect is a major pest of apple and pear and is distributed in all apple growing parts 

of India. It lives in colonies in the form of white cottony patches on stems, branches and 

roots. It sucks the plant sap and results in the formation of galls on stems and roots. The 

galls formed on roots are bigger in size and acts as sink in translocation of food material 

from either side. The insect migrates from roots to above ground parts and vice versa 

throughout the year. The pest is more active during March to September and multiplies and 

develops at a reduced rate during October to February. The aphid reproduces 

parthenogenetically and the progeny thus obtained consists of females only. There are four 

nymphal instars and their duration varies according to season. The affected plants remain 

stunted and yield poor quality fruits. 

3. Blossom thrips : 

This pest is serious during hot and dry weather during spring. Both young ones and adults 

cause the damage by rasping the cell sap from flowers, leaf axils and tender leaves. The attacked 

flowers gets deformed and do not open as a result of which the fruit set is reduces. 

4. Apple root borer, Dorysthenus hugelii Redtenbacher : 

It is serious pest of almost all the temperate fruits. The attack is more in orchards 

having sandy soils and planted on sunny aspects. Red chest nut coloured big sized beetles 

appear with the onset of monsoon and females lay eggs in soil from June end to August 

110

which hatch in about 20-30 days. Grubs on hatching feed on organic matter, fine roots and 

later on shift to the main roots and continue to feed on roots for about 3 –3½ years. Grubs 

nibble the roots and cut them into two peices just near the collar region. Full grown grub is 

10 cm long. After the grub is full fed it makes an earthern celll and pupates inside. Pupal 

period lasts for about 6 months and the total life cycle is completed in about 4 years. The 

affected trees loose their hold in the soil and get uprooted in strong winds. Above ground 

plant parts exhibit sickly appearance and yellowing and withering of leaves on one side of 

the tree. Since the life cycle of the pest is long even one or two grubs are sufficient to kill 

the full grown plant in about four years. 

5. Leopard moth, Zeuzera multistrigata Moore : 

It is a serious pest of temperate fruits like cherry, apple, plum peach, walnut etc. Eggs 

are laid during July- August on stems and main trunk. Larvae on hatching feed underneath 

the bark in early stages and later on tunnels into the branches or tree trunk and feed on sap 

wood. The affected trees show yellowing of leaves followed by drying of terminal branches 

extending down wards. The larval stage lasts for about 20-22 months and total life cycle is 

completed in 25-26 months. 

6. Stem borer, Aelosthes holeserica : 

It is a serious pest of apple, cherry, apricot, peach, plum, pear, walnut etc. Beetles 

which are dark brown and 4-4.5 cm long with yellowish pubescence on the elytra are active 

during rainy season and lay white elliptical eggs which are 2.5 mm long on the branches and 

main trunk of the tree by making a cut in the bark. The eggs are also laid in the cracks on 

the branches. Grubs after hatching from the eggs (in 7-12 days) bore, into the stem/branches 

and brown pallets mixed with excreta can be seen adhering on the bark near the entry hole 

and lying on the ground. Symptoms produced on leaves are same as that of leopard moth. 

The larval period is completed in 27-32 months and pupal period in 40-100 days and the 

whole life cycle is completed in about three years. 

7. Phytophagous mites : 

There are two species of mites which are serious on apple. 

a) European red mite, Panonychus ulmi (Coach) : It is a serious pest of apple in 

Himachal Pradesh. Besides, it also attacks pear, plum, peach, cherry, almond, walnut 

etc. The mites are red in colour and very small in size and can hardly be seen with 

naked eye but can easily be seen with the help of hand lens. Mites suck the cell sap 

from under side of the leaves and eat away the chlorophyll. On attacked leaves, 

small light specks appear which overlap each other as the attack advances. Later on 

heavily infested leaves turn bronzy and cupping (folding from the margins) takes 

place. As the mite feeds on chlorophyll the photosynthesis is greatly hampered. 

Transpiration rate is also higher as a result the leaves dry up and fall pre maturely. 

Fruits remain small in size with fewer sugars. On the under side of the leaves white 

exuviae of mites can be seen. The attack is more during drought situation. Low 

temperature and high humidity adversely affects the reproduction and development 

of the pest. During winter, mite remains in egg stage. Clusters of eggs which are red 

in colour can be seen at the base of spurs, cracks and crevices in the stem during 

winter. These eggs hatch during spring and larvae, start attacking the leaves and 

subsequently develop into protonymphs, deutonymps and the adults. It takes about 

one month to complete the life cycle from egg to adult. During active season the 

eggs are laid on the under side of the leave near the mid rib or side ribs and 5-6 

111

generation are completed in a year before the winter eggs are laid during September 

– October which over winters. 

b) Two spotted mite, Tetranychus urticae Coach : This mite is also called as red 

spider mite. The adult mite is deep yellow coloured with two black spots on the 

back. Adult mites over winter in fallen dry leaves, grasses in the orchard, cracks and 

crevices in the tree trunk. During spring, when temperature rises, these mites crawl 

on to the tree and starts sucking the cell sap from the leaves. Life cycle is completed 

in 10-30 days and 8-15 generation are completed in a year. This mite spins a web 

and move from one leaf to other with the help of these webs. Symptoms on leaves 

are similar to that of European red mite. 

8. Defoliating and fruit eating beetles : 

Large number of species of scarabaeid beetles are found attacking allmost all the 

temperate fruits. The most common are Brahmina coriacea (Hope), Anomala dimidiata (Hope), 

A. rufiventris Redten backer, A. flavipes Arrow, A. lineatepennis Blanchard etc. These beetles 

appear with the pre monsoon showers and remain active through out July- August. Beetles 

feed on leaves of temperate fruits and many forest plants. Besides defoliating the plants 

these beetles also feed on developing fruits of many temperate fruits. Beetles lay eggs in 

soil and the larvae commonly known is white grubs are pests of under ground crops like 

potato and also feed on roots of temperate fruits forest plants, weeds, grasses and humus. 

After the larva is full fed it makes an earthern shell and pupates in it. Only one generation is 

completed in a year. 

9. Apple leaf roller, Archips pomivora Meyrick : 

The pest is active from May to September. The caterpillars are green in colour with black 

head and feed on tender foliage by folding and biding two or more leaves together. Caterpillars 

also damage the fruit by scrapping the skin during August – September on the tree and also 

in storage. 

Management : Spray of carbaryl 0.05 per cent during June and malathion 0.05 per cent 

before harvesting (3 weeks before harvesting) reduces the incidence of pest. 

10. Indian gypsy moth, Lymantria obfuscata Walker : 

It is a pest of temperate fruits and deciduous forest trees. The adult moths are dull in 

colour and medium in size. Female moth lays eggs in cracks and crevices of bark, logs, 

stores and stones on the ground during June-July. The eggs are covered with yellowish 

brown scales. Caterpillars are nocturnal in habit and remain hidden during day time under 

soil, clods, and stones or in cracks and crevices. Larval period lasts for about 2-3 months 

and pupal period in 10-20 days. Only one generation is completed in a year and insect 

passes the winter in egg stage. 

11. Tent hairy caterpillar, Malacosoma indica Walker : 

This insect is an important pest of apple in some areas of Himachal Pradesh. Besides, 

it also attacks pear, apricot, walnut and forest trees. The caterpillars feed gregariously on 

foliage, leaving behind only the mid rib and other harder veins. Larvae spin silken nests 

which appear like tents on the tree and remain hidden in these tents during day time. During 

night the caterpillars are active and feed on leaves. Larval period lasts for 40-70 days. Full 

grown larva spins on oval, white and compact cocoon for pupation. Pupal period is of 8-22 

days. Only one generation is completed in a year. 

112

12. Apple fruit moth, Argyresthia conjugella Zeller : 

It is a serious pest of apple in dry temperate zone of Himachal Pradesh. Adults emerge 

from overwintering pupae during May- June and lay eggs singly on the surface of the fruits 

which continues for about a month. Larva after hatching from egg bore into the fruit and feed 

on the developing seeds. Larval period is completed in about three weeks. Larva leaves the 

fruit before pupation and there is only one generation in a year. 

Management : Spray fenitrothirm 0.05 per cent or fenthion 0.04 per cent immediately 

after the incidence is noticed. Treatment of local varieties along with commercial varieties is 

important to check the multiplication of the pest on these varieties. 

13. Flat headed borer, Sphenoptera lafertei Thomson : 

It is a serious pest of cherry and peach but attacks other temperate fruit also. The 

adults are active during March- April and lay small, spherical, white eggs on the stem bark. 

The grubs on emergence bore into the bark and feed below the bark by making irregular 

interconnected galleries. Gum globules can be seen oozing out of the entrance hole. The 

damage in restricted to the pant parts exposed to the sun light. The larval period is completed 

in 2 months during summer and 6 months during winter. 

14. Shot hole borer, Scolytoplatypus raja Blandaf : 

It is a pest of poorly managed, sick and weak plants. The beetles make pinholes in the 

sapwood and lay eggs. Grubs feed on sap wood by making vertical galleries. The flow of 

plant sap is affected and plant dries due to wilting. 

15. Peach leaf curling aphid, Brachycaudus helichrysi Kaltenbach : 

It is a serious pest of peach but also attacks other temperate fruits like plum, apricot, 

almond etc. Aphids suck the cell sap from leaf axils and tender leaves which results in 

curling of leaves. Curled leaves become brittle due to lack of cell sap. Infected plants bear 

small fruits and the market value of such fruit is reduced. Pest is heterocyclic and passes 

summer and rainy season on alternate hosts like golden rod, Erageron canadensis, Trifolium 

pratense, Cineraria sp. in higher hills and Ageratum conyzoides in the lower hills. Winter, 

spring and a part of summer are passed on primary hosts. Eggs hatch during January to 

March depending upon the altitude and the nymphs start sucking cell sap from developing 

leaves. These nymphs develop into wing less females which reproduce parthenogenetically 

and 3-8 generations are completed on the fruit trees. With the warming up of the season, 

winged male and females are produced which then migrate to the alternate hosts. Four to 

five generations are completed on alternate hosts form June to October. During October – 

November again the winged forms develop which migrate back to primary hosts and lay eggs 

on the base of the buds and spurs. After egg laying, females die and eggs over winter. 

16. Peach fruitfly, Bactrocera zonatus (Saunders) : 

This pest causes heavy losses to peach. The damage is caused by the maggots only 

and the attack is characterized by the dark punctures, oozing of fluid, rotting and dropping 

of fruits. The maggots are creamy white, head less and legless. Female fly lays eggs inside 

the fruit by injecting its ovipositor into the fruit. The eggs hatch in 2-4 days during May-July 

and the maggots feed on the fruit pulp by making galleries. Larvae are full fed in 5-15 days. 

Fruits along with larvae fall on the ground and the full fed larvae comes out of fruit and 

pupate in soil. Many generations are completed in a year. 

113

17. Walnut weevil, Alcidodes porrectirostris Marshal : 

It is a serious pest of walnut in the himalayan region. Adult weevils are active from April 

onwards and lay eggs inside the developing fruits. Grubs on hatching bore deeper into the 

fruits and feed on the kernels. Grub becomes full fed in 13-22 days and pupates inside the 

fruits. The adults emerge from fruits by biting a round hole. These weevils start second 

generations and the adults from second generation are formed during September – October 

which over-winters in plant debris, stones, cracks and crevice in ground and bark of trees. 

Adult weevils feed on flowers, leaf buds, tender shoots and young fruits. 


Bhalla, O.P. and Gupta, P.R. 1993. Insect pests of temperate fruits. In: Advances in 

Horticulture, Fruit Crops, Part 3 (Eds. K.L Chadda and O.P. Pareek) Malhotra Publishing 

House, New Delhi: 1557-1589. 

Choudhary, M.L.; Awasthi, R.P.; Gupta, V.K.; Roy, S.K.; Gautam, D.R.; Sikka,B.K. and 

Samuel, J.C. 2005. Orchard Management in Apple: A Training Manual. National Project 

Director, FAO Apple Project, Ministry of Agriculture, New Delhi: 150 p. 

Gupta, D. 2010. Insect pest management in temperate fruits. In: Plant Protection Practices 

in Organic Farming. (Eds. Ajay Sharma and R.S. Chandel), International Book 

Distributors, Dehradun: 191-213. 

Gupta, P.R. 2005. Advances in integrated pest management of pome fruits. In : Advances in 

the Integrated Pest Management of Horticultural, Spice and Plantation Crops (Eds. B.S. 

Chhillar, V.K. Kalra, S.S. Sharma and Ram Singh ). Centre of Advanced Studies, 

Department of Entomology, CCSHAU Hissar: 43-49. 

Sharma, J.P. and Thakur J.R. 2004. Insect and mite pests of apple and pear. In: Pest 

Management in Horticulture Crops (Eds. LR Verma, D.C. Gautam and A.K. Verma). 

Asiatech Publishers, Inc New Delhi: 237-258. 

114

DIAGNOSTIC SYMPTOMS AND LOSS ASSESSMENT DUE 

TO MITE PESTS IN IMPORTANT CROPS 

Rachna Gulati 

Department of Zoology 


Symptoms and assessment of crop losses due to pest damage is necessary for the 

development and testing of pest control strategies. In addition, loss assessment is used by 

field functionaries/ farmers choosing among alternative control strategies, and economic 

damage thresholds are often used when making decisions about implementation of these 

strategies. Among the arachnids, Acari are the only group, which feeds on plants. 

Crop wise status of major and minor mite pests in India is provided in tabular form for 

ready reference (Table 1). Details of the diagnostic symptoms and losses caused by different 

families are given under separate headings, although it may be mentioned here that for loss 

assessment, correct sampling procedures are needed. 

Tetranychidae : Spider mites are one of the major pests of vegetable, ornamental and 

fruit crops, causing considerable loss in yield. The loss is however related to the population 

level and stage of infestation. These mites are soft bodied, variously coloured, colony forming 

and many of these can spin webs to protect themselves from natural enemies and pesticides. 


Both nymphs and adults feed on the leaf surface. White specks are formed on the leaves 

in later stages of infestation and general chlorosis occurs in patches. Small rounded chlorotic 

spots are formed as mites punctures new cells of one spot to another in the form of a circle. 

In leaves damaged by mites, degeneration of chloroplast structure, reduction in stomatal 

(day time) transpiration and increase in cuticular (night time) transpiration occur thereby 

reducing leaf gas exchange and inhibition of photosynthesis. Thus, in case of severe 

infestation, plants show yellowing and general drying of leaves, which drop prematurely. 

There is extensive webbing on leaf surface and black faecal dots are seen on the leaf surface. 

Severe spider mite infestation cause major reductions in plant growth rates, flower formation 

and yield. All developing stages of mite suck the cell sap from host plants. Its persistent 

infestation deprived of chlorophyll of leaves, hampers the photosynthesis; causes stippling 

and formation of scars and blotches on leaves. In case of severe infestation, serious defoliation 

occurs. 

Damage symptoms peculiar to particular species is provided below to understand their 

behaviour. 

Tetranychus and Schizotetranychus sp. prefer lower leaf surface. 

Eutertanychus and Oligonychus sp. prefer upper leaf surface. 

T. urticae- chlorotic patches on leaves which turn brownish and drop off. Blackening of 

leaves, decrease in fruit size and yield is observed in pear. 

T. ludeni- yellow-bronze leaves in beans. In mulberry, white specks are formed which are 

enlarged to form large patches and give rusty, dry look. It is also a vector of Dolichos Enation 

Mosaic Virus. 

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E. orientalis- infestation starts along the midrib and later spread to lateral veins; chlorotic 

patches also appeared due to feeding. 

E.hirsti- trasparent green patches on the leaves’ under surface are observed initially 

which turn yellowish green, brown with rough and dry texture. 

O. coffeae- infested leaves turn brown and dry up. 

S. andropogoni- white patches on sugarcane leaves are observed which turn brown and 

dry. 

Panonychus citri- stippling and light coloured spots on foliage which give greyish or 

silvery appearance. 

P. ulmi- normally found on upper surface of foliage, heavy infestation leads to reduction 

in fruit size and yield. 

Petrobia latens- leaves dry up from tip downwards, start showing yellowing appearance 

which ultimately dry out. Heavily infested plant gives sickly appearance. 

Losses due to spider mite infestation 

In various crops, 10-15 per cent losses are reported due to spider mites and in some 

cases, total loss is reported. In particular, 50-80 per cent in mango 10-15 per cent in rice, 

15-20 per cent in tea, 10-25 per cent in sugarcane, 13-31 per cent in brinjal, 25 per cent in 

okra due to spider mites are reported (Table 2). Loss assessment due to Eutetranychus 

orientalis infestation in forest tree species, Azadirachta indica, Albizia lebbeck, Moringa 

oleifera, Ailanthus excelsa and Zizyphus jujuba, showed that it greatly affected the growth 

attributes of seedlings (Mohammad et al., 2006). 

Eriophyidae : These are often referred to as ‘‘adventive species’’ which means alien or 

exotic species/ subspecies, introduced into an area outside its native range and includes 

many species that cause ecological or economic problems throughout the world (Wheeler 

and Hoebeke, 2009). Eriophyoid mites representing 85 species and 30 genera are mentioned 

as invasive; genera with the higher number of invasive species include Aceria (29), Eriophyes 

(7), Aculops (5), Aculus (4), Acalitus (3), Phyllocoptes (3) and Trisetacus (3). They are 

considered efficient vectors of plant diseases caused by 21 pathogens with at least 26 

plant diseases are associated with eriophyid mites (Jones 1999). 


The mites occur on all parts of a plant and may or may not exhibit the symptoms of 

damage. Based on type of injury, they have been classified as under: gall formers (pouch 

galls (Pongamia sp.), bead galls (Ficus sp.), finger galls (Pongamia sp.), bud mites (feed on 

developing vegetative buds within unopened leaves), leaf rollers (roll the whole leaves or only 

edges of leaves and feed within the rolls), erineum formers (hair like out growths on leaves), 

blister mites (blisters on the leaf sheath and feed within) and Vagrants (found on both surfaces 

of leaves). Apart from these injuries, some species play a vital role in virus transmission like 

Pigeonpea Sterility Mosaic Disease by Aceria cajani, Wheat Streak Mosaic Disease by A. 

tulipae, Sugarcane Streak Mosaic Virus by A. sacchari, Fig Mosaic Virus by A. ficus etc. 

Damage symptoms peculiar to particular species is provided below to understand their 

behaviour. 

A. litchi -infestation leads to deformation, curling of leaves, chocolate brown erineum on 

leaf’s lower surface, leaves become dry and fall. 

116

A. lycopersici - curling of leaves, appearance of silver gloss on lower surface, roughened 

appearance on leaves of brinjal, tomato. There is loss of hair, change of colour and cracks 

appear in stems. 

A. mangiferae - mango malformation, suck sap from buds which cause necrosis of tender 

tissues. 

A.guerreronis - injury in floral tracts, injured area become shrivelled, brown and cracks 

appeared in fruits. 

A. cajani - diseased plant show dwarfing of leaves, bushy habitat, yellowish green leaves, 

complete suppression of flowering and fruits. 

A. jasmini- cause red blisters on the inner surface of leaves, malformed floral parts. 

A. sacchari - formation of blisters of various shapes on inner surface of sugarcane leaf 

sheath. The colours of blisters are green then rusty. 

E. sheldoni -lemon bud scales are blackened, multiple budding on infested twigs, 

abnormal floral parts. In orange, fruits are flattened vertically. 

P. oleivora-damaged fruits become silvery, reddish brown or purplish black, affected fruits 

have thicker skin and show rust spots. 

Acaphylla theae- veins and margins show pinkish discolouration, infested leaves are 

pale and leathery. 

Calacarus carinatus- infested leaves are initially in copperish brown colour, which turns 

purplish bronze. 

Cisaberoptus kenyae- white silvery coating on upper surface of leaves under which mites 

live. 

Losses due to Eriophyid mite infestation 

In coconut, colonies of mites are established under the bracts, where they cause necrosis 

on the lower surface of the bracts and on the adjacent surface of the fruits, which are often 

aborted (Nair 2002). Even when not aborted, the injured fruits commonly show reduced weight, 

size, volume of coconut water and albumen. Yield losses can reach over 60% (Moore 2000). 

In other crops, deformity to plants or its parts caused complete suppression of flowering and 

fruit formation in case of severe infestation. 

Tenuipalpidae : These false spider mites resemble tetranychid mites but they cannot 

spin webs. These colony-forming mites who generally feed on lower surface of leaves, near 

the midrib or veins. Brevipalpus sp. is a vector of many viruses. Brevipalpus transmitted 

viruses (BrTVs) are considered putative members of the Rhabdoviridae family because of 

their short, rod-like or bacilliform particles, and their ability to accumulate and induce 

cytopathological effects either in the cytoplasm or in the nucleus of infected cells. 


Bronzing and rusting symptoms are caused on the lower surface of leaves due to feeding 

of nymphs and adults. Some species form galls on the leaves and stems of plants while 

others feed on bark of trees, leaf sheaths and floral heads. Each species has peculiar damage 

symptoms in host plant, which is provided here for better understanding of their behaviour. 

Raoiella indica- showed reddish spots on leaves. 

117

B. californicus- infested leaves produce brownish patches. 

B. phoenicis- infested leaves turned pale yellow and develop brownish patches. 

B. obovatus- produced chlorotic patches with concentric rings of reddish resinous material. 

D. floridanus- feeding is at basal parts of leaves which cause rust like symptoms. 

L. transitans- mites form galls on ber. 

Tarsonemidae : This family includes phytophagous, fungivorous and parasitic mites of 

scale insects and honeybees. These mites are very small in size varying from 100-300 m in 

length. Body is soft, round, oval, white and glossy in colour. These are fast moving mites. 


They usually infest the tender portion of plants and suck the sap from buds, leaves, 

shoots, flowers and stem sheath. They cause curling, crinkling and brittleness of foliage but 

shows little leaf symptoms. The injury caused by this group is often mistaken as a disease 

symptoms caused by pathogenic microorganisms. Damage symptoms of the common genera 

are given below in different host plants. 

S. spinski- increase in percentage of empty grains. They carry spores of rice sheath rot 

fungus, which causes brown spots on rice sheath and grains. This disease is known as 

‘Sterile grain Syndrome’ 

S. bancrofti- internodes give scabby corroded appearance, transparent depressions on 

young stalks. 

P. latus- In chillies, leaving curling is a common symptom associated with this mite. In 

citrus, there is bronzing, roughening and crinkling of leaves. In potatoes, oily blackish spots 

appear on the under surface of young leaves which turn reddish. H. latus- leaf remain smaller 

in size, crumpled leaves are observed which turn brownish. 

Losses due to Tarsonemid mite infestation 

Polyphagotarsonemus latus has attained a pest attained in crops. It is reported to cause 

27-39 per cent losses in chillies. It feeds on lower surface of leaves causing leaves to 

become rigid and curled, prevents flower and fruit development. This disease is termed as 

‘Murda disease’. In potatoes, due to its infestation the plant wither from the tip and auxillary 

buds are killed. This disease is known as ‘Tambera disease’. 

Acaridae : Mites in the family Acaridae are among the most important acarine pests 

attacking agricultural and stored product systems. Within this family, bulb mites of the 

genus Rhizoglyphus are economically important pests of plants with bulbs, corms, and 

tubers. The two most common species, Rhizoglyphus echinopus and Rhizoglyphus robini, 

are probably cosmopolitan and damage a variety of crops including onions, garlic, other 

Allium species, Lili, Hyacinth, and many other vegetables (carrots and potatoes etc.), cereals 

(rice, rye, wheat, barley, oats etc.), and ornamentals (Gladiolus etc.) in storage, in the 

greenhouse and in the field. 

Rye, barley and oats plants used as cover crops and windbreaks, a factor that may 

contribute to their persistence and outbreaks. 

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Table 1. Crop wise Status of Major and Minor Mite Pests in India 

Crops Major pest Minor pest 

Vegetables 4 2 

All vegetables Tetranychus urticae 

Brinjal T. neocaledonicus T. macfarlanei 

Cowpea T. ludeni 

Chilli, potato, tomato Polyphagotarsonemus latus 

Cucurbits T. macfarlanei 

Fruit trees 6 18 

Apple T. urticae, Panonychus ulmi 

Citrus Eutetranychus orientalis, Schizotetranychus hindustanicus, 

Brevipalpus phoenicis Panonychus citri, Brevipalpus californicus, 

Phyllocoptruta oleivora 

Guava, Pear B. phoenicis C. kenyae 

Mango Aceria mangiferae Oligonychus mangiferus 

Litchi A. litchii O. mangiferus, O. beharensis 

Fig A. ficus, Eotetranychus hirsti 

Pear O. obovatus 

Banana O. indicus 

Pomegranate O. punicae 

Grapevines O. mangiferus 

Loquat O. beharensis 

Ber Larvacarus transitans, Eriophyes cernuus 

Date palm Raoiella indica 

Cereals 1 4 

Wheat Petrobia latens 

Paddy O. indicus, O. oryzae, S. andropogoni, 

S. spinki 

Pulses 1 3 

Red gram A. cajani S. cajani 

Black gram, green gram T. urticae, P. latus 

Oilseeds 2 1 

Castor, soybean T. urticae 

Coconut A. guerreronis R. indica 

Ornamentals 3 4 

Rose T. urticae E.orientalis,B. phoenicis 

Zinia T. neocaledonicus 

Marigold P. latus B. californicus 

Jasmine A. jasmini 

Fibre crops 2 1 

Jute P. latus 

cotton T. urticae T. macfarlanei 

Plantation crops 5 4 

Tea O. coffeae, B. phoenicis, T. urticae, B. obovatus 

P. latus, Acaphylla theae, 

Calacarus carinatus 

Arecanut O. indicus, R. indica 

Commercial crops 1 3 

Sugarcane O. indicus A. sacchari, S. andropogoni, S. bancrofti 

Fodder crops 1 1 

Sorghum O. indicus 

Grasses S. andropogoni 

Spices 1 3 

Chilli P. latus 

Coriander P. latens 

Cardamon B. phoenicis, Dolichotetranychus floridanus 

Shade trees 1 1 

Neem E. orientalis 

Saal O. beharensis 

119

Table 2. Yield losses due to Different Phytophagous Mites 

Mite species Crop Losses (%) 

Spider mites Vegetables 10-15 

T.urticae Okra 23-25 

Brinjal 13-31 

Cotton 20-30 

Pointed gourd 36 

T. macfarlanei Brinjal 12.18 to 32.21 

O. coffeae Tea 5-11 

S. andropogoni Sugarcane 20-30 

O. indicus Sorghum 56 

O. oryzae Paddy 20-25 

P. latus Chillies 27-39 

L. transitans Ber 20-40 

A. litchii Litchi 30 

A. mangiferae Mango 50-80 

A. cajani Pigeon pea 15-30 


Bulb mites attack the roots and other subterranean structures of plants, but are also 

occasionally collected on the leaves and stems of infested Liliaceae. Seeds of a variety of 

crops are also affected. R. costarricensis attacks the seeds of O. sativa, and mites are 

often found protected inside the seed coat (Bonilla et al., 1990). Similar behavior has been 

observed on R. robini attacking barley, oats and rye. Infestations of corms and bulbs are 

characterized by penetration through the basal plate or outer skin layer and subsequent 

establishment in the inner layers. Condition of bulbs and corms may affect rates of colonization 

and establishment. Damaged and cull onions are often colonized by bulb mites, a factor 

that may contribute to mite outbreaks during the following growing season. 

Loss caused due to acarid mite infestation 

Little data are available on loss assessment due to Rhizoglyphus spp. infestations. 

Rawlins (1955) stated that yield from onions infested with R. robini was reduced sharply in 

infested areas, but provided no quantitative estimates of losses. Wang (1983) observed 

losses that ranged between 54.2% to 90% on Gladiolus infected with R. robini in China. 

Nakao (1991) observed 30% damage due to R. robini on Welsh onion (Allium fistulosum) 

seedlings grown in the greenhouse. 


Kubo, K. S.; Novelli, V. M.; Bastianel, M. Locali-Fabris E. C.; Antonioli-Luizon R. Machado 

M. A. and Freitas-Astu´a J. 2011. Detection of Brevipalpus-transmitted viruses in their 

mite vectors by RT–PCR. Exp Appl Acarol 54 : 33–39. 

Moore, D. 2000. Non-chemical control of Aceria guerreronis on coconuts. Biocontrol News 

Infor. 21 : 83–87. 

120

PREDICTING INSECT POPULATIONS USING MODELS 

Ram Niwas and M. L. Khichar 

Department of Agricultural Meteorology 


Models are representations of complex phenomena and are used to understand and 

predict changes in those phenomena. Population dynamics of various organisms, specially 

insects, are of particular concern as population changes affect human health, production of 

ecosystem commodities and the quality of terrestrial and aquatic ecosystem. Hence, 

modeling improves our ability to understand and predict changes in insect population 

abundances and has a rich history. 

The act of developing relationship between pest development and its environment using 

mathematical equations is called pest modeling. 

Model : It is an equation or set of equations which represent the behavior of a system. 

In simple terms, a model is a mathematical representation of a system and it acts as mimicry. 

Model is a mean of understanding the concept. It is simplification of reality. 

Pest model : A mathematical or at least computer based representation of pest 

population, its development and mortality processes. A model may also include a pest’s 

relationship with the crop or livestock host and processes involved in its control. 

Pest-weather model : A simplified representation of the relationships between weather/ 

physical environment on one hand and growth, development and multiplication on the other 

hand. 

Importance of Modelling 

1. Models represent explicit hypothesis of how key component and process affect pest 

population development, crop damage or the effectiveness of control. 

2. Prediction of pest attack and extrapolation from one situation to another. 

3. Operational tools for rear time guidance to pest control decision making. 

4. Model can assist the process of improving pest management. 

Types of insect pest models 

The pest-weather models can be grouped into three main categories. 

1. Statistical model : 

In this type of model, one or several environmental variables are related to insect/pest 

growth and development. There are two types of variables. One is independent and other is 

dependent. The independent variables are meteorological, derived agrometeorological and 

other environmental variables, etc. The dependent variable is the insect/pest parameter such 

as its growth, development and multiplication. The statistical model does not lead to an 

explanations of the cause and effect relationships. It is very practical approach. It is very 

simple and easy to use. It requires minimum input data. Statistical model can be divided 

into three types : 

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1.1 Simple linear regression model 

The linear regression model with one independent variable as input parameter is 

termed as simple linear regression model. This model is expressed by the equation. 

y = a + bx 

Where, 

y = Dependent variable e.g. pest population 

a = Intercept or constant 

b = Slope or regression coefficient 

x = Independent variable e.g. environmental variable. 

1.2 Curvilinear regression/polynomial model 

This model represent a curvilinear relationship between independent and dependent 

variable. It is expressed by the equation: 

y = a + bx + cx2 + …………… 

where, 

a = Constant, b & c = Slope for x and x2 x2 = Second power of independent variable ‘x’. 

1.3 Multiple regression model 

The regression model with more than one independent variables as input parameters 

is defined as multiple regression model. The model is represented by the equation: 

y = a+b x, + b x + b x + ……………. +bn xn 

1 2 2 3 3 

n 

y = a+ Σ bi xi 

i= 1 

where, 

a = Constant, bi = Partial regression coefficient for ith variable 

xi = Independent variables for i =1 to n 

Regression models provide estimates of the net effect for dependent variable ‘y’ 

based on the continuous operation of each in a set of independent variables (x , x 1 2 

…., xn). The relative influence of each x on y is measured by the respective partial 

regression coefficients (b , b ………., bn). Each of these b’s is a constant which 

1 2 

represents an average rate and functions continuously in the operation of the model. 

Thus, it is also called as holistic model. The limitation of the holistic model is their 

inability to account for the critical dependence of some events on the prior occurrence 

of the other events in a required sequence. 

2. Mathematical models 

2.1 Simple population models 

2.1.1 Exponential model: (Vanderplank, 1838) 

The population growth rate is directly proportional to the growth already present. The 

differential equation for this model is given by : 

dy 

---- = ry 

dt 

122

where, 

y = Size of population, r = Instaneous growth rate 

By integration we get 

y = y exp t o rt 

where, 

y =Population size at ‘t’ = 0 

o 

y = y + ry t+1 t t 

Where, 

y and y Population at‘t’ and‘t + 1’, respectively 

t+1 t = 

r = (N+I) – (M+E) 

Where, 

N = Natality, M = Mortality 

I = Immigration, E = Emmigration 

Where, 

Time specific natality, mortality and dispersal data have not been collected ‘r’ can be 

estimated as 

r = log R / T 

e 0 

Where, 

R = Replacement rate, T = Generation time 

0 

2.1.2 Logestic model: (Verhulust, 1988) 

No population could sustain such an increase for long. Without other constraints, 

competition for resources would become increasing severe and the net rate of increase dy/ 

dt would be reduced due to mortality, reduced fecundity or both. In this model the rate of 

growth is proportional to the product of present size (ry) and future amount of growth (k-y). 

This may be mathematically expressed as : 

dy/dt = ry(k-y)/k 

Where, 

k = Maximum population size that environment can sustain 

By integration we get 

k 

y = ............. 

t 

(1+be-rt ) 

where, 

b = Constant 

2.1.3 Gompertz model (Gompertz, 1825) 

The rate of population growth may be mathematically expressed as: 

dy/dt = (ry) ln(k/y) 

The population growth at a time ‘t’ by integration we get: 

y = k exp (-b exp t -rt ) 

The Gompertz curve is also S shaped like the logistic curve but it is not symmetrical 

about its point of inflection. 

123

2.1.4 Monomolecular model (Mitscherlich, 1909 and Richards, 1969) 

The rate of population growth at a time is directly proportional to the growth yet to be 

achieved. Mathematically may be expressed as : 

dy/dt = r(k-y) 

The population size of time ‘t’ by integration is given by : 

y = k(1-be t rt ) 

This function steadily rises from a point k(1-b) at t = 0 to the limiting value of k. 

2.1.5 Geometric model: 

For insect species with non overlapping generations, the population, growth is given by 

the equation: 

t y = R yo 

t o 

Where, 

y and y = Insect population at time ‘t’ and initial population, respectively. 

t o 

R = Replacement rate i.e. per capita increase from generation to next. 

o 

2.1.6 Complex models: 

General models such as logistic growth models are limited by several assumptions and 

do not predict the dynamics of real system accurately. ‘r’ and ‘k’ are assumed to be constant. 

Infact, they are affected by natality, mortality, dispersal and changing environmental 

conditions, including depletion by dense population. Modeling real populations of interest, 

then, requires development of more complex models with additional parameters that correct 

these short comings, some of which are described as follows. 

Nonlinear density-dependent processes and delayed feed back can be addressed by 

allowing ‘r’ to vary as follows: 

r = r – sy – T 

max t 

Where, 

r = Maximum per capita increase 

max 

s = Strength of interaction between individuals in the population 

T = Time delay in feed back 

The sign and magnitude of ‘s’ also can vary, depending upon the relative dominance of 

competitive interactions: 

s = s - s y p m t 

Where, 

s = Maximum benefit of competitive interactions. 

p 

s = Competitive effect with assumption that ‘s’ is a linear function of population density 

m 

at time ‘t’ (Berryman, 1981). 

The extinction threshold ‘E’ can be incorporated by adding a term forcing population 

change to be negative below this threshold: 

y = y – r y (k-y )/k (y -E)/E 

t + 1 t t t t 

124

2.1.6.1 Lotka-Volterra model for competing species: 

The Lotka-Volterra equation for the effect of species competing for the same resources: 

Y = y t + r y t (k -y t-áy t)/k 1(t + 1) 1 1 1 1 1 2 1 

Where, 

y t and y t = Population of two (1 & 2) species at time‘t’. 

1 2 

á = Competition coefficient that measures the per capita inhibitive effect of species 2 

and species 1. 

2.1.6.2 Lotka-Volterra model of predator-prey Interaction 

This model describes the interaction between prey species with a density y and its 

predator, with density P by the differential equation: 

dy/dt = ry[(k-y)/k]-c yP 1 

dp/d t= -dp+c yP 2 

Where, 

r= Prey’s instaneous rate of growth. 

d= Death rate of predators in the absence of prey 

c = Coefficient of attack 

1 

c = Conversion factor of prey into more predator individuals 

2 

2.1.6.3 Nicholson-Bailey model of parasitoid- Host interaction 

The equation for this model is expressed as: 

y = Y exp t+1 t –aPt 

P = cy [1-exp t+1 t -aPt ] 

Where, 

y = Host population, P = Parasitoid progeny 

C = Mean numbers of parasitoid progeny produced per host attacked. 

a = Rate of host increase per generation. 

2.2 Mathematical models for age structured population dynamics 

2.2.1 Deterministic models with age structure 

2.2.1.1 Von Foster Model: Von Forster proposed the following model for age structured 

population: 

dn (t,a) + dn (t, a) = - µ (t,a) n (t,a) 

dt da 

where, 

n (t,a) = Population density at time ‘t’ and age ‘a’ 

t&a = Chronological time and age 

ì (t,a) = Death rate of time ‘t’ and age ‘a’ 

125

2.2.1.2 Leslie model: This model is a derived discrete analogue model of the Von Foster 

model. The solution of the Von Foster model in discrete terms with “a/”t=1 is given by: 

Where, 

n (t+”t) = ni (t) si (t) 

ni(t) = Population density in ith age class at time ‘t’ = n(t, ai). 

si(t) = Survival ratio of ith age class at time ‘t’ = 1-ì i (t, ai), 

i = 0 to m 

2.2.2 Deterministic models for physiological parameters 

2.2.2.1 Generalized Von Foster model 

The Von Foster Model for population dynamics in terms of physiological age/ 

developmental index ‘x’ is given by: 

dn + d [v(ö (t), x) n (t, x)] = - ì (t,x) n(t,x) 

dt dx 

Where, 

v (ö (t),x) = Temperature (ö) dependent development rate of individual 

organisms at time ‘t’ and physiological age ‘x 

2.2.2.2 Generalized Laslie Model 

where, 

The Leslie model is generalized to take into account the physiological age ‘x’. 

n (t+ “ t, x i+1 ) = n(t, x i *) s* i (t) 

x * = Interpolated between x and x i i i+1 

s *= Survival ratio of ith physiological age ‘x’ at time ‘t’ 

i 

2.2.3 Stochastic development models 

2.2.3.1 Macroscopic model 

The dynamics of the population with deaths assuming stochastic process of change in 

development is given by: 

dn (t,x) d 

+ [v(t,x) n(t,x)] - 1 d 2 [k(t,x) n(t,x)] 

dt dx 2 dx 2 

= -ì (t,x) n(t,x) 

where, 

ì (t,x)=Death rate of individual of age ‘x’ at time ‘t’ 

k(t,x)= Variance of individual development of age ‘x’ at time ‘t’ 

2.2.3.2 Microscopic model 

We assume the development of an insect can be viewed as an accumulation of small 

development increments over time. For every small time interval, the developmental level 

126

changes by ‘“x’. The development process of the ith individual organism for the time interval 

(t+”t) is given by: 

Where, 

xi(t+”t)= xi(t)+v[(t,xi(t)] “t + ni 

ni= Random variables drawn from a normal distribution of probability with mean 0 and 

variance k(t, xi) “t. 

3. Simulation model 

A simulation model may be defined as a simplified imitative representation of the physical, 

chemical, biological and physiological mechanisms underlying insect/ pest growth process. 

If the basic processes of insect life cycle growth and development are properly understood 

and modeled using mathematical tools, the entire response of the insect to its environmental 

conditions can be simulated. Various time interval can be introduced in a simulation model, 

then it is termed as dynamic simulation model. In case of insect life cycle, daily or hourly 

intervals are most practical with assumption that rate computed for an interval does not 

change appreciably during that period. The common structure of the dynamic simulation 

model is of the form: 

j+1 M = p 

j 

Mp + fp (Mj , Xj , Aj )* “t 

Mj = M for j= 0 

o 

Where, 

j M = A functional relationship for estimating biological parameter. 

p 

Mj j 

= A vector consisting of Mp X j = A vector characterizing the current state of environmental 

j j j conditions e.g. X is air temperature, X2 is humidity, X3 is rainfall amount, etc. 

i 

Aj = A functional and numerical parameter of the model 

j = Present time 

j+1 = Next increment in time 

“t = Increment in time 

P = Biological process 

Simulation model can be most useful if model accounts for most relevant phenomena 

and contains no false assumptions. Simulation provides insight into bio-weather relationships, 

explains why some factors are more important for insect/pest growth and development than 

others, suggests factors likely to have statistical significance and provides the basis for 

new experiments on the processes which are apparently important but not yet sufficiently 

understood. 

3.1 Brown plant hopper (BPH) 

This model assumes that all eggs move to the next age class. A proportion of eggs can 

die. The proportional daily mortality of eggs is assumed to be constant (e). 

E 2 , t+1 = E 1 ,t (1-e) 

127

E 3 , t+1 = E 2 ,t (1-e) 

In similar way the eggs are laid by adult between the age of 3 to 4 and 7to8 days old to 

produce the number of 0 to 1 day old eggs may be expressed as : 

Where, 

8 

E 1 ,t= Ó[A i (1-a)f] 

i=4 

A i = Number of adults of age ‘i’ = 4 to 8 days 

a = Daily mortality of adults 

f = Fecundity or number of eggs produced per adult per day. 

Conclusion 

Statistical models are practical, simple as they require minimum input data for predicting 

pest population. These models are more accurate for a particular pest species, host, region 

and time. But they are limited to the environment for which they are developed. These models 

do not explain the cause and effect of relationship between pest and environment. 

Mathematical/ analytical models can serve a useful purpose in indicating key areas or 

relevant questions for the field and laboratory ecologist or simply in sharpening discussion 

of continuous issues. 

The simulation model provides the understanding of the pest environment interactions 

as they are based on the mechanisms involved in the interactions. But the simulation models 

are more complex, requires enormous input data and sophisticated computers. 


Berryman, A. A. 1981. Population Systems : a General Introduction. Plenum ,Press, New 

York. 

Gompertz, B. 1825. On the nature of the function expressive of the law of human mortality. 

Phil. Trans. R. Soc. Lond. 36 : 513-585. 

Mitscherlich, E.A. 1909. Das Gesetz des minimum und das Gesetz des abnehmenden 

bodenortrags Landwirtsch Jahrb. 38 : 537-552. 

Norton, G.A. and Mumford, J.D. 1993. Decision Tools for Pest Management. CAB International 

Wallingford Oxon 0x10 8DE UK. 

Richards, F.J. 1969. The quantitative analysis of growth. In : Steward F.C. (ed.) Plant 

Physiology Vol. V. Academic Press, London, New York. 3-76. 

Schowalter T. D. 2006. Insect Ecology : an Ecosystem Approach. Academic Press in an 

imprint of Elsevier. 

Vanderplank, J.E. 1963. Plant Disease: Epidemics and Control. Academic Press, New York. 

Verhulst, P.F. 1838. Notice sur la loi que la population suit dans son accroissement. Corr. 

Math. Phys. 10 : 113-121. 

128

DIAGNOSTIC SYMPTOMS AND LOSSES CAUSED BY 

MAJOR ENEMIES TO HONEY BEES 

S. K. Sharma 



Like other living beings, the honey bee is also subjected to attack at all stages of its 

development by various enemies acting either directly as predators, or indirectly, by disturbing 

the life of the colony in various ways. The most important of these enemies are those that 

destroy the combs, the stores, the hive itself and some predators that take foraging worker 

bees as they leave the hive, or those that behave as true parasites by raising their offspring 

in the bodies of bees. 

In this article diagnostic symptoms and losses caused by major enemies to honey bees 

are discussed. The enemies which are associated with honey bees are mites, ants, wasps, 

wax moth, termite, beetles and dragonfly. 

1. MITES 

In tropical Asia, the success or failure of beekeeping operations with Apis mellifera 

largely depends on mite control. All known major species of parasitic mites of honey bee 

currently exist in Asia, most being native to the continent. Some species of mites are able 

to survive, or even thrive, on more than a single species of host bee. Several species of 

mites have been reported as causing devastation to both A. mellifera and A. cerana 

beekeeping throughout Asia, though not all mite species found within the hives or in 

association with the bees are true parasites. Table 1 contains a list of parasitic mites 

reportedly found in association with honey bees in Asia. 

1.1 Varroa Mite (Varroasis) 

The original host of this mite is Apis cerana throughout Asia. Since the initiation of 

beekeeping development projects with A. mellifera on the continent, it has been reported as 

causing damage in both temperate and tropical Asia. The overall effect of varroa infestation 

is to weaken the honey bee colonies and thus decrease honey production. Occasionally in 

A. melllfera, and more frequently in A. cerana, heavy infestation may cause absconding. 

Today this parasite is found throughout the world, except for Australia and New Zealand 

South Island. 

Cause 

Varroa destructor Anderson and Trueman is quite large, as compared with other mite 

species, and can be seen with the unaided eye. The mite is reddish brown in colour and 

shiny and the body is dorsoventrally flattened covered with short hairs (setae). Adult females 

Table 1. Bee mites and their hosts 

Mite Mode of living Host Habitat 

Varroa destructor Parasitic A.cerana & A. mellifera Brood cell and adult bee 

Euvarroa sinhai Parasitic A. florea Brood cell and adult bee 

Tropilelaps clereae Parasitic A. dorsata & A. mellifera Brood cell and adult bee 

Acarapis woodi Parasitic A.mellifera & A.cerana Trachea of the adult bee 

Source : FAO technical bulletin 

129

of V. destructor are found inside brood cells or walking rapidly on comb surfaces. Individual 

mites are often seen clinging tightly to the body of adult bees, mostly on the abdomen, 

where the segments overlap, between the thorax and the abdomen and at the ventral entry. 

Adult males, and the immature stages of both sexes (egg, protonymph and deutonymph), 

are not commonly seen outside the brood cells. 

Losses : Varroa mite causes injuries to honey bees by direct feeding. The adult female 

mite pierces the bees’ soft intersegmental membrane with their pointed chelicera and sucks 

the bees‘ haemolymph (‘blood’). The damage to adult bee is only done when the infestation 

is severe. Varroasis is a brood disease. If more than one parasitic female mite infests the 

brood cell the brood deformations occur including shortened abdomen or deformed wings. If 

only one mite infests a cell symptoms may not be visible, although the bees’ life-span is 

considerably shortened. Colonies destroyed by the varroa mite are often left with only a 

handful of bees and the queen, the other bees having died during foraging or having drifted to 

neighbouring colonies, where the mite population can increase before killing these colonies 

also. In this way mites may cause colonies to die, as in some kind of domino effect, over 

wide areas. The presence of adult bees with deformed wings, crawling on comb surfaces or 

near the hive entrance, usually indicates a late stage of heavy mite infestation. Several 

methods may be used to detect mites. The most reliable, perhaps the most time-consuming, 

is direct sampling by the random opening of brood cells, particularly drone cells. The older 

the larvae/pupae the easier this procedure becomes. 

1.2 Tropilaelaps Mite 

Modern beekeeping with Apis mellifera in tropical and sub-tropical Asia frequently 

encounters problems caused by infestation with Tropilaelaps spp. The mite is a native parasite 

of the giant honey bee A. dorsata, widely distributed throughout tropical Asia. 

Cause 

Tropilaelaps mites are much smaller than varroa mites, although the trained unaided eye 

can still see them. When the mites are present in a honey bee colony in large numbers, 

they can be observed walking rapidly on the surface of the comb. They are rarely found on 

adult bees. In all its immature stages, the mite lives within the brood cells of the bees, 

feeding on the brood’s haemolymph. Fertilized adult females enter the cells before they are 

capped to lay their eggs. The stages of development of the mite are as follows: egg, sixlegged 

larva, protonymph, deutonymph, adult. 

Symptoms 

The damage caused to colonies by Tropilaelaps infestation is similar to that brought 

about by Varroa and the injuries inflicted on individual bees and bee brood are essentially 

the same. The abdomen of bees surviving mite attacks is reduced in size, and they have a 

shorter life-span than healthy bees. In heavily infested colonies, bees with deformed wings 

can be observed crawling in the vicinity of the hive entrance and on the comb surfaces. 

1.3 Tracheal Mite (Acarapidosis) 

This mite, Acarapis woodi Rennie, infests the tracheal system of adult bees, queens, 

workers and drones, which are all equally susceptible to its attacks. 

Cause 

A. woodi is a very small mite (0.1 m) species that lives and breeds within the thoracic 

tracheae of adult bees. The mite penetrates through the stigma (spiracles) into the first 

130

trachea pair of the thorax of 10-day old honey bees. There it lays eggs at intervals of a few 

days. After the deutonymph stage, male offspring emerge after around 12 days and females 

after 13 to 16 days. 

Symptoms 

The most reliable diagnostic method is laboratory dissection. Samples of 20 or more 

bees found crawling near the hive and unable to fly are killed, their heads and legs removed 

and their thoraxes dissected for microscopic examination. If present, the mites are usually 

found at the end of the first pair of trachea in the thorax 

2. Ants 

Ants are among the most common predators of honey bees in tropical and subtropical 

Asia. They are highly social insects and will attack the hives en masse, taking virtually 

everything in them: dead or alive adult bees, the brood and honey. Ants may harm bees in 

various ways. Some species, in particular those in the sub-families of Dorylinae and 

Ecitoninae, which include the army ants, are capable of destroying a whole apiary within a 

few hours. They behave as fearsome predators of adults, larvae and eggs. Other ants disturb 

the colony in their eagerness to steal honey (Formica rufa, Formica sanguine, Formica 

fusca, Lasius niger) or pollen (Crematogaster jherinil) (Santis and De Regalia, 1978). Other 

species such as Camponotus herculeanu ssp. pennsylvanicus attack the wood of the hives 

or their supports (Burril, 1926). 

Generally, most of the ant species are not very damaging to bees even though they 

occasionally roam around inside the hives, looking for food. Also, they may establish their 

nests between the cover board and the roof, taking advantage of the warm, humid environment, 

which provides them with optimal nesting conditions. Queen mating nuclei containing very 

small populations of bees, are most vulnerable to attack by ants. 

In addition to this destruction, they can also be a nuisance to beekeepers and may 

sometimes cause pain from their bites. Apiaries of Apis mellifera under ant attack become 

aggressive and difficult to manage; weak colonies will sometimes abscond, which is also 

the defence of A. cerana against frequent ant invasions. Many ant genera and species are 

reported to cause problems to both traditional beekeeping with A. cerana and to modern 

beekeeping with A. mellifera. 

Losses : In India, not much work has been done on the ants in relation to honey bees. 

Singh and Naim (1994) reported Teteraponera rufonigra (Jerdon) as pest of honey bees Apis 

cerana during monsoon season. They found that attack resulted in complete destruction of 

8.0 to 9.0 per cent of colonies and partially destruction of 8.0 to18.0 per cent of the colonies 

3. Termites 

Termites are wood –infesting creatures and since most bee hives are made of wood, 

termites have to be listed as a hive pest. Termites are only after the wood-not bees or honey. 

Hives placed on the ground or bee equipment left lying around on the ground or stacked 

directly on the ground may be subjected to termite infestation. If termites destroy the bottom 

board the bees may not have a bottom entrance and the colony could be more difficult to 

move. 

When bottom board is damaged by ants, there are chances of attack of wax moth in the 

hive. Colonies would be unable to maintain the hive temperature; ultimately it will effect the 

growth and development of colony. 

131

4. Wasps and Hornets 

The hornets have curious attitude of swooping down on anything dark on the flower (De 

Jong, 1979). Vespa crab can undertake co-ordinated attacks with such a great number of 

individuals that whole apiaries may be depopulated. The bees cannot, on their own, offer 

great resistance to the hornets. Wasps of the Vespula and Dolichovespula type are not 

important predators of bees. 

Colonies of both A. cerana and A. mellifera are frequently attacked. Hornet invasion of 

A. cerana colonies generally causes the bees to abscond, and similar behaviour is reported 

of weak colonies of A. mellifera. In addition to hornets of the genus Vespa, other wasp 

species have occasionally been reported to cause damage to apiaries. Among these are 

several species of the genus Vespula, which are distributed throughout temperate Asia. 

Table 2 lists wasps and hornets that have been reported as major predators of the two honey 

bee species in Asia. Predation by Vespa spp. on commercial apiaries is generally a seasonal 

problem. 

Table 2. Wasps and hornets that attack bees in Asia 

Scientific Name Recorded Distribution 

Vespa orientalis India, Pakistan 

Vespa mandrina India, Burma, Thailand, Lao, Vietnam, Democratic Kampuchia, 

China, Republic of Korea, Japan 

Vespa tropica Tropical Asia 

Vespa velutina Tropical Asia 

Vespa cincta Tropical Asia 

Vespa affinis Tropical and Sub tropical Asia 

Vespa crabro Japan and perhaps whole temperate Asia 

Vespa mongolica Japan and perhaps whole temperate Asia 

Vespula lewisii Japan 

Vespula vulgaris Republic of Korea 

Source : FAO technical bulleitin 

Extent of losses : On an average 20-25 per cent of bee colonies are lost due to persistent 

wasp attack. The wasp, attacks usually coincide with dearth periods when bee forage 

sources, as nectar and pollen are scarce. Of all the Vespa spp. preying Apis mellifera and 

A. cerana, V. cincta, V. velutina and V. basalis are the most serious and caused heavy 

losses by feeding on adult bees , their brood and honey reserves. Apis mellifera is relatively 

more susceptible to wasps attack than A. cerana and predation often coincides with flowerless 

dry season. When three or more hornets have been attracted to the hive en masses; a 

colony of 30000 bees can be killed in three hours by 20-30 hornets. Predatory wasps pose 

a serious threat to beekeeping as 20-30 per cent of bee colonies desert their hives annually 

due to predatory wasps attacks. 

5. The greater wax moth (Galleria mellonella L.) 

The greater wax moth is the most important pest of honey bees world wide because of 

its serious losses it can inflict (Smith, 1960; Singh, 1962). They destroy a large number of 

combs every year, attack the wax foundation and can reduce stored combs and weak colonies 

to a pile of debris. Wax moths only cause considerable damage in apiaries if the colonies 

they attack are incapable of repelling them. The susceptibility of the colony to attack may 

132

e due to several causes: malnutrition, disease, loss of the queen or large scale mortality of 

the worker bees due to poisoning by pesticides. Wax moths may also be implicated in the 

spread contagious diseases, especially foulbrood, by consuming contaminated combs. 

The newly-hatched Galleria larvae feed on honey and pollen, and then burrow into pollen 

storage cells or the outer edge of cell walls, later extending their tunnels to the midrib of the 

comb as they grow. At this stage the developing larvae are quite safe from the worker bees. 

As they advance into the combs, they leave behind them a mass of webs and debris; the 

complete destruction of unattended combs usually ensues within 10-15 days. In addition to 

stored pollen and comb wax, larvae of the greater wax moth will also attack bee brood when 

short of food. 

Symptom : When weak colonies are infested, the symptom of ‘galleriasis’ is frequently 

observed: the emerging adult worker and drone bees are unable to leave their cells because 

their bodies have been tied up by silken threads spun by the Galleria larvae. 

Extent of losses : Adult of wax moths causes no damage because their mouth parts are 

atrophied. They do not feed during their adult life. Only larvae feed and destroy combs. 

However, adult wax moths and larvae can transfer pathogen of serious bee diseases. 

6. The lesser wax moth (Achroia grisella L.) 

Symptom : Infestation by the lesser wax moth usually occurs in weak honey bee colonies. 

The larvae prefer to feed on dark comb, with pollen or brood cells. They are often found on 

the bottom board among the wax debris. As larvae prefer to form small canals between the 

bottoms of the brood cells the brood is lifted. The bees continue constructing cells heading 

upward leading to the typical scratched comb surface. 

7. Other Lepidoptera 

Other moth species are frequently recorded in association with bees and bee products. 

The Indian meal moth Plodia interpunctella is reported to feed on bee-collected pollen. Moths 

found dead on the bottom boards of beehives include death’shead or hawk moths (Acherontia 

atropos), which invade the hives to feed on honey. Beekeepers generally consider them to 

be minor pests. 

8. Beetles 

There are several different beetles living in honey bee colonies. Most are harmless and 

feed on pollen or honey. 

Small hive beetle (SHB) (Aethina tumida Murrey) : 

Symptoms 

The beetles and their larvae can infest bee brood and honeycombs in and outside the 

apiary. There they form eating canals and destroy the cell caps, and the honey starts to 

ferment. The beetles larvae and faeces also change the colour and taste of the honey and 

the combs appear ucilaginous. 

A minor infestation is difficult to recognize because the beetles immediately hide in the 

dark. The most secure diagnosis is achieved after chemical treatment when the dead beetles 

can be gathered from the bottom inlay. 

Extent of losses : Beetle larvae do the most damage in the colony, burrowing through 

brood combs and consuming the brood and stores. The level of harm to the colony depends 

133

on the number of beetle larvae present. Once present in large numbers, the survival of the 

colony is at great risk. Queens stop egg laying and colonies can quickly collapse. In heavy 

infestations, tens of thousands of SHB larvae may be present within the colony. In such 

cases there can often be up to 30 larvae per cell. Such large numbers can generate enough 

heat inside the hive to cause comb to collapse and subsequently for the colony to 

abscond.SHB larvae affect combs of stored honey and pollen and will also infest brood 

combs. During the feeding action by larvae an associated repellent sticky substance is laid 

down on the combs and this can result in bees abandoning the hive. By defecation of adult 

beetles and larvae in honey combs causes the to ferment and drip out of cells 

9. Dragonfly 

Some of the larger species of dragonflies, also commonly referred to as mosquito hawks 

or darning needles, feed on honey bees. Nearly all dragonflies are predaceous and capture 

their prey while flying. They arrange their six legs into a basket shape to capture flying 

insects. They may eat the prey while flying or upon landing. Since the immature stage, a 

naiad, lives in the water, adult dragonflies rarely wander far from rivers or lakes. 

Needham and Heywood (1929) labeled dragonflies as harmless, if not useful insects, in 

all but their relationship with honey bees. They stated that dragonflies may make queen 

rearing impractical and unprofitable. The ground in apiaries where dragonflies are feeding 

may be covered with the discarded legs and wings of both honey bee sexes. 

In Europe, as in North America, dragonflies are known as bee pests. Betts (1939) did 

not find dragonflies as serious enemies of honey bees in England. He believed that dragonflies 

should be protected except where queens are being reared. 


Abrol, D.P. 1997. Honey Bee Diseases and their Management. Kalyani Publishers, Ludhiana: 

607 p 

Mishra, R.C. 1997. Perspectives in Indian Apiculture. Agro-botanica, Bikaner : 412p. 

Morse, R.A. 1978. Honey Bee Pests, Predators and Diseases. Cornell University Press, 

Ithaca: 430 p 

Singh, S.1962. Beekeeping in India. Indian Council of Agricultural Research, New Delhi. 

214p. 

134


LOSSES DUE TO ARTHROPOD PESTS IN CROPS 

M. K. Dhillon 

Division of Entomology, Indian Agricultural Research Institute (IARI), 

New Delhi 110 012, India 

Crop plants are damaged by more than 10,000 species of the arthropods, however, less 

than 10% of the total identified pest species are generally considered as major pests. The 

outbreak of an insect pest quiet often becomes a major concern of the farmer. Every crop is 

infected by enormous number of insect pests from sowing to harvest, a few of them are of 

major economic importance and are taken into account for the assessment of crop losses 

caused by them, while rest of the minor insect pests too cumulatively contributes to 

considerable share of yield loss in a given crop in space and time. Some times it is also 

difficult to identify some of the insect pests whose damage symptoms are very conspicuous 

and goes unnoticeable, but causes considerable yield losses. The damage or loss caused 

by the insects cannot be quantified without considering the pest in relation to its environment 

or to its interaction with other organisms. Besides an accurate identification of the causative 

pest, other prerequisites for integrated crop protection measures include detailed information 

on the extent of damage and the resulting yield losses. This information is available for a 

number of important crops, but is inadequate or completely lacking for many basic food 

crops. The amount of detail needed for a crop damage assessment must be decided within 

the restrictions of budget and logistics. The minimum amount of data needed to understand 

the situation should be the baseline. However, in some cases more data need to be collected. 

Information about spatial and temporal patterns of crop damage, the type of crop(s) involved, 

area of standing crop damaged or the number of plants damaged relative to the size of the 

field, and/or an estimate of the monetary losses as a consequence of crop damage may well 

provide valuable information. 

Diagnostic symptoms of damage by various insects in different crops 

The damage pattern and symptoms by insect pests depends on their mode of feeding, 

and varies across group of insects. Plant tissue feeding or sap sucking are the major mode 

of insect feeding. The mode of feeding and the diagnostic symptoms of damage by some 

major insect pests are elaborated hereunder: 

Sap sucking insects : 

The sap sucking pest damaged plants, in general, produce pale specks on the points it 

makes puncture and secrets the sweet substance or honeydew which leads to sooty mould 

development on leaf surface, obstruct sunlight and retard photosynthesis, resulting in poor 

and stunted plant growth, or the damaged plant dries up. Hereunder are some of the peculiar 

symptoms of damage by sucking pests in different crops : 

Damage by thrips and mites result in leaf discoloration, while damage by aphids and 

psyllids result in leaf deformity. 

The brown plant hopper affected rice crop dries up and gives “hopper burn” in circular 

patch, while white backed plant hopper damage result in “hopper burn” in irregular patches. 

The head bug damage in sorghum produces shrinked, black colored and ill filled (chaffy) 

chaffy panicles, as a result of sucking of juice in the milky stage of the sorghum grains. 

135

The shoot bug damage in sorghum result in unhealthy, stunted and yellow plants, and 

the leaves wither from top downwards, panicle formation is inhibited, the plants die if the 

attack is severe, and honeydew secreted by the bug causes growth of sooty mould on 

leaves. 

The white fly, Bemisia tabaci damaged tomato plants produce curly leaves as a result of 

transmission of leaf curl virus showing vein clearing symptoms. Similarly, the white fly 

also transmits yellow vein mosaic virus (YMV) in soybean, mungbean and blackgram, 

where in case of severe infestation of YMV, very few pods are formed, which are reduced 

in size with smaller and shriveled grains. 

Leaf hopper damage in okra produces leaf cupping symptoms. 

Foliage feeders and stem/fruit boring insects 

The foliage feeding insects generally nibble the leaves either on margin or on surface, or 

leaf skeletonized, or defoliation, which are the major symptoms of damage by beetles, 

caterpillars, crickets, and grasshoppers. The damage by borers on the foliage/ in the plant 

stem result in leaf scarification, stunted growth, bunchy top, shot holes, deadheart, silver 

shoot, etc. The fruit damage is detected by observing holes in the fruits, however, in some 

cases the damage in the fruits is not easy detected since the holes they make on surface 

soon heal up removing all traces of existence inside, and can only be detected after fruits 

are cut open. Hereunder are some of the peculiar symptoms of damage by borer and foliage 

feeding insects in different crops: 

Yellow stem borer, Scirpophaga incertulas damage in rice is detected by observing 

deadhearts in the seedling stage and ‘white ears’ at the reproductive stage of the crop. 

Leaf folder or leaf roller, Cnaphalocrocis medinalis damage in rice is detected by observing 

the scrapping of the green tissues of the leaves which makes them white and dry, and 

during severe infestation the whole field exhibits scorched appearance. 

The gall midge, Orseolia oryzae maggots feed at the base of the growing shoot causing 

formation of a tube like gall that is similar to ‘onion leaf’ or ‘silver-shoot’ in rice. 

The nymphs and adults of grasshopper, Hieroglyphus banian cause enormous losses to 

the crop by chewing and cutting various plant portion viz., leaves, flowers and grains. 

The maggots of shoot fly cut growing tip of the central of the cereal crops resulting in dry 

up of the central leaf called ‘deadheart’. The deadhearts caused by shoot fly can be 

easily pulled out and gives foul smell. 

The young larva of spotted stem borer, Chilo partellus crawls and feeds on tender folded 

leaves causing typical ‘shot hole’ symptom, which then cuts the central growing top 

resulting in central shoot withering and leading to ‘deadheart’ formation. The stem borer 

deadheart can not be pulled out easily. With the elongation of the plant stem bore holes 

are also visible on the stem near the nodes. 

The Helicoverpa armigera damage can initially be seen as leaf scarification by larvae, 

however, more clear damage symptoms of this pest are visible as circular feeding holes 

on flowers, flower buds, and fruits/pods/bolls in tomato, chickpea, pigeonpea, cotton, 

etc, where the larger larvae bore into reproductive parts and consume the developing 

seeds. 

136

Pest populations and crop losses 

The loss in a crop is directly related to the population of the insect pests. Therefore, 

extensive studies are needed to understand the distribution pattern of insect population, to 

predict the likely damage to be caused, to initiate control measures, and to relate changes 

in the population to certain climatic or edaphic factors, and are integral part of the assessment 

of crop losses due to insect pests. The pest population density can be measured with 

following three estimates: 

Absolute estimate : The total number of insects per unit area is the absolute estimation, 

for e.g., per ha, 2 m row length, 1 m 2 quadrant, etc. The numbers of insects per unit of the 

habitat indicate the density of population, e.g., per plant, or shoot, or leaf, or flower, or fruit, 

etc. The estimates of absolute population and population density are used for preparing life 

tables, study the population dynamics, and to calculate population buildup under field 

conditions. The absolute insect pest populations are generally estimated through quadrant 

method (immobile and relatively large insects, and for tissue borers by collecting and splitting 

open the damaged plant parts), line-transect method (quantitative comparisons between 

different species and between different occupiers of habitats like locusts and grasshoppers), 

or capture, marking, release and recapture technique (flying insects). 

Relative estimate : In relative estimate of the insect population, the samples usually 

represent an unknown constant proportion of the population. Such estimates are useful in 

making comparisons in space and time. These are useful for studying the activity patterns 

of a species or for determining the constitution of a polymorphic population. The methods 

employed for relative estimates include the catch per unit time or effort (use of various types 

of sweep nets depending on insect species and vegetation) and the use of various types of 

traps (interception traps like flight, aquatic, pitfall, light, etc., to catch the insects randomly; 

and attraction traps like use of some natural stimulus, bait traps, chemical attractants, 

pheromones, etc. for attraction of insects). 

Population indices : Population indices don’t count insects, but are measures of insect 

products or effects. Under field conditions, it is not possible to estimate the absolute 

population in most of the cases. Therefore, it becomes necessary to establish a relationship 

between absolute estimates and population indices or the relative estimates so that the 

latter two types of estimates could be converted in to absolute terms by using certain 

correction factors. 

In some cases, a species that is difficult to sample creates products directly that are 

easily sampled by absolute methods. The insect product most often sampled is frass or 

excrement of lepidopterous defoliators. The rate at which frass is produced can be estimated 

from the amount falling into a box or funnel placed under the trees. The size and shape of 

the frass pellets is rather constant for a given species and instar, and allows identifying the 

species and age composition of defoliators. The amount of damage caused by insects to 

crop plants is a function of the pest density, the characteristic feeding or oviposition behavior 

of the species and the biological characteristics of the plants. Different methods have to be 

adopted for measuring damage by direct (pests attacking the produce directly such as 

bollworms on cotton and fruit borers in fruit and vegetable crops) or indirect pests (measured 

by estimating the extent of defoliation like lepidopteran caterpillars, leaf beetles, 

grasshoppers, etc.). The damage by direct pests is sampled on the basis of absolute or 

relative numbers of damaged unit, e.g., number of damaged bolls/plant, damaged pods/ 

meter row length, damaged apples/tree, etc. 

137

Yield loss assessment 

The loss suffered by a crop is a function of the pest population, behavior of the pest and 

the crop plants. Damage to the plant occurs because of the effect of injury by the insect, 

and a simple damage to the plants may or may not lead to crop loss. The reduction in 

quantity/quality of the produce is the crop loss. The loss in quality may affect the appearance 

of the crop produce, its nutritive value or it may result in the produce being rendered unfit for 

use. Insect pests damage crop plants either by feeding or during the process of oviposition. 

Some of the insect pest species are host specific which feed on the plants of a single 

species termed as monophagous. Others attack plant species belonging to the same family 

and are known as oligophagous. The insect species capable of infecting plant species 

belonging to several diverse families are called polyphagous. Some of the pests are strictly 

specific as regards their site of feeding and oviposition, for e.g., leaf hoppers, leaf miners, 

fruit borers or root borers, etc. They cause damage to only one part of plant. There are 

others, like the locust and some species of beetles that can attack several parts of the 

same plant simultaneously. The losses due to insect pests can be categorized in many 

ways, depending upon the significance of pests and their management. 

Direct losses : The direct losses relate to decrease in productivity (quantitative) or 

intrinsic value/acceptability of the produce (qualitative). Direct quantitative losses include 

killing of flowers, buds, twigs of whole plant because of infestation by a pest having either 

chewing or piercing-sucking mouth parts, e.g. locust and grasshoppers, bollworms, fruit 

borers, etc. The direct qualitative losses include light infection of fruits by the scales, 

puncturing of normal fruits immediately before harvest owing to feeding or ovipositional activity. 

Damage by the pests to the fruit trees from the blooming to harvesting period result in 

quantitative loss in the earlier phase and qualitative ones in the later phase. 

Indirect losses : The indirect losses are primarily of economic interest such as decreased 

purchasing power of the agriculturists and those depending upon agriculture owing to reduced 

production. This would lead to decrease in related activities, reduced productivity of agrobased 

industries, expenses incurred for importation of agricultural produce, and also forced 

acceptance of less desirable substitute products. 

Actual losses : The actual crop is determined in terms of total value of the quantitative 

(direct) and qualitative (indirect) losses, and the cost of control measures alongwith the 

amount spent on research for developing knowledge and tools for the control of insect pests 

by the agriculturists. 

Methods of estimation of losses 

The amount of damage caused by insect pests of crop plants is a function of the feeding, 

oviposition, and biological characteristics of the pest population, biological characteristics 

of the host plants, and their interactions with both biotic and abiotic environmental factors. 

Sometimes it is difficult to establish correlations between the levels of pest population and 

plant damage, however, the estimation of damage is critical for pest management. The 

evaluation of damage is helpful in recognizing relative economic importance of different pests, 

defining the economic status of a pest species, estimating the effectiveness of control 

measures, evaluating crop varieties for their resistance to pests, and helpful in deciding the 

allocations for research and extension in plant protection. Hereunder are some techniques 

being used for the assessment of crop losses caused by insect pests. 

Mechanical protection : The crop is grown under enclosures of wire gauge or cotton 

cloth. The enclosures keep the pest away from the crop. The yield under such enclosures is 

138

compared with that obtained from the infected crop under similar conditions. The technique 

has been used with various modifications for estimating the losses caused by leafhopper 

and whitefly in cotton. In the case of non-flying insects, sometimes, the barriers are substituted 

for the cages. Change in microenvironment and its effect on plant growth and development is 

the major limitation of use of this technique, which also can not be adopted on a large scale 

as is time consuming, uneconomic and impracticable on field scale. 

Chemical protection : The crop is protected from pest damage through the application 

of pesticides. The yield of treated crop is compared with the normal infested and unprotected 

crop. This technique has been widely used, and it can be adopted on a large scale under 

farmer’s field conditions. As a thumb rule while measuring crop losses through chemical 

protection, it needs to be ensured that the treated and untreated fields/plots have similar 

soil type, manuring, variety and cultural practices, however, physiological effect of chemical 

application can also increase or decrease in crop yield and can not be completely ruled out. 

Pest incidence in different fields : The yield is determined per unit area in different 

fields carrying different degrees of pest infestation. The correlation between the crop yield 

and degree of infestation is worked out to estimate the loss in yield. Although, this technique 

can be used for estimating crop loss due to different pests and diseases over a large area, 

the crop yield also get influenced due to heterogeneity in soil, fertility gradient and variability 

in local climate, which needs to be addressed while estimating the yield losses due to 

insect pests. 

Pest incidence on individual plants : In this case, individual plants from the same 

field are examined for the pest incidence and their yield is determined individually. The loss 

in yield is estimated by comparing the average yield of healthy plants with that of plants 

showing different degrees of infestation. The same data also can be used for working out a 

correlation equation between yield and infestation on the basis of individual plants. The 

advantage of this technique over the preceding one is that soil heterogeneity factor is 

considerably reduced in the same field. However, different plants showing varying degrees of 

infestation in itself is a proof that plants differ from one another in some unknown factors 

due to which they carry different degrees of infestation. This factor may be genetic or 

physiological or it may be mere soil heterogeneity in the same field. Moreover, this method 

is very time consuming and involves lot of labor. 

Damage by individual insect : Preliminary information on the damage caused by 

individual insect is obtained from studies on biology of pest species. The details regarding 

the amount of damage caused by different stages or ages of the pest, and the exact nature 

and amount of loss caused are then worked out. This technique is quite easy in the case of 

leaf feeding insects, however, it is very difficult to use over large areas since it is very time 

consuming. 

Simulated damage : This technique involves simulation of pest injury by removing or 

injuring leaves or other parts of the plant. The simulated damage may, however, not always 

be equivalent to the damage caused by an insect. Insects may persist over a period of time 

or inject long acting toxins rather than producing their injury instantly. Feeding on leaf margins 

may not be equivalent to tissue removal from the centre of the leaves. 

Thus, any of the above methods can be suitably modified and used for estimating loss in 

yield of a given crop. The degree of pest infestation and the damage caused by it may differ 

from field to field in the same season, and from season to season in the same field. It is, 

therefore, imperative to work out the average values. In case the crop losses have to be 

139

worked out on the regional/state basis, the numbers of places from where estimations have 

to be made are more important than the degree of precision of the technique employed. 

Estimation of economic value of the crop losses due to insect pests 

To estimate the economic value of losses due to damage by insect pests, the actual 

losses need to be measured. The crop loss is the difference between actual yield (Ya) (with 

damage by target insect pest) and the potential yield (Yp) (without the insect pest’s damage), 

which then after multiplying by the area of the region and the price of crop harvest, an 

economic evaluation of crop loss due to target insect pest(s) can be made. Furthermore, it 

is convenient to express this difference as a proportion of the potential yield (Yp), to obtain 

a proportional crop loss (r). 

Thus, r = (Yp – Ya)/Yp 

The ratio r can be obtained from different sources such as farmer’s estimates, expert’s 

estimates, or crop loss estimates from the field. If this ratio r is known, loss can then be 

derived from actual yield with following formula: 

Yp – Ya = Ya × (r/1–r) 

Similarly, crop loss for an area or for a country can be defined as the difference between 

potential production (Pp) and actual production (Pa), where in by knowing the “r”, we can 

estimate the absolute crop losses caused by target insect pest(s) using the below given 

formula : 

Pp – Pa = Pa × (r/1–r) 

The crop losses can also be derived through ratio or absolute value obtained indirectly from 

occurrence, incidence, or damage indicators. Occurrence is usually expressed as a binary variable 

(present/absent), incidence is the extent of occurrence or the number of insects per plant or per 

unit area, and the damage is assessed by counting the number of infested plants. In general, the 

number of insects (n) can be estimated through a damage score or rating (x), which thus can be 

expressed as n = f(x). This function can thus be estimated through regression, and several other 

functional forms available. Alternatively, yield Y can be directly related to a set of insect damage 

indicators (d), with a set of other relevant variables (z) such as management practices, variety, 

etc., and thus can be expressed as : Y = f (d, z). Once this relationship and its precision are 

established, it provides more economical way of estimating yield loss than direct estimation in 

trials. It is possible to develop cost functions to calculate the cost of obtaining a crop loss 

estimate within a given error margin. Finally, to obtain an economic evaluation, losses need to be 

multiplied by prices. 


De Groote, H. 1996. Optimal survey design for rural data collection in developing countries. 

Quarterly Journal of International Agriculture 35 : 163–175. 

Kranz, J. 2005. Interactions in pest complexes and their effects on yield. Journal of Plant 

Diseases and Protection 112 (4) : 366–385. 

Le Clerg, E.L. 1971. Field experiments for assessment of crop losses. In : Crop Loss 

Assessment Methods (Chiarappa, L., ed.). Commonwealth Agricultural Bureaux, Farnham 

Royal, UK, pp. 1-11. 

Pradhan, S. 1964. Assessment of losses caused by insect pests of crops and estimation of 

insect population. In: Entomology in India. Entomological Society of India, New Delhi, 

India, pp. 17-58. 

Teng, P.S. (ed.). 1991. Crop Loss Assessment and Pest Management. APS Press, The 

American Phytopathological Society, St Paul, Minnesota. 

140


DUE TO INSECT-PESTS IN FORAGE CROPS 

S. P. Singh 


CCS Haryana Agricultural University, 

Hisar-125004, India 

The forage crops include all plant species consumed by animals, thereby cover large 

number of cereals and legume plants. In India, the cultivated major fodder crops include 

plant species such as sorghum, Egyptian clover (berseem), cowpea and clusterbean (guar). 

Insect pests are one of the major constraints in increasing and stabilizing the production 

and productivity of forage crops. A number of insect pests inflict moderate to sever quantitative 

and qualitative losses to these crops. Pest wise information about diagnosis symptoms of 

pests’ damage and assessment of losses due to major pests infesting forage crops are 

described below. 

I. SORGHUM 

a) Shoot Fly, Atherigona soccata (Rondani) (Muscidae: Diptera) 

The first-instar larva cuts the growing point, which results in wilting and drying of the 

central leaf, known as a dead heart. The dead heart produces a bad smell and it can be 

pulled out easily. Normally, the damage occurs at one week to four weeks after seedling 

emergence. The damaged plants produce side tillers, which may also be attacked further. In 

northern India, there are two distinct peaks of shoot fly activity i.e., during March to mid 

May and mid July to September. 

b) Spotted Stem Borer: Chilo partellus (Swinhoe) (Pyralidae: Lepidoptera) 

It is a major pest of sorghum and attacks all stages of crop growth after 15 days of 

germination. The stem borer also damages maize and bajra crops. The first indication that a 

plant is infested is the appearance of small elongated windows in young whorl leaves where 

the larvae have eaten the upper surface of the leaf but have left the lower surface intact as a 

transparent window. 

The stem borer injury to sorghum includes leaf feeding, tunneling within the stalk, 

disruption of the flow of nutrients to the ear, and subsequent development of “dead hearts”. 

The first symptoms of stem borer damage are the appearance of “shot-hole” injury to whorl 

leaves. “Dead hearts” result from larval feeding injury to the growth point of sorghum plants; 

this damage is most important during the first 2-3 weeks after seedling emergence. 

Assessment of losses in sorghum due to shoot fly and stem borer 

Techniques of estimation losses caused by shoot fly and stem borer infesting sorghum, 

to grow the crop as free from insect infestation as possible and then to compare its yield 

with that of the check in which the insect activity has been normal. The following methods 

have been suggested on the basis of various techniques developed so far for estimating the 

losses caused by insect pests. 

i) Mechanical protection of the crop from pest damage : 

Efforts have been made to grow the crop under iron mesh cage to keep out the pest, and then 

to compare the crop yield with that obtained from infested crop grown under infested conditions. 

141

ii) Chemical protection of crop from the pests under investigation : 

An effort is made to protect the experimental crop by the recommended pest control 

schedule, and the yield is compared with that under normal insect infestation. This technique 

is widely used for estimating the losses caused by insect pests. 

Singh (1986) estimated the avoidable losses in six forage sorghum varieties due to shoot 

fly and stem borer under protected and un-protected field conditions by protecting crop with 

0.05% endosulfan at 12, 22 and 32 days after crop sowing. The following formulae were used 

for calculating per cent avoidable loss and increase in yield. 

Per cent avoidable loss = y – y’/ y x 100 

Per cent yield increase = y - y’ / y’ x 100 

Where, y and y’ are the increase are the mean yields in the sprayed and unsprayed 

plots, respectively. 

iii) Comparison of the yield in field having different degrees of pest infestation : 

Under this method, different degrees of pest infestation is to be maintained by applying 

the insecticide at various intervals and then to work out yield losses. 

The yield loss in sorghum due to C. partellus was estimated by Taneja and Nwanze 

(1989). During 1982 and 1983 yield losses in unprotected plots were 60 and 62 per cent, 

respectively. 

Thobbi and Mohan (1971) reported 70.7 per cent reduction in dead heart formation and 

about 34.0 per cent avoidable losses in fodder production due to protection of the crop from 

the shoot fly damage. Pasalu and Narayana (1975) revealed about 25.6 per cent avoidable 

losses against this pest. Further Thobbi et al. (1975) found that the dead hearts can be 

reduced upto 78.0 per cent and about 50.0 per cent fodder yield can be increased with the 

protection of the crop from the shoot fly attack. Jotwani et a1. (1979) calculated 52.4 per 

cent increase in fodder yield of the shoot fly protected as compared to the unprotected crop. 

Sukbani and Jotwani (1981) obtained 20.2 per cent increase in fodder yield over the control 

when the crop was sprayed with 0.05 per cent diazinon. In forage sorghum, Sandhu and 

Dhaliwal (1982) obtained 68.8 per cent increased fodder yield and 67.5 per cent reduction in 

dead hearts due to shoot fly in the protected crop over the control. Bhanot et al.(1983) 

recorded an overall of 14.8 percent increase in fodder yield when several varieties of forage 

sorghum were protected against this pest and also estimated 45.7 per cent avoidable losses 

in fodder yield when forage sorghum crop was protected against shoot fly. Overall, the 

avoidable loss due to this pest in forage sorghum is about 30 per cent. Economic threshold 

for shoot fly is 20 per cent dead hearts or 5 per cent plants with eggs, 10 days after germination 

(Singh, 2006). 

The information on the losses caused by the stem borer in forage sorghum is rather 

scanty. Jotwani (1971) estimated about 50 per cent losses in fodder yie1d due to stem 

borer. Kundu et al. (1977) reported 38.0 per cent avoidable losses due to stem borer in 

sorghum. In studies on forage sorghum, Gupta et al. (1980) achieved. 95.6 per cent reduction 

in dead hearts by this pest in treated over the control plots. Kundu and Kishore (1980) 

worked out 48.4 per cent avoidable loss due to this pest in fodder yield. Singh et al. (1982) 

calculated 32.2 per cent avoidable loss in fodder yield against this pest and about 80.0 per 

cent reduction in dead heart formation in forage sorghum. Bhanot et al. (1983) estimated 

about 60.0 per cent avoidable losses in fodder yield due to this pest. 

142

II. COWPEA AND CLUSTERBEAN 

a) Aphid, Aphis craccivora Koch 

Colonies of aphids are found on the stems, leaves, and pods of cowpea and guar plants. 

Nymphs and adults suck sap from underside of the leaves, top shoots and stems, as a 

result of which the plants become discoloured and weak. Infestation in the early stage causes 

stunting of the plants as well as reducing the vigour. 

The economic threshold is 10 per cent infested plants. The avoidable losses due to this 

pest in cowpea and clusterbean seed crops are about 20 per cent. 

b) Leafhopper, Empoasca kerri Pruthi 

Both nymphs and adults suck sap from the leaves, which in severe cases of attack turn 

yellow to reddish brown. The attacked leaves later curl up, become distorted and fall down. 

The nymphs and adults prefer shady areas and generally remain on the lower surface of the 

leaves. 

The pest appears on these crops during the rainy season and attacks through out the 

growth stage. Besides cowpea and guar, it also attacks berseem, lucerne, soybean, potato 

and tomato crops. Economic threshold for leafhopper is 2 nymphs per leaf based on 30 

leaves or 20 per cent fully developed leaves start curling. The avoidable losses due to this 

pest in cowpea and clusterbean seed crops are about 30 per cent. 

c) Pod Borer, Helicoverpa armigera (Hubner) 

The young larva feeds on the foliage for some time and later damages the flower buds, 

pods and feed on the developing grains and can reduce the seed yield up to 60 per cent. A 

single larva may destroy 30-40 pods before it reaches maturity. Characteristically, while 

feeding, the head will be thrust inside leaving rest of the body out side. 

The pest appears on these crops during the rainy season and attacks through out the 

growth stages of the crop. Besides cowpea and guar, it also attacks berseem, lucerne and 

tomato crops. Economic threshold for pod borer is 0.5 larva per plant (10 larvae per 20 

plants) or 5 per cent pods infested. The avoidable losses due to this pest in cowpea and 

clusterbean seed crops are about 25 per cent. 


Sharma, H.C. and Nwanze, K.F. 1996. Insect Pests of Sorghum and their Management. 

ICRISAT, Patancheru, India. p.29. 

Singh, S.P. l997. Effect of genotypic resistance on avoidable losses and economic thresholds 

for the spotted stem borer, pages : 46-51. In : Plant Resistance to Insects in Sorghum. 

(Eds: Sharma, H.C., Singh,F., Nwanze, K.F.). ICRISAT, Patancheru, A.P.,India. 

Singh, S.P. 2000. Insect pest management in forage crops. Proc. Advanced Training Course 

on Recent Advances in Integrated Pest Management. 1-21, December, 2000, Department 

of Entomology, CCS Haryana Agricultural University, Hisar, India.pp. 283-292. 

Singh, S.P. 2010. Recent Advances in Biointensive IPM in Forage Crops. Proc. Advanced 

Training Course on Recent Advances in Biointensive Integrated Pest Management, 

Department of Entomology, CCS Haryana Agricultural University, Hisar, India. pp.123- 

130. 

143

Singh, S.P. and Chhillar, B.S. 2010. Insect-pest management in legume forage crops. pages: 

241-262. In : Forage Legume (Eds. Jai Vir Singh, B. S. Chhillar, B.D. Yadav and U.N. 

Joshi), Scientific Publishers (India), Jodhpur, Rajasthan 

Singh, S.P., Chhillar, B.S. and Het Ram 2004. Relative efficacy of bio-insecticides against 

pod borer, Helicoverpa armigera (Hubner) in berseem seed crop and estimation of yield 

losses. Forage Research, 30 (1) : 31-33. 

Singh, S.P., Luthra, Y.P. and Lodhi, G.P. l995. Assessment of quantitative and qualitative 

losses caused by stem borer, Chilo partellus (Swinhoe) in forage sorghum. Forage Res. 

21 (3) : 109-113. 

Singh, S.P. and Verma, A.N. l989. Extent of losses caused by stem borer, Chilo 

partellus(Swinhoe) in forage sorghum. Pesticides 23 (2) : 19-22. 

Singh, S.P., Verma, A.N. and Lodhi, G.P.1992. Larval and pupal population of Chilo partellus 

(Swin.) in different sorghum plant parts at crop harvest and moth emergence during offseason. 

Crop Res. 5 (2) : 359-362. 

144


LOSSES DUE TO INSECT-PESTS IN POTATO 

R. S. Chandel and Mandeep Pathania 



Potato is vulnerable to attack of pests, both in fields as well as in stores. A great 

diversity of pests attacking potato exists in India due to varying agro climatic conditions. 

These pests damage the potato crop by feeding on leaves, thus reducing photosynthetic 

efficiency, by attacking the stems thus weakening the plant, inhibiting growth of potato 

tubers and by feeding on tubers. Accordingly, potato pests are grouped into soil pests, 

foliage feeders, sap feeders and storage pests, besides nematode pests are dealt separately. 

In potato seed production, the pests of greatest concern are usually the aphid vectors of 

potato viruses especially Myzus persicae (Sulzer). In ware production, the key pests may 

be insects which attack tubers, such as potato tuber moth, white grubs and cut worms. In 

some situations, foliage feeders such as noctuids and coccinellids are important. 

1. SOIL PESTS 

Cut worms : In India, Agrotis ipsilon (Hufn.), A. segetum (Schiff.), A. flammatra Schiff., 

A interacta Wlk., and A. spinifera Hb. occur on potato. Greasy cut worm, Agrotis ipsilon 

(Hufn.) is generally a cool climate pest active from October onwards in plains and migrates 

to hills in summer.Surface cut worm, Agrotis spinifera Hb. occurs in Punjab, Bihar, Andhra 

Pradesh and Karnataka. Moths appear in August and peak population is found in September 

which gradually declines during October – November. Larvae feed on leaves, stem and 

tubers destructive at seedling stage during dry period when potato vines are quite tender. 

Tuber damage does not occur in rainy season crop, but larvae inflict considerable tuber 

damage in spring crop. In plains, it is active from October onwards and with onset of summer, 

it migrates to hilly regions. The larvae feed voraciously and cut potato plants in early stage 

of the crop growth. The plants are eaten off just above, or at short distance below the soil 

surface. In certain cases entire row of plants is cut. Tuber damage is manifested in the form 

of deep holes. The peak activity is found during May-June in Shimla hills. 

White grubs : White grubs are most destructive and troublesome soil insects, threatening 

potato production in hilly states. These white grubs are present in the soil at a depth of 5 – 

20 cms during the crop season. Large holes are made in the tubers which ultimately may be 

entirely transversed by wide deep mines (Chandel et al., 1995). In India, 20 species of white 

grubs have been reported causing damage to potato. Out of these, Brahmina coriacea (Hope) 

and Holotrichia longipennis (Blanchard) are most destructive, threatening potato production 

in hilly states. Holotrichia serrata (Fab) damages potato in Karnataka (Misra and Chandel 

2003). All the requirements of the life cycle of these beetles except mating and feeding are 

met with underground. 

Termites and Ants : Several species of termites such as Microtermes obesi (Holmgren), 

Odontotermes obesus (Rambur) and Eromotermes spp. have been reported damaging potato 

crop especially in sandy soil (Chandel and Chandla, 2003). The worker caste of termites is 

responsible for the damage by making deep holes. The termites feed on roots and tubers. 

145

The tubers become hollow and are often filled with soil and the leaves of such plants start 

yellowing and wilting and ultimately dry up. 

Red ants, Dorylus orientalis Westwood and D. labiatus Shuckard have termite like habit 

of attacking plants underground. The pest damages potato stem and tubers by making holes. 

Severely damaged plants show wilting during bright sunshine and finally plants dry up. 

2. STORAGE PESTS 

Potato tuber moth : Potato tuber moth, Phthorimaea operculella (Zeller) is a serious 

pest of stored potato tubers. The damaging stage of the pest is larva which feeds on potato 

foliage and attack tubers in the field before and shortly after harvesting. The infestation of 

PTM starts in the field on leaves and acts as an initial source of infestation. Moths emerge 

from over-wintering larvae in early spring and lay eggs, chiefly on underside of leaves or 

upon exposed tubers. 

3. LEAF EATING INSTECTS 

Hadda beetles : Epilachna beetles and its grubs form important pests of potato. The 

two types of Epilachna beetles commonly found all over India are the 12 spotted (Epilachna 

ocellata Redt.) and 28 spotted beetles (Epilachna vigntioctopunctata Fab.). The former is 

generally found in higher hills and later is, however, restricted to mid hills or plains. The 

damage is caused by the adult and grubs feeding on leaf tissues and skeletonizing the 

leaves.The grubs eat out somewhat regular areas, leaving slender parallel strips and uneaten 

portion between them, giving the plants a characteristic lace like skeletonized appearance. 

When abundant, the plants are shredded and dried out so that they die within a month after 

the attack begins, often before crop is matured. 

Leaf eating caterpillars : Several leaf eating caterpillars such as semiloopers, Plusia 

orichalcea (F.); tobacco caterpillar, Spodoptera litura (Hb); gram pod borer, Helicoverpa 

armigera (Hb.) and Bihar hairy caterpillar, Spilosoma obliqua Walk. have been reported to 

feed on potato foliage from different regions of the country. Of these, H. armigera and P. 

orichalcea are quite important. In plains, caterpillars of H. armigera migrate from chickpea 

to potato in the spring season and feeds on potato foliage. In hilly areas, the moths appear 

in large numbers by the end of March on ornamental plants and females lay eggs singly on 

the lower side of leaves. On hatching, the caterpillars feed on potato foliage. P. orichalcea 

caterpillars cause severe damage to foliage in the summer potato crop in Meghalaya and to 

spring crop in Punjab and Himachal Pradesh. 

4. SAP SUCKING INSECTS 

Green peach aphid, Myzus persicae Sulzer : The primary concern with aphids is 

usually their role as virus vectors in potato seed production. The cosmopolitan aphid, M. 

persicae is sufficiently important a pest on potatoes and other crops. In M. persicae only 

eggs are produced by sexual reproduction whereas all subsequent reproduction is viviparous 

and parthenogenetic. The aphids have both winged and wingless forms. Wingless forms are 

predominant on potato during most part of the year. M. persicae over winter as eggs on a 

very restricted number of primary host species, often woody plants (Peach etc.). In spring, 

wingless aphids called stem mothers hatch from eggs, feed on the primary host, mature and 

produce young ones asexually. Offspring’s of stem mothers are generally all wingless. 

146

Leaf hoppers : In India, Amrasca biguttula biguttala and Empoasca devastans are the 

major species of leaf hoppers. Prolonged feeding by the adults and nymphs causes a condition 

known as “hopper burn” i.e. brown triangular lesion at the tip of the leaf. Toxins in the saliva 

of potato leaf hopper induce swelling of cells, which eventually crushes the phloem. There 

is depletion of plant reserves due to increase in plant respiration subjected to hopper attack. 

Nymphal period is12 days. New adults begin laying eggs when they are 6 days old and 

usually complete 2-4 generations in a year. 

Thrips : Thrips are the vectors of tospo viruses causing stem necrosis in potato. Seven 

species of thrips are associated with potato. Of these, Thrips palmi Kamy, Scirtothrips 

dorsalis Hood, Coleothrips collaris Priesner and Haplothrips sp. are important. Both adults 

and nymphs scrap the epidermal tissues of leaves usually near the tips and rasp the oozing 

sap. The surface of leaves becomes whitened and somewhat flecked in appearance. The 

tips of leaves wither, curl up, and die. The under side of leaves will be found spotted with 

small brownish-black specks. They rasp and puncture the surface of the leaf with their 

stabber like mouth parts and swallow the sap, together with bits of leaf tissue. Under 

conditions of high incidence, the whole field gives a “dry blight” appearance where most of 

the infected plants have dry leaves hanging on blighted stems. 

Whitefly, Bemisia tabaci : The infestation of B. tabaci is more on early potato crop 

planted in September. Maximum population on potato occurs in November and there is 

sharp decline in white fly population by December. Both nymphs and adults suck the sap 

usually from ventral surface of leaves and devitalize the plants. In addition, they also act as 

a vector mainly for potato Gemini viruses in plains. The affected plants remain stunted and 

their leaves show distinct upward or downward curling. Leaves of affected plants show dark 

green veins as compared to normal translucent veins of healthy plants. 

5. NON-INSECT PESTS 

Mite, Polyphagotarsonemus latus : This “broad mite” cause tambera in potato. Both 

nymphs and adult damage the crop. The margins of fresh leaves are cupped and distorted 

with corky area between main veins on underside of the leaves. There are characteristic 

copper colour deposits on the lower side of leaves. Under severe mite attack, the infested 

leaves dry up resulting into ultimate death of plant that can be easily spotted in the infested 

fields due to their bronze colour. The peak activity of the mites occurs in August when sun 

shine is bright.The entire life cycle is completed in 5-8 days. 


Anonymous,2000. Package of Practices For Rabi Crops. Directorate of Extension 

Education,HPKV Palampur (Himachal Pradesh). 

Butani, D.K. and Jotwani, M.G. 1984. Insects in Vegetables. Colour Publications, Mumbai: 

356 p. 

Chandel, R.S.; Chandla, V.K. and Sharma, A. 2003. Population dynamics of potato white 

grubs in Shimla hills. J. Indian Potato Assoc. 30 (1-2) : 151-152. 

Chandel, R.S.; Chandla, V.K. and Singh, B.P. 2005. Potato tuber moth – Phthorimaea 

operculella (Zeller). Tech. Bull. No.65, CPRI, Shimla. 

147

Chandel, R.S., Gupta, P.R. and Chander, R. 1995. Behaviour and biology of the defoliating 

beetle, Brahmina coriacea (Hope) (Coleoptera: Scarabaeidae) inHimachal Pradesh. 

J. Soil. Biol. Ecol., 15 (1) : 82 - 89. 

Chandel, R.S. and Kashyap N.P. 1997. About white grubs and their management. Farmer 

and Parliament, XXXVII (10) : 29–30. 

Chandel, R.S., Kumar, Rajnish and Kashyap, N.P. 2001. Bioecology of potato tuber moth, 

Phthorimaea operculella Zeller in mid hills of Himachal Pradesh. J. ent. Res., 25 (3) : 

195 – 2003. 

Chandel, R.S., Kumar, Rajnish and Mehta, P.K. 2001. Monitoring of incidence of potato 

tuber moth, Phthorimaea operculella Zeller in mid hills of Himachal Pradesh. Pest mgnt. 

Econ. Zoo. 9 : 71-77. 

Chandla, V.K.; Khurana, S.M. Paul and Garg, I.D. 2004. Aphids, their importance, monitoring 

and management in seed potato crop. Tech. Bull. No. 61, CPRI, Shimla: 12 p. 

Khurana, S.M. Paul, Bhale, Usha and Garg, I.D. 2001. Stem Necrosis disease of potato. 

Tech. Bull. No. 54, CPRI, Shimla. 

Misra, S.S. and Chandel, R.S. 2003. Potato white grubs in India. Tech. Bull. No. 60, 

CPRI, Shimla. 

148


DUE TO INSECT-PESTS IN OILSEED CROPS 

S. P. Singh 


CCS Haryana Agricultural University, Hisar-125004, India 

In India, major oilseed crops are rapeseed-mustard, sunflower, linseed, groundnut castor 

and sesame, which played an important role in agriculture economy and contributed 

significantly to yellow revolution of the country. Insect pests are one of the major constraints 

in increasing and stabilizing the production and productivity of oilseed crops. Pest wise 

information about diagnostic symptoms of damage and assessment due to losses of major 

pests infesting oilseed crops are described below. 

I. BRASSICA CROPS (Rapeseed-mustard) 

Mustard aphid, Lipaphis erysimi 

Damage : The damage is caused by both the nymphs and adults that are feeding in 

large numbers often covering the entire surface of flower buds, shoots and pods resulting in 

chlorophyll reduction causing pale and curved leaves. Both the nymphs and adults suck cell 

sap from leaves, stems, inflorescence and the developing pods. Due to the very high population 

of the pest, the vitality of plants is greatly reduced or even plant may die. The leaves acquire 

a curly appearance, the flowers fail to form pods and the developing pods do not produce 

healthy seeds. The honeydew excreted by the aphids provides congenial conditions for the 

growth of sooty mould on the plant. In case of severe infestation the crop yield may be 

reduced by even 80 per cent or more. 

Painted bug, Bagrada hilaris 

Damage : The damage is caused by both nymphs and adults. The painted bug appears 

at two stages of crop growth i.e. seedling and mature / harvesting and many times infestation 

is carried even to threshing floor. Both nymphs and adults suck cell sap from the leaves and 

developing pods, which gradually wilt and dry up. Severe attack at seedling stage may even 

kill the plants. The nymphs and adult bugs also excrete a sort of resinous material, which 

spoils the pods. 

Mustard sawfly, Athalia lugens 

Damage : It is a serious pest of all crucifers at the seedling stage. The grubs alone are 

destructive. They bite holes into leaves preferring the young growth and skeletonize the 

leaves completely. Some times, even the epidermis of the shoot is eaten up. The older 

plants, when attacked, do not bear seed. 

II. SUNFLOWER 

Cutworms, Agrotis spp. 

Cutworm damage is caused by larval feeding and normally consists of seedlings being 

cut off from 1 inch (25 mm) below the soil surface to as much as 1 to 2 inches (25 to 50 mm) 

above the soil surface. Young leaves also may be severely chewed from cutworms (notably 

the dark sided cutworm) climbing up to feed on the plant foliage. Most cutworms feed at 

night. During the daytime, cutworms usually are found just beneath the soil surface near the 

149

ase of recently damaged plants. Wilted or dead plants frequently indicate the presence of 

cutworms. Cut plants may dry and blow away, leaving bare patches in the field as evidence 

of cutworm infestations. 

Head borer, Helicoverpa armigera 

The head or capitulum borer causes considerable damage to developing grains in the 

head capsule. The young larvae first attack the tender parts like bracts and petals, and later 

on shift to reproductive parts of the flower heads. Bigger larvae mostly feed on seeds by 

making tunnels in the body of the flower heads and often remain concealed. They may also 

shift to the backside of the heads and even leaves, and feeding may continue upto maturity. 

Star bud stage of the crop is most vulnerable and suffers maximum yield loss. 

III. GROUNDNUT 

Ground aphid, Aphis craccivora 

Damage : Nymphs and adults suck sap from the tender growing shoots, flowers, and 

pegs, causing stunting and distortion of the foliage and stems. When the attack occurs at 

the time of flowering and pod formation, the yield reduces considerably. Infestation on the 

groundnut crop usually occurs 4-6 weeks after sowing. They secrete a sticky fluid (honeydew) 

on the plant, which is turned black by a fungus. The blackened honeydew is called sooty 

mould. 

White grub, Holotrichia consanguinea 

Damage : The grubs eat away the nodules, the fine rootlets and may also girdle the 

main root, ultimately killing the plants. The damage becomes evident only when the entire 

plant dries up due to the grubs feeding on fibrous roots.At night, the beetles feed on foliage 

and may completely defoliate even trees like neem (Azadirachta indica) and banyan (Ficus 

bengalensis) etc. 

IV. CASTOR 

Castor hairy caterpillar, Euproctis lunata 

Damage : Devastating pest of rain-fed ground nut crop, also feeding on sorghum, cotton, 

castor etc. Larvae feed gregariously by scraping the under surface of tender leaflets leaving 

the upper epidermal layer intact looks like thin papery. Caterpillars feed on the leaves of 

various host plants and in case of severe infestation, they may cause complete defoliation. 

The attacked plants remain stunted and produce very little seed. 

V. SESAME 

Til leaf and pod caterpillar, Antigastra catalaunalis 

Damage : Leaf roller/capsule borer, Antigastra catalaunalis Dup. is a major and 

serious pest of sesame crop damaging the crop from seedling to flower and capsule stages 

at larval stages. At initial stage it webs the upper portion of plant and feed there upon, 

whereas at flowering stage it feeds on the flowers and at capsule stage it bores into the 

capsules. Thus, 20 to 50 per cent losses in yield are caused. One to three larvae are enough 

to denude a fully grown plant within 24 to 48 hours. Young caterpillars feed on leaves. They 

also bore into the shoots, flowers, buds and pods. An early attack kills the whole plant, but 

infestation of the shoots at a later stage hampers further growth and flowering. 

150

VI. LINSEED 

Linseed gall-midge, Dasineura lini 

This insect appears as a serious pest of linseed in some parts of India. including Andhra 

Pradesh, Madhya Pradesh, Bihar, Uttar Pradesh, Delhi and Punjab. The adult is small delicate, 

mosquito like orange coloured insect. 

Damage : The damage is caused by maggots, which feed on the flower buds and prevent 

their proper opening. Consequently the seed dose not set properly. Due to their feeding, 

galls are produced and there is no pod formation. The incidence of this pest goes up to 20 

per cent Damage is the result of feeding by maggots on buds and flowers. Consequently, 

no pod-formation takes place. 

ASSESSMENT OF LOSSES IN OILSEEDS DUE TO INSECT PESTS 

To estimate the yield losses due to insect pests in rapeseed mustard two sets of 

conditions, protected and un-protected need to be maintained by spraying the recommended 

insecticide at economic threshold under field conditions. 

The population of mustard aphid can be recorded from 10 cm top twig of 10 randomly 

selected and tagged plants in each plot, before and after spay of oxydemeton-methyl 0.025%. 

Finally crop yield from both the sets (protected and un-protected) for each genotype per 

replicate was recorded. The per cent avoidable yield loss may be calculated according as 

per the following formula. 

Mean yield under protected set : A 

Mean yield under un-protected set : B 

A-B 

Per cent avoidable loss =–––––– x 100 

A 

The avoidable yield losses due to aphid infestation in three different Brassica genotypes 

were determined in terms of seed yield varied from 10.9 to 15.3 per cent, it being the lowest 

(10.9%) in T-27 and highest (15.3%) in RH-8812. Irrespective of the genotypes the crop 

under protected conditions (Oxydemeton-methyl 0.025%) gave 14.0% higher yield than unprotected 

conditions (Dinesh Kumar, 2008). 

According to Dhaliwal et al. (2004), rapeseed-mustard in India generally suffers a 30 per 

cent yield loss due to in-sect pests. This loss amounts to 27 300 million of indian rupees, 

annually (approximately 600 million US dollars). Losses in yield were too high as B. carinata 

sustained 81.86% losses followed by B. juncea (77.25%) and B. napus (75.06%). Highest 

losses (56.84 to 78.29%) were observed in number of pods per plant among the yield 

components. (Ali et al., 2003). The loss in seed yield, due to mustard aphid and cabbage 

caterpillar, varied from 6.5 to 26.4 per cent. E. sativa suffered the least loss in seed yield 

and harboured the minimum population of mustard aphid (2.1 aphids/plant) and cabbage 

caterpillar (2.4 larvae/plant). On the other hand, B. carinata was highly susceptible to the 

cabbage caterpillar (26.2 larvae/plant) and suffered the maximum yield loss (26.4%). Aphid, 

Lipahis eyrsimi Kalt., causes 10-90% losses in yield in India to these crops depending upon 

severity of damage and crop stage (Rana, 2005). 

151


Bakhetia, D.R.C. and Sekhon, B.S. 1989. Insect-pests and their management in rapeseedmustard. 

J. Oilseeds Res. 6 (2) : 269-299. 

Chander, S. and Phadke, K.G. 1994. Economic injury levels of rapeseed aphid, Lipaphis 

erysimi determined on natural infestation and after different insecticides treatments. 

Intern. J. Pest Manag. 40 : 107-110. 

Kalra, V.K., Gupta, D.S. and Yadav, T.P. 1983. Effect of cultural practices and aphid infestation 

on seed yield and its component taits in Brassica juncea (L.) Czern and Coss. Haryana 

agric. Univ. J. Res. 13 : 115-120. 

Nain, Rohit, Dashad, S.S. and Singh, S.P. 2009. Relative efficacy of newer insecticides 

against pod borer, Helicoverpa armigera (Hubner) infesting sunflower crop. Proc. National 

Symposium on role of pesticide application technology in crop protection : towards 

sustainability in agriculture. 20-22 January, 2008 organised by Institute of Pesticide 

Formulation Technology,Gurgaon, India.pp. 61-62 

Singh, H.1982. Studies on insect-pest complex in Brassica campestris L. var. brown ‘sarson’. 

Thesis, Doctor of Philosophy, Entomology, submitted to Haryana Agricultural University, 

Hisar, 192 pp. 

Singh, S.P. 2009. Population dynamics and monitoring techniques for aphid in rapeseed 

mustard. Proc. Advanced Training Course on recent advances in pest population dynamics 

and monitoring techniques. 17th February to 9 th March, 2009, organized by Department 

of Entomology, CCS Haryana Agricultural University, Hisar, India. pp. 95-98 

Singh, S.P. 2009. Insect pest management in oilseed crops. Indian Farming 58 (7) : 29-33. 

152


DUE TO INSECT-PESTS IN SPICES 

Yogesh Kumar 



Spices are well known for their aroma and are used for various preparations of food. 

Certain spices are also used as medicines. India, a house of spices, is the largest producer, 

consumer and exporter of spices in the world accounting for about 35 per cent of the global 

trade. The spices are attacked by a wide range of insect-pests, like hemepterans (aphids, 

leafhoppers and whiteflies), coleopterans (beetles and weevils), dipteran flies, lepidopterans, 

thysanopterans (thrips) and hymenopterans (midge flies) both under field and storage 

conditions. The loss due the insect-pests in the field and stores has been estimated varying 

from 5 per cent to almost complete. Hence, it becomes essential to know the diagnostic 

symptoms, detection of infestation, crop loss assessments of different insect-pests so as 

to develop the management strategies and avoid losses. The available information on these 

aspects are summarized in this chapter. 

ONION AND GARLIC 

Onion thrips (Thrips tabaci) : Nymphs as well as adults damage the crop lacerate the 

leaf tissues, suck the sap oozing out of the leaf tissues forming silvery white blotches which 

later on turn white brown and the tip of the leaf dries up. The damaged plants remain stunted 

having twisted leaves. Due to heavy infestation of this pest, crop gives a burut look. The 

seed yield and it’s viability is affected adversely. 

Leaf miner (Chromatomyia horticola) : Adult of this pest is a small black fly, female 

of which lay eggs in the leaf tissues. After hatching the maggot starts feeding in the leaf by 

making a white serpentine mine in the leaf tissues. The maggot is about 1-2 mm long, green 

in colour and pupates in the mine itself. 

Aphids (Myzus persicae) : They are green or reddish brown in colour and suck cell sap 

from the leaves, and weaken the plants. This pest is minor but can cause great losses by 

acting as vector of viral diseases. 

Onion maggot (Hylemia = Delia antique) : The adult fly is grey and resembles housefly 

but smaller in size. Female lay eggs in the soil near the base of the plant or on the older 

leaves. The eggs hatch in one week and the maggot is white legless larvae. Maggots after 

hatching crawl to the roots and bulb and feed on them and also on the tender portion of the 

plant. Plants due to damage becomes yellow to brown which later dry away and the bulb 

may get rotten during heavy infestation. 

Helicoverpa armigera : The larva feeds on leaves, inflorescence and developing grains 

in onion. Sometimes this borer can cause heavy loss in seed crop. 

Spodoptera exigua : Female of this moth lays eggs on the leaf surface. The larva after 

hatching enter inside the hollow leaves and feed on them. The damaged leaves droop down. 

Sometimes many larva can be seen inside a hollow leaf after splitting. 

153

CHILLI 

Cutworm (Agrotis ipsilon) : Larva, the damaging stage is green in colour and nocturnal. 

During day it hide in the soil and during night comes out and cut the young plants at the 

ground level and drags it away from the original place. Larva pupates in soil. Total life cycle 

is completed in about 35 days. 

Thrips and aphid : As in onion and garlic. 

Spodoptera litura : Its larva is a foliage feeder and makes holes in the leaves. 

Helicoverpa armigera : It’s larva feeds on the fruit and developing seeds inside the 

green chillies causing considerable loss of fruits and seed yield. 

Blister beetle (Mylabris pustulata) : Polyphagous beetle in chilli feeds on green fruits 

and cause nominal loss in yield. 

TURMERIC AND GINGER : The major insect-pests damaging the crop are mentioned 

below : 

Shoot borer (Conogethes punctiferalis) : The larva bores into the preduo stem and the 

frass exrudes out of bore hole. It feeds on growing shoot resulting in yellowing and drying of 

shoot. Dead heart formation of the central shoot is main symptom of infestation. 

Leaf roller (Udaspes folus) : The larva cuts and folds the leaf, and feeds within. Plant 

growth is stunted due to weakness. 

Mealy bugs (Aspidiella curcumae, Stephanitis typica) : Suck the sap from leaves of 

turmeric, Pentalonia nigroniervasa feed on giner). 

Thrips : Damage same as in onion and garlic. During severe infestation the development 

of rhizome is greatly reduced. 

Rhizome maggots (Calobata sp., Chalcidomyia atricornis) : Various species of dipteran 

maggots are associated with these two crops. The maggots bore into rhizomes and feed on 

them. Damaged rhizomes are decayed. Losses has been assessed upto 37 per cent. 

Whitegrub (Holotrichia sp.) : This grub feed on the tender rhizomes or at the base of 

pseudo stem of turmeric. 

CORIANDER, FENNEL, CUMIN, AJWAN AND FENUGREEK : 

Coriander aphid (Hyadaphis coriandri) : Both adults and nymphs suck the cell sap 

from leaves, stem and inflorescence. The attacked portion becomes sticky and damaged 

umbel gives burnt appearance. Seed setting in umbel may be completely absent or if formed 

seeds are of poor quality. Losses due to this pest has been reported upto 90 per cent or 

more (Mittal and Butani, 1994). Other species of aphid, Hyadaphis foeniculi is a pest of 

coriander and fennel. 

Green peach aphid (Myzus persicae) : This is a pest of coriander, fenugreek and 

cumin. 

Seed midge (Systotle albipennis) : It is a serious pest of coriander, fennel, cumin and 

ajawan. The adult fly lays eggs in developing coriander or fennel. After hatching the young 

larva feed inside the seed and pupates there. The adults emerges out by making a round 

hole in the seed in the stores. Though the weight loss is low but qualitative loss is heavy 

because of non acceptability by consumers. 

154

Whitefly (Bemisia tabaci) : is a polyphagous pest and suck the cell sap. They also 

secret honey dew on which black sooty mould grows which interferes with photosynthesis. 

Leafhoppers (Balclutha sp.) : Suck the cell sap from leaves of Ajwan, Zygindia 

behrinensis, Empoasca spinosa attack the fenugreek and both adults and nymphs suck the 

cell sap from underside of leaves. 

INSECT-PESTS OF STORED SPICES 

Surviving field eggs and larvae commonly pass to the store to the processor, pantries 

and finally to food items which remain virtually unnoticed. However, about 300 different species 

of stored product pests have been encountered with only about 18 spices of primary economic 

importance. Based on feeding behaviour insects can be grouped into two categories viz. 

external feeders which complete all the life stages outside the grain and internal feeders 

which complete all immature stages inside the grain. The major insect-pests of stored spices 

are mentioned below:- 

Cigarette beetle (Lasioderma serricorne) : It infests chillies, turmeric, dry ginger and 

coriander both whole grains and processed spices. It is a tortoise shaped dark brown shining 

beetle. Grubs are cream coloured crescrent shaped larvae. The female beetle lays eggs 

loosely or singly on dried spices their seeds or in their powder. Both beetles and adults 

cause damage. They make holes in the seeds and in powder the grubs stick the powder 

around their body and make balls and feed inside the powder boll. The infested seeds or 

powdered spices are unhygienic and not worth consuming. 

Moth ; (Ephestia cautella) : It is small moth. Moth lays eggs in the powdered spices. 

Larva is the damaging stage which feed on the processed powder and make web or silken 

cocoon for pupation. They contaminate the spice with their exuvae and faeces and the produce 

becomes not worth consuming. 

Drug beetle (Stegobium paniceum) : It is a pest in coriander, fennel and cumin both 

whole grains and processed spices. Both adult and grubs cause damage. Female beetle 

lays eggs singly and loosely among the food material. Newly hatched grubs feed by making 

tunnels in the food material by cutting small holes. Adult beetle is small stout 3-4 mm long 

with light dull brown colour. Total life cycle is completed in 6-8 weeks. 

Sawtoothed grain beetle (Oryzaephilus surinamensis) and Merchant grain beetle 

(O. mercator) : These beetles probably can not attack whole undamaged grains, so they 

may be associated with other whole grain pests and feed on the seeds damaged by other 

pests. 

Rust red flour beetle (Tribolium castaneum) and confused flour beetle (T. confusum) 

: They feed on seeds of spices and powdered spices. They produce secretions that 

contaminate the material giving it a disagreeable odor and taste. 

MONITORING AND ASSESSMENT OF LOSSES CAUSED BY INSECT-PESTS IN STORED 

OR PROCESSED SPICES 

Regular and timely inspection of insect-pests populations must be done to manage the 

populations to avoid to cause damage in stored or processed spices. Generally, the 

inspections are necessary once a fortnight during rainy season and once a month during 

other seasons. Various methods of detection of pest populations and for assessment of 

losses are given below. 

155

Sieving : Sieving the seeds on 10 to 16 mesh sieves make the insects present in the 

seed mass get collected below sieve. 

Disturbing of stocks : Disturbing of stacks or bulk surfaces by moving a long stick over 

vertical stack surfaces or surfaces may be struck to disturb resting adult insects. 

Agitation of sacks : Agitation of sacks by throwing bags of seeds or processed spices 

up and down several times and then leaving them for 10 to 20 min. will make the adult 

insects to walk out on the bag surface even when the population is quite low. 

Feeling temperature in bulk store : Walking over a bulk of grain with bare feet indicates 

its condition. If it is cool and free blowing then the bulk store is free from insect populations. 

If there is a hot spot or a fairly solid patch is found that means high dust content or insect 

populations. 

Traps : Different types of traps have been developed (a) probe trap (b) pit fall traps which 

are put in the storage bins. The insects are collected in these traps and their populations 

can be counted. 

Dead insects : When a residual insecticide has been applied to a surface and dead 

insects continue to accumulate there, then this is usually an indication of live insects in the 

area. 

Stimulative sprays : Sprays which stimulate insect activity (pyrethrum insecticide) are 

useful in exposing hidden insects present in crevices specially in vehicles which are to be 

used to carry the produce. 

Powdered spots : Presence of powdered spots outside the stored bags and skin cast 

by the larvae indicate the insect infestation in grain masses. 

HIDDEN INFESTATION 

Density method : Involves the use of 2 solutions of different specific gravity. The seeds 

are immersed in sodium silicate the methyl chloroform and a 3 layers separation occurs. 

The non-infested seeds sink to the bottom, the infested seeds float and light seeds including 

those infested by early stages of insects hang in the line of separation between the two 

fluids. 

Gelatinization : In this method seeds are boiled for 10 min. in 10 per cent solution of 

sodium hydroxide. The boiling makes the seeds translucent and the presence of internal 

infestation is indicated. 

Floatation method : Cleaned seeds are coarsely grounded and then soaked in a wateralcohol 

solution or in boiling water and finally mixed with gasoline or mineral oil. The insects 

float with the oil layer. 

Spctrophotometric analysis : Spectrophotometric analysis of dihydroxyphenol occurring 

in insect cuticle produce certain dyes when these react with dichloroquinone chlorimide. 

Staining : Acid fuchsin stain is prepared by mixing 50 ml glacial acetic acid in 950 ml of 

distilled water and adding 0.5g acid fuchsin. Samples of seeds are soaked in warm water for 

5 min. and then immersed in the stain for 2-5 minutes. Finally the excess stain is removed 

by washing with water. By this method egg plugs of weevils are stained bright cherry red and 

feeding punctures including mechanical injuries in light pink (Frankenfeld, 1948). 

156

Aural method : Insect infestation can be noticed quantatively with the help of a special 

instrument known as Acoustic apparatus. Mechanical vibration produced by the insects, is 

picked up by a receiver and converted into electric signals. After amplifying several thousand 

times, the signal is conveyed to a transmitter or head phone. 

Ninhydrin colour reaction : This method is based on a chemical indicator technique in 

which the body fluid of the insects (free amino acids of coelomic fluids of insects) produce a 

colour reaction (purple spots) with ninhydrin impregnated filter paper (0.7% solution in 

acetone). An instrument called Ashman Simon infestation detection has also been 

manufactured for this purpose. 

X-ray radiographic method : This method was suggested by Milner et al. (1950) but 

recently the use of Polaroid radiographic media has been suggested. 

Carbondioxide method : In this method, sample free from moving insects is incubated 

for 24h at 25 o C. Level of 0.3 per cent CO 2 at 14% moisture content indicates that the sample 

is insect free, whereas a level between 0.5 to 1.0 per cent indicated that the sample is unfit 

for long storage. 


Koya, K.M.A., Balakrishnan, R., Devanshayam, S. and Banerjee, S.K. 1986. A sequential 

sampling strategy for the control of shoot borer (Dichocrosis punctiferalis Guen.) on 

ginger (Zingiber officinale Rosc.) in India. Tropical Pest Management 32 : 343-46. 

Mittal, V.P. and Butani, P.G. (1994). Pests of seed spices. In : Advances in Horticulture 

Vol.10. Plantation and Spice Crops Part-2 (1994) Eds. : K.L. Chadha and P. Rethinam. 

pp. 825-855. 

Frankenfeld, J.C. 1948. Staining methods for detecting weevil infestation on grain. USDA 

But. Ent. and PI Quarantine Cric. ET-256. pp. 4-Mimeographed. 

Milner, M., Lee, M.R. and Katz, R. 1950. Application of X-ray technique to the detection of 

internal insect infestation. J. econ. Ent. 43 : 933-35. 

157

REMOTE SENSING AND ITS APPLICATION 

IN PEST DAMAGE DIAGNOSIS 

1.0 Concept of Remote Sensing 

Ramesh S. Hooda 

Haryana Space Application Centre (HARSAC) 


Remote sensing is defined as the science and technology of obtaining information about 

an object without being in physical contact with it. Electromagnetic radiation, which is reflected 

or emitted from an object, is the usual source of remote sensing data. A device to detect the 

electromagnetic radiation reflected or emitted from an object is called a remote sensor” or 

“sensor”. Cameras or scanners are examples of remote sensors. A vehicle to carry the 

sensor is called a “platform”. Aircraft or satellites are used as platforms. Since Landsat-1, 

the first earth observation satellite was launched in 1972, remote sensing has become widely 

used. 

The characteristics of an object can be 

determined using reflected or emitted 

electro-magnetic radiation, from the object. 

Eeach object has a unique and different 

characteristic of reflection or emission due 

to its inherent chemical and physical 

characteristics. The concept of remote 

sensing is illustrated in figure 1. 

The electromagnetic radiations received from 

the sun are emitted or reflected by various 

objects on the earth. 

The reflected or emitted radiations are 

attenuated by the atmosphere and detected 

by the sensor fitted on a platform i.e. 

satellite or aircraft. The remote sensing data 

Fig. 1 Data collection by Remote Sensing 

received at the ground station is processed automatically by computer and/or manually 

interpreted by humans, and finally utilized in agriculture, land use, forestry, geology, hydrology, 

oceanography, meteorology, environment etc. 

2.0 Energy source and Radiation Principles 

The Electromagnetic Spectrum (EMS) is an array of electromagnetic radiation, which 

moves in the form of wave that are characterized by their wavelength or frequency. The EMS 

(fig. 2) has different regions characterized by wavelength and frequency of waves as described 

above. Visible light is only a part of the entire spectrum of electromagnetic radiations ranging 

from 0.4 to 0.7 ìm of wavelength to which our eyes are sensitive. Although names such as 

ultraviolet and microwave are generally assigned to regions of EMS for convenience, there is 

no clear-cut dividing line between one spectral region and the next. Besides the blue, green 

and red bands of the visible range, Infra-red (IR) and microwave portions of the spectrum are 

most commonly used in remote sensing. Within the IR portion the thermal IR energy is 

directly related to the sensation of heat, near and mi-IR energy are not. Based on the source 

of radiation, remote sensing technology can be divided into two classes namely passive 

158

emote sensing and active remote 

sensing. In passive technique, reflected or 

emitted electromagnetic radiation from 

natural source is measured. Most remote 

sensing programs utilize the sun’s energy, 

which is the predominant source of energy 

at earth’s surface. The black body radiation 

emitted by earth’s surface is also utilized 

in passive remote sensing. The 

instruments/sensors, which measure this 

kind of energy, are called passive sensors 

or radiometers. In active remote sensing, 

earth’s surface is illuminated by artificial 

man made radiation e.g. radar or Lidar. The 

instruments used in active remote sensing 

are called active sensors. 

3.0 Concept of signature 

Fig. 2. Electromagnetic spectrum and bands 

used in remote sensing 

The science of remote sensing is 

essentially built on the basis of signatures 

of objects. The knowledge of signature is 

used to identify the object, which is 

somewhat similar to identification of person 

on the basis of knowledge of his signature. 

In Remote Sensing, objects are identified 

based on the knowledge of spectral 

reflectance of object. This is called 

spectral signature. Fig. 3 shows the 

spectral reflectance of various objects in 

different wavelength regions. As water 

absorbs heavily in all the Fig. 3 

Reflectance properties of different objects 

wavelength regions, it shows very less 

Fig. 3. Spectral reflectance of different objects 

reflectance and thus appears black on the satellite image. The snow on the other hand 

reflects heavily in all the wavelength bands and looks white on the satellite image. In general, 

reflectance increases with wavelength and increases in the near infrared region. 

Vegetation shows a typically different reflectance characteristic. In the visible region, it 

absorbs in the blue and red regions due to the presence of chlorophyll and other leaf pigments. 

Green part of the light is reflected which gives the vegetation its green colour. The higher 

reflectance in the near IR region of EM radiation is caused by their internal cellular structure. 

The abundance of intercellular spaces in the mesophyll cells interspersed by the hydrated 

cell walls bring about sudden changes in the refractive index of the medium causing refraction 

of the infrared radiations. Presence of water leads to absorption of radiation at 1.45 and 1.95 

ìm. Reflectance of soil depends upon the chemical and physical properties of the soil like 

moisture content, organic matter, iron concentration, soil texture and surface roughness. 

Reflectance of soil gently increases from the visible to the near infrared. It may be observed 

that spectral reflectance is negatively related to moisture content. A sandy soil has high 

reflectance and clay soils tend to have a fairly diffuse reflectance. Soil organic matter tends 

to decrease the reflectance. 

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4.0 Multi-spectral Imaging 

As indicated above, different objects on the earth have different reflectance properties in 

different wavelength regions of the spectrum. Therefore, the objects can be better 

discriminated if the information by the remote sensing system is collected in different bands 

instead of the entire length of the spectrum. The reflective or emitted energy received from 

the entire length of the spectrum is called Panchromatic data whereas the data received 

by different receivers of the sensor in different bands is called Multi-spectral data. Multiband 

images are images sensed simultaneously from the same geometric vantage point but in 

different bands of the EM spectrum. Different types of sensors are designed to collect 

panchromatic and/ or multi-spectral data. The multi-spectral data of individual bands like 

blue, green, red or near infra-red (NIR) is depicted by the shades of gray. A coloured image 

can be prepared of the multi-spectral data by assigning three primary colours of blue, green 

and red to different bands and superimposing them. The best combination of multiband 

images for discriminating a given scene varies with the spectral response patterns of the 

objects of interest within that scene. Regardless of the number and wavelength bands of the 

images, only three bands are selected for viewing at one time, with one band displayed as 

blue, one band as green and one band as red. Figure 4 indicates the combination of bands 

and assigned colours to prepare True Colour Composite (TCC) or False Colour Composite 

(FCC) images. 

Fig. 4. Preparation of TCC and FCC 

Though TCC gives the actual colour image of the terrain but all the information contents 

of the data are not included in this because the IR band which has valuable information 

about vegetation is excluded. In order to enhance the capability of interpretation, normally 

red colour is assigned to NIR, green to red, and blue to green reflectance. The resultant 

product/ image is called False Colour Composite (FCC) because in this the colour in the 

image do not represent the actual colour of the object. These false colour of objects are at 

first confusing to the interpreter because of familiar colour of object is shown in ‘wrong’ 

colour. For example, vegetation, which is green, is seen as red in FCC. FCC is one of the 

powerful means of visualizing the effects of spectral properties beyond the range of human 

vision. Table color Discrimination based on Wavelengths of Spectral Reflectance (IRS) 

5.0 Resolution 

Resolution of a remote sensing system is defined as the ability of total system to render 

a sharply defined image. Three types of resolutions are important in providing a sharply 

defined image: spatial resolution, spectral resolution and radiometric resolution. In addition, 

temporal resolution of a remote sensing system provides ability of the system for repetitive 

coverage of the same area. Definition of these are given below: 

Spectral Resolution : Refers to bandwidth of electromagnetic wave band used in the 

sensing system. 

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Spatial Resolution : spatial resolution is the geometric resolution of sensing system 

i.e. ability to distinguish two closely spaced objects. In optical remote sensing, it is 

usually described by the Instantaneous Field of View (IFOV) i.e. the maximum angle of 

view in which a sensor can effectively detect electro-magnetic energy. 

Radiometric Resolution : refers to degree of sensitivity of a sensor to intensity 

variations. It is determined by the number of discrete levels into wich input signal is 

divided. 

Temporal Resolution : refers to repetitivity of sensor coverage on ground. It depends 

an orbital parameters and swath of the sensor system. 

6.0 Remote sensing satellite data reception in India 

The state-of-the-art along-track scanners onboard the satellites have an array of detectors 

called Charged Coupled Devices (CCDs). There are different array of CCDs corresponding to 

each band. Each CCD receives the reflected or emitted radiations from a fixed area of the 

ground, depending upon its spectral resolution, and converts it into an electric signal. Each 

electric signal is assigned a Digital Number (DN) value depending upon the intensity of the 

radiations being received. The information received from a specified ground area (i.e. 5.8 x 

5.8 m or 23.5 x 23.5 m) corresponding to the spatial resolution of the data becomes the 

smallest unit of the image and is called the Picture Element or Pixel. The DN values 

corresponding to each pixel are stored onboard the recorder of the satellite and whenever 

the satellite reaches within the reception limits of a ground reception station these values 

are transmitted to the ground station in the form of microwaves and the data is stored on 

High Density Digital Tapes. The digital images or hard copy paper prints are prepared at the 

data centre to supply to the users. Some radiometric and geometric corrections are made in 

the data before supplying it to the users. 

All the satellite data in India from our own and foreign satellites is received at Shadnagar 

reception centre (near Hyderabad) of National Remote Sensing Agency (NRSA) and achieved 

and supplied to the users by National Remote Sensing Agency Data Centre (NDC). The 

characteristics of different satellite data products supplied by NDC and their comparative 

prices are provided in Table 1. 

7.0 Remote Sensing for Crop Pest Damage Diagnosis 

Geographical Information Systems (GIS) and Global Positioning Systems (GPS) are 

currently being used for variable rate application of pesticides, herbicide and fertilizers in 

Precision Agriculture applications in the large farms of western countries on operational 

basis, but the comparatively lesser-used tools of Remote Sensing and Spatial Analyses can 

be of additional value in identifying pest damage. The tools has the potential to provide 

valuable information in an integrated pest management context, allowing for a complete 

understanding (via remote mapping or spatial modeling) of the spatial complexity of the 

abiotic and biotic characteristics of a field and its crops, and providing information about 

pests that are present, or likely to occur. 

7.1 Manifestation of disease in reflectance properties of plants 

Since the satellite remote sensing is based upon the detection of reflected EMRs from 

the object, any pest which supplies sufficient plant stress to significantly distort the 

reflectance signal is a candidate for detection by means of remote sensing. Distortions of 

reflectance characteristics of crop canopy may result from: 

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Table 1. Characteristics of satellite data available in India through NRSC, Hyderabad 

Satellite Sensor Spatial Repetitivity Scene Size 

(year launched) Resolution (m) (Days) (Sq.Km.) 

Indian satellites 

IRS 1A/1B LISS I 72.50 22 148x174 

(1988,1991) LISS II 36.25 22 74x87 

IRS 1C/1D LISS-III 23.5 24 141x141 

(1995, 1998) PAN 5.8 24 70x70 

WiFS 188.0 5 810x810 

Resourcesat (P6) L-IV Mono 5.8 5 70x70 

(2004) Mx 5.8 5 23x23 

LISS-III 23.5 24 141x141 

AWiFS 56.0 (Nadir) 5 740x740 

70.0 (End Pixel) 

Cartosat-I PAN 2.5 5 27.5x27.5 

Stereo Pair 2.5 (F/A) 5 27.5x27.5 

Foreign satellites 

NOAA I-M AVHRR/3 1100 Daily 2700x2700 

(USA, 1994-98) 

Landsat-7 ETM 30 16 185x185 

(USA, 1999) 

Spot-5 HRG–Mxl 10 Steerable 60x60 

(France, 2002) HRG-PAN 5 26 60x60 

IKONOS-1/2 PAN 1 3 11x11 

(1999, 2001) Mxl 4 4 11x11 

(Space Imagine) 

Quick Bird PAN 0.6 Steerable 16.5x16.5 

(Digital Globe, 01) Mxl 2.44 Steerable 16.5x16.5 

Feeding injury 

Foliage deposits from the end products of insect metabolism 

Secondarily from fungus growth on these products 

Feeding injury may consequently cause 

Discoloration of the foliage 

Geometric distortion of leaves 

Distortion in the general shape of the plant (e.g. tree crown) 

Defoliation 

Remote sensing may not be useful in situation where insects/pests don’t affect the crop 

foliage to alter its reflectance properties. For example, it was difficult to identify the Americal 

Boll Worm infected cotton crop in Northern India, as the bollworm affects only the boll of the 

crop and the leaves remain un-affected. 

7.2 Crop Stress Detection 

As indicated in figure 4 above, Red and Near Infra Red (NIR) reflectance of the plants 

exhibit opposite behavior. A healthy unstressed plant has very low red reflectance and very 

high NIR reflectance. But as the plant stress increases due to any reason (water, salinity, 

nutrient or pest) or as the plants senescence starts, the red reflectance starts increasing 

and the NIR decreases. This opposite behavior of vegetation has been exploited by some 

162

workers for developing vegetation indices which are indicative of the vigour or health of the 

crop. Some of the important crop stress indices are as under : 

Ratio Vegetation Index (RVI) R/ NIR 

Vegetation Index Number (VIN) NIR/ R 

Normalized Difference Vegetation Index (NDVI) NIR-R/ NIR+ R 

Transformed Vegetation Index (TVI) / NDVI + 0.5 

Perpendicular Vegetation Index (PVI) /(R – R ) s v 2 + (NIR – NIR ) s v 2 

An important point to be noted is that what is detected in remotely sensed imagery is 

not the water/ nutrient stress or disease /pest infestation per se rather the net effect of 

stress and environment on crop growth. It is the skill and keen observation of an interpreter 

and a prior information about the region under a study that allows the interpreter to ascribe 

the observed anomaly in the temporal chromatic profile to the cause. 

7.3 Red Edge Shift 

Rapid increase in reflection from the red to the near infrared is characteristic of vegetation 

and termed the “red-edge.” Vegetation absorbs most of the light in the visible part of the 

spectrum but is strongly reflective at wavelengths greater than 700 nm. There could be 

about 50% change in reflectance of different vegetations between 680 nm to 730 nm. This is 

an advantage to plants to avoid overheating during photosynthesis. The phenomenon accounts 

for the brightness of foliage in infrared photography. It is used in remote sensing to monitor 

plant activity and could be useful to detect light-harvesting organisms on distant planets. 

A shift in the Red Edge or change of slope of the red edge has been reported in diseased 

plants in the ground based studies. Fig. 5 indicate the change in the Fig. 5. Red-edge shift 

in diseased plant shape of the red edge in the necrotic and chloretic plant. 

7.4 Pre-Visual Detection of Plant Diseases 

Ground based studies using Ground Truth Radiometer (GTR) and Infra-Red Gun indicated 

the potential of detecting some of the diseases three to five days before visual symptoms 

became apparent. This was possible because some of these diseases effect the leaf structure 

and consequently the infra-red reflectance before the appearance of visual symptoms. 

However, these changes in the reflectance properties of the plant are too feeble to be detected 

by present day signals onboard the satellites. However, Infra-red imaging using aerial surveys 

have been found useful for this purpose. 

Pre-visual detection of onset of crop stress due to water and/or nutrient stress, diseases 

and insect attack is especially important when management options exist to alleviate the 

stress conditions before yield reduction occurs. Remote Sensing technique offers the 

advantage of integrating large samples of crop canopy in a short time. Multi-spectral sensor(s) 

carried on an aircraft/ spacecraft allows a rapid large area coverage with a resolution depend 

on sensors and altitude flown. In addition to this, R. S. technique offers periodic monitoring 

of crop development and it is important for efficient crop stress monitoring for : 

i. Early detection and timely warning of the onset of stress. 

ii. Recommendation of appropriate crop protection measures. 

iii. Evaluation of effectiveness of protection measures. 

iv. Evaluation of regional as well as national crop yield loss due to crop stress. 

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7.5 Hyper-Spectral Imaging for disease detection 

Hyper-Spectral Sensors collect data in number of 

bands in very narrow band widths of about 10 nm. This 

allows the detection of light in narrower wavelengths.. 

Although originally developed for mining and geology due 

to its ability to identify various minerals, hyper-spectral 

remote sensing is used in a wide array of real-life 

applications. This technology is continually becoming more 

available to the public, and has been used in a wide variety 

of ways. 

Hyper-spectral Imaging is different from multispectral 

imaging in the sense that multispectral data contains about 4-10 bands whereas the hyperspectral 

data contains hundreds of bands. Moreover, hyper-spectral data is a set of contiguous 

bands (usually by one sensor), whereas the multispectral is a set of optimally chosen spectral 

bands that are typically not contiguous and can be collected from multiple sensors. 

Hyper-spectral data has been indicated to be useful for detection of insect/ pest infestation 

in crops. Scientists from Space Applications Centre, Ahmedabad used hyper-spectral data 

based indices to detect sclerotinia disease in mustard crop. Various Disease-Water Stress 

Indices (DWSI), as under, were developed using various band data to correlate it with the 

disease score collected from the field: 

DWSI-1 : R /R 800 1600 

DWSI-2 : R /R 1660 550 

DWSI-3 : R /R 1660 680 

DWSI-4 : R /R 550 680 

DWSI-5 : (R -R )/(R +R ) 

800 550 1600 680 

As indicated in figure 6, DSWI-3 was found to be highly correlated with the disease 

score with a R2 Fig. 5. Reflectance pattern in relation 

to damage symptoms 

Fig. 6. Correlation of DWSI-3 with disease 

value of approximately 0.7. The study indicated a great potential of identifying 

pest infestation using hyper-spectral data and more of such studies are required to be taken 

up for various insect/ pest infestation in different crop. 

7.6 Locust Monitoring 

Locust incidence follows the natural rhythm of bioclimatic occurrence. The breeding 

(egg laying), completion of various stages of life cycle, maturity and mass flight / upsurge 

are determined by: favourable condition at ground segment (in terms of soil moisture, texture, 

surface hardness, salinity, temperature, vegetation type and density and foot print of rainfall 

on ground) and favourable condition in space segment (i.e. max. and min air temperature, 

humidity, sunshine hours, velocity and direction of temperature, humidity, sunshine hours, 

velocity and direction of wind vector, upper atmospheric circulation pattern like convergence 

zone). 

Some of the above information can be generated using remote sensing data and other 

can be collected from the ground. All this information can be integrated in GIS to develop a 

Spatial Decision Support System (SDSS) for locust monitoring. By interpreting optical and 

radar data, together with ground based intelligence, it evaluates various parameters which 

determine the risk of locust breeding and invasion. This enables locust control to be prioritized 

based upon uptodate and real time environmental conditions. This mechanism has been 

developed by Regional Remote Sensing Service Centre (ISRO), Jodhpur. 

164

USE OF ADVANCED COMPUTER TOOLS IN 

SCIENTIFIC PRESENTATIONS 

A. K. Chhabra 

Department of Plant Breeding, 

CCS Haryana Agricultural University, Hisar 125 004, Haryana, India 

The education of teachers and researchers must be adapted to present technology. 

Almost everyone in an institute is accustomed to the use of computers today at least for 

word processing. But there are very few education sites where they are taken beyond this 

point of computer usage. Although not everyone need to know programming, computer 

graphics, hypermedia and so on, they should at least be given some insight into the 

possibilities available with computers today. 

In this brief note about usage of modern computer skills in biological presentations 

would be discussed to benefit the trainees enabling them to make efficient use of the computer 

facilities they have at their home place. 

Person intended to learn presentation tools must have some idea about the following 

areas/software : 

Making presentations through PowerPoint (preferably XP or higher version) 

Word Processing (MS Word) 

Data feeding and processing (MS Excel) 

Scanning of picture and text (Scanner) 

Labeling of pictures (MS PowerPoint) 

Editing of pictures (Photoshop, Corel etc.) 

Creation of web pages (Front Page, MS Publisher etc.) 

Use of digital camera (floppy/card/) 

Creation of animated gifs (Animation Shop2) 

Preparing Electronic manuals (CD Writer) 

Using multimedia (Audio, Video accessories) 

Sound Recording (Mike & sound-proof room) 

Editing documentary movies (VCD Writer and editor) 

Use of internet and e-mails (Netscape, internet explorer etc.) 

Searching web for the topic of choice (Search Engines: Google, AltaVista etc.) 

Creation of Hyper-books (Online teaching/education) 

Creating Exercise Environment 

Creating interactive CD media 

Creative imagination 

VCD cutter etc. 

165

A Computer Aided Learning Package includes following stuff: 

EQUIPMENTS 

PIV Desktop Computer (Windows Vista Compatible is 

preferred), Scanner, Digital Camera, Web camera, LCD 

Projector, Projection screen and Multimedia 

Softwares 

Office XP or higher version, Windows 98 or above 

(preferably Win XP), Gif animator, Voice recorder, 

Superegoo,CD writing software (Nero), Video card, TV tuner 

card and Flash media player etc. 

Creation of presentation: 

Simple presentation (text only), Narrated Presentation, 

Hyper linked presentation, Hyper linking with MS office files, 

Hyper linking with Picture files, Hyper linking with Macromedia 

flash files, Hyper linking with Gif animations, Hyper linking 

with media files, Hyper linking within ppt files, Hyper linking LOGO PRESENT ON THE 

with internet files (online animated files), Autorun CDs and Web- COMPUTERS THAT ARE 

based browsable CDs. 

WINDOWS VISTA CAPABLE 

Microsoft has recently released a document which would give details on what exactly 

a PC requires to be Vista capable and what constitutes a Windows Vista Capable 

computer. However, a Window Vista Capable PC would mean that it can run the 

home edition of the Vista and would feature the Vista Logo (how kind of Microsoft!). 

So if you are going to go PC shopping very soon, you should check out the label 

which would read “Designed for Windows XP—Windows Vista Capable”. 

BRIEF DISCRIPTION ABOUT SOME SPECIALIZED SOFTWARES 

Macromedia Flash 

Originally a web animation tool, Macromedia Flash has quickly become a standard for 

creating a dynamic, interactive experience. The Flash authoring program can be used to 

create animations, games, websites, standalone modules, and also has audio and video 

capabilities. 

Macromedia Fireworks 

Macromedia Fireworks is an image-editing program geared specifically towards producing 

web images. It is often used to create JavaScript effects as well for the program will generate 

both JavaScript and html to handle different sorts of image interactions. 

Macromedia Dreamweaver 

With Macromedia Dreamweaver you can easily create both websites and web 

applications. Aside from a WYSIWYG editor, Dreamweaver also has extended hand-coding 

functionality and supports the new XHTML standard as well as many other scripting languages 

including Coldfusion, PHP, and ASP. 

Macromedia Freehand 

Comparable to Adobe Illustrator but with far fewer options. Macromedia Freehand is a 

vector illustration tool. Whereas Fireworks is Macromedia’s editor for bitmapped images, 

Freehand works in a total vector environment. 

166

Adobe Premiere 

Adobe Premiere is a video editing software package with the ability to layer, crossfade 

and effects. Voiceovers, environmental sounds, and music can be imported and mixed with 

Premiere’s limited audio support. With support for both digital and analog video capture and 

the ability to output in a number of different formats Premiere is one of the most widely used 

video editing applications available. 

Adobe Photoshop 

Adobe Photoshop is a near-perfect image editing tool. Photoshop can be used for both 

print and digital and has support for all major image formats. Far superior to Macromedia 

Fireworks, Photoshop is the best image editing application there is. 

Adobe Illustrator 

One of the major strengths of Adobe Illustrator is the extent to which it resembles 

Photoshop. As a vector-image editor, it shares the same relationship with Photoshop that 

Freehand has with Fireworks. While the Fireworks/Freehand combination is an excellent 

choice for trainees, those in need of more options and an overall deeper experience should 

go with Photoshop/Illustrator. 

Adobe Photoshop Elements 

A pared-down version of Adobe’s excellent Photoshop image editing software. While this 

program does retain many of the features of it’s parent, it is intended for light editing by 

those who might be confounded by the amount of options in Photoshop. Excellent for editing 

photographs. 

Adobe Acrobat 

Adobe Acrobat can be used to author the Portable Document Format [PDF] or convert 

other documents created in Microsoft Word or other word processing packages into PDF 

documents. The advantage of having a document in PDF format is that it can be read on any 

machine that has the Adobe Acrobat Reader installed [a free download] and it also retains 

the quality of the original document. 

Adobe GoLive 

Comparable to Macromedia Dreamweaver, Adobe GoLive is a website creation tool allowing 

both WYSIWYG and straight code editing capabilities. 

Adobe InDesign 

Adobe InDesign is a page layout software package similar in functionality to Microsoft 

Publisher and is used for print layout in the creation of brochures, pamphlets, and flyers. 

Adobe LiveMotion 

Adobe LiveMotion is similar to Macromedia Flash as it allows for the creation of animation 

and interactive content. 

Microsoft Word 

Part of the Microsoft office suite, Word is a word processing and document creation utility. 

Microsoft Access 

Part of the Microsoft Office suite, Access is a database creation and management utility. 

Microsoft Visio 

Microsoft Visio is used to map web site architectures. A great tool for taking a website 

apart visually in order to either get a grasp of how it works or to plan it’s reconstruction. 

167

Microsoft FrontPage 

Part of the Microsoft office suite, FrontPage is a website creation utility. While FrontPage 

can be compared to both macromedia, Dreamweaver and Adobe GoLive, it is definitely the 

poorest of the bunch. 

Microsoft Excel 

Part of the Microsoft office suite, a spreadsheet creation and management utility. 

Microsoft Publisher 

Microsoft publisher is primarily used for print layout in the creation of brochures, 

pamphlets, and flyers. 

Microsoft PowerPoint 

Part of the Microsoft office suite, PowerPoint is used to create slideshows for 

presentations. 

Scansoft Omnipage Pro 

Scansoft Omnipage Pro is an optical character recognition program with the ability to 

read scanned documents and translate the letter shapes from the scanned image into type 

to be used in a word processor. 

ELECTRONIC MANUALS : 

Electronic manual means information in the digital form that can be read on any PC 

having capability of retrieving the information written on the storage media (floppy/zip disc/ 

CD/Pen drive etc.). A demonstration of an electronic manual being prepared for UG and PG 

students of Plant Breeding will be given in the training. This manual can be used for various 

purposes: delivering lectures, seminars, publishing proceedings of seminar/symposia etc., 

Publishing high quality pictures in digital form saves resources and its distribution is faster 

than hard bound big books. 

Preparation of such manuals requires little knowledge of all the software listed above. 

Moreover, internet links can also be provided on the CD which can be directly accessed to 

get up to date information while being on the internet. 

INTERNET 

World Wide Web as an Aid to Search and Explore New Information of global 

Importance : The World Wide Web (www) is a big part of the Internet; to understand the 

World Wide Web, one first has to understand its home - the Internet. The Internet is the 

global “Network of Networks,” linking thousands of computer networks together allowing 

communication with millions of computer users and access to resources from around the 

world. The Internet is an enormous library or collection of libraries through which one can 

access information on any topic of concern. It doesn’t matter what type of computer is used 

for connection to the Internet, a virtually limitless wealth of resources is available for everyday 

use. The Internet and the World Wide Web are (or will soon become) most important 

components for a research institute, college or school. The use of the internet also provides 

opportunities for inquiry-based learning through search engines and specially designed sites 

to extract specific information. Various important scientific journals also offer such 

opportunities to their users. Internet is the largest province for researchers and academics 

in laboratories. Now, the Internet is everywhere, it is growing rapidly worldwide and has 

gained widespread popularity relatively recently. 

168

List of Search Engines Worldwide 

The search engines below are all excellent choices to start with when searching for 

information. 

Google: : http://www.google.com 

AllTheWeb.com (FAST) :http://www.alltheweb.com Yahoo 

: http://www.yahoo.com 

MSN Search : http://search.msn.com 

Lycos : http://www.lycos.com 

Ask Jeeves : http://www.askjeeves.com 

AOL Search : http://aolsearch.aol.com/ (internal) 

: http://search.aol.com/ (external) 

Teoma : http://www.teoma.com 

WiseNut : http://www.wisenut.com 

Inktomi : http://www.inktomi.com 

LookSmart : http://www.looksmart.com 

Open Directory : http://dmoz.org/ 

Overture : http://www.overture.com/ 

AltaVista : http://www.altavista.com 

HotBot : http://www.hotbot.com 

Netscape Search : http://search.netscape.com 

Free Software from net 

Internet is the best source to get many software called as Freeware. There are several 

sites where you can get them. The most important one is http://freedownload.com and http:/ 

/www.download.com. 

Practical Demonstrations : 

Practical demonstrations of each and every type of presentation discussed here in would 

be given to the participants during this workshop to make them well versed with the uses 

and applications of all the scientific computer tools. 


http://faculty.ncwc.edu/toconnor/425/425syl.htm 

http://latin.arizona.edu/~mgen/micgen_98/Lect24/Lect_24.htm 

http://www.arches.uga.edu/~akrueger/online.htm 

http://www.du.edu/ 

http://www.teachers-resources.com/index.html 

http://www.teachers-resources.com/teaching-topics.html#Biochemistry 

http://www.teachers-resources.com/teaching-topics.html#Biology 

http://www.ezlink.com/~edu/EBiology.htm 

http://www.infopeople.org/training/past/2001/intranet/LibraryUsesHandout.pdf 

http://dir.yahoo.com/Computers_and_Internet/Communications_and_Networking/Intranet/ 

169

Important websites related to Entomology : 

http://pest.cabweb.org/PDF/BER/Ber88-6/Ber88577.pdf. 

http://www.ars.usda.gov/research/projects/projects.htm?ACCN_NO=405094&fy=2004 

http://www.nhm.ac.uk/hosted_sites/acarology/saas/saa/pdf07/003-014.pdf 

https://www.who.int/tdr/grants/workplans/entomol.htm 

http://www.scipub.net/botany/molecular-markers-plant-genetics-biotechnology.html 

http://www.scipub.net/entomology/index.html 

http://entomology.wisc.edu/~dshoemak/Publications/Pub.htm 

http://www.intl-pag.org/5/abstracts/p-5c-159.html 


http://insects.ucr.edu/people/heraty.html 

http://www.ias.ac.in/currsci/feb252005/541.pdf 

http://www.colostate.edu/Depts/Entomology/courses/en575/en575.html 

http://www.ncbi.nlm.nih.gov/entrez 

query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10331278&dopt=Abstract 

http://www.mrcindia.org/mol-ent.htm 

170

METHODOLOGY OF PESTICIDE RESIDUE ESTIMATION 

IN VARIOUS FIELD CROPS 

Beena Kumari 



From an agricultural industry perspective, pesticides are an important component of 

economic and effective pest control and their continued use is essential. All farm chemicals 

must be utilized strategically in the farming system and only be applied with care by 

competent operators. 

Pollution of the environment poses a threat to the health and wealth of every nation. Due 

to use of pesticides in the modern agriculture, their residues become one of the major 

sources of organic pollutants. Residues of the pesticides are present in micro quantities in 

the matrix, hence involves a complicated procedure involving many steps for their analysis. 

What are Pesticides? 

Pesticides (or farm chemicals and agro chemicals) are those substances which are 

used to control, destroy, repel or attract pests in order to minimize their detrimental effects. 

Although many pesticides are injurious to humans, domestic animals, desirable plants, and 

fishes or wildlife, their usage is indispensable for protection of food plants and animals from 

death or diseases. Some pesticides are very toxic and their entry in the environment is very 

quick. Several are not highly toxic to warm- blooded beings but more or less persistent, so 

that their residues may contaminate food, animal feed and our environment for a long time. 

According to insecticide Act, 1968, under section 9(3), in India, 230 pesticides are 

registered for use till date (August, 2011). Over the years, the indiscriminate use of these 

toxic but highly beneficial compounds has given rise to many problems like resistance in 

pests, resurgence of pests and persistence of their residues, which has led to disturbance 

of agro-ecosystem. Occurrence of pesticide residues has become so wide spread that no 

component of environment is free from them. The residue level of a food or feed sample 

presents a health hazard for the consumer. This is partly because of development of highly 

sensitive analytical techniques, which can defect very low amounts of residues, which were 

earlier reported as non- detectable. The presence of residues above the permissible limit is 

also a major bottleneck in the acceptance of food commodities by importing countries in 

context to World Trade Organization (WTO) challenge. So, there is an urgent need to find 

eco friendly and efficient alternative for the control of pests. 

Pesticide Residues 

Substances, which remain in or on a feed or food commodity, soil, air or water following 

use of a pesticide. For regulatory purposes it includes the parent compound and any specified 

derivatives such as degradation and conversion products, metabolites and impurities 

considered to be of toxicological significance (F AO, 1986). 

Methodology for detection 

Pesticide residue analysis mainly comprises four steps 

1) Sampling 2) Extraction 3) Clean-up 4) Estimation 

171

Sampling : Sample should be truly representative. It should be accurate, valid, 

representative and variable. Accuracy depends on the field from where it is collected. Valid 

sample is one which, when selected ensures equal chances for each unit of the material in 

the population being sampled. A representative sample is not only a random sample but also 

that the proportion of each type of the substrate composition is identical to that of the gross 

sample from which it is selected. Larger the sample replicates, greater is the validity of the 

results but there is a limit to numbers of replicates. Residue status at different time intervals 

i.e. at harvest, post harvest and terminal stage shall differ. All the parts of plant like leaf, 

fruit, flower and seed as well as their substrates require due attention in collecting samples. 

Different samples are collected in a different manner. If quick analysis is not possible due to 

some unavoidable circumstances, samples should be stored in deep freezer (-20-40 o C). 

Extraction : The extraction techniques to be used strongly depend upon the nature of 

the matrix and of the compounds of interest. The most commonly used approach for the 

extraction of analytes from aqueous samples is liquid-liquid extraction in which the sample 

is distributed or partitioned between two immiscible solvent in which the analyte and matrix 

have different solubility or it is based on the low value of the partition coefficient for most 

organic compounds between water and organic solvents. Surface rinsing involves the keeping 

of matrix to be analysed in container, solvent addition and rotating the container for 10-15 

min. This method is very simple and relatively clean extracts are obtained. Blending involves 

the fine chopping/ grinding of substrate and blending in the presence of solvent is carried out 

for 1-2 min. This method provides better extraction due to the maximum contact of the 

substrate with solvent. Large number of co-extractives along with the analytes are extracted 

hence rigorous clean-up is needed. Soxhlet extraction is the most widely used method, 

when organic compounds have to be extracted from dry solid materials. It is particularly 

suitable when the organic material is strongly adsorbed on a porous solid matrix. The solid 

sample is placed in a filter paper thimble and kept in a cylindrical container and extracted 

with suitable non-polar solvent for 6-8 h. 

Clean-up : Clean up involves the removal of colour and unwanted impurity/ compounds 

from the extract of the analyte. Various steps/methods are involved for clean-up. 

i) Dilutions of the extract with concentrated solution of sodium chloride remove the water 

soluble impurities. 

ii) Transferring the extract to another solvent will help in removing the unwanted material 

form the analyte. 

iii) Activated charcoal help in removing the colour pigment. 

iv) Column chromatography : It involves the adsorbent and activated charcoal packed 

compactly in a glass column in an appropriate ratio in between two layers of anhydrous 

sodium sulphate and eluted with appropriate solvent mixture of solvent. Different 

adsorbents (Florisil, Silica gel, Hyflosupercel, Alumina (acidic, basic and neutral), Celite, 

Magnesia mixture) and charcoal (Non polar) are used for clean up of pesticide residues 

are polar materials. 

Estimation : Chromatographic techniques such as TLC, GLC, HPLC and HPTLC have 

been successfully used for residues estimations all over the world. Although every technique 

has its own merits and demerits. GC has been very popular for pesticide residue analysis as 

it is a dynamic method of separation and detection of micro quantities of residues, less cost 

and ability to detect wider group of pesticides. 

172

Chromatography 

It is a process of separation of constituents of a mixture of solutes through a porous 

medium by their differential movement under the influence of a moving phase. Mobile phase 

is always a gas, single or mixture of two gases. 

Basic instrument/gas chromatograph has following six main components (Fig.1 ) 

(i) Carrier Gas 

(ii) Injection port 

(iii) Oven/Column 

(iv) Detector 

(v) Recorder/Database unit. 

Carrier Gas 

Fig. 1. Schematic diagram of a gas chromatograph 

Main function of carrier gas is either to provide a flame or help in burning. Mostly hydrogen 

and oxygen is used for this purpose. The function of carrier gas is to carry vapours of analyte 

from injection port to detector through column. The carrier gas used in GC is generally 

chemically inert. Commonly used gases include nitrogen, helium, argon, and carbon dioxide. 

The choice of carrier gas is often dependant upon the type of detector which is used. Most 

commonly used carrier gas is nitrogen. However, hydrogen, helium and argon have also 

been used. 

Injection Port 

Injection port is a device to introduce the sample into the carrier gas stream and the 

substance to be analysed is injected in solution prepared in organic solvents like hexane or 

ethyl acetate. Its efficiency is reflected in the overall efficiency of the separation procedure 

and the accuracy and precision of the qualitative and quantitative results. For optimum 

column efficiency, the sample should not be too large. 

Oven/Column 

Chromatographic column is responsible for separation of component in the sample mixture 

and is called as heart of column. The shape of the column may be straight, bent or coiled. 

Columns may be made of metal (copper, aluminum and steel), glass and fused silica glass. 

The length of the column varies from 3-10 feet in case of glass and wide bore whereas it may 

vary 10-100m in case of capillary column. Efficiency of the column is inversely proportional 

to diameter of the column. 

Solid Support 

Purpose of the solid support is to provide large uniform inert surface area for the distribution 

of liquid phase. It is important to select appropriate stationary phase of columns in optimizing 

gas chromatographic separation. The stationary phase of column system is chosen after 

considering polar characteristics of the analytes, their volatility range and column temperature 

programme. Two main solid supports are Chromosorb- P and Chromosorb-W, the later being 

more inert and good for polar compounds. Chromosorb is the registered trade mark for solid 

support material for GC. 

173

Liquid Phases 

Liquid phases provide differential solubility to components of a substance, which help in 

their separation. Liquid phases are basically polymeric high melting point silicone greases. 

About 200 liquid phases are available but only six are most commonly used. Their names 

are as: SE-30 or OV-101 (dimethyl silicone), OV-17 (50% phenyl methyl silicone), carbowax 

20M (polyethylene glycol), DEGS (poly diethylene glycol succinate), Silar-10C (cyanopropyl 

silicone) and OV-210 (trifluropropyl methyl silicone).A wide range of stationary phase is 

available for WCOT capillary columns. One example is a 100 % dimethyl polysiloxane polymer 

that is chemically bonded onto the interior wall of the column and provides an example of a 

nonpolar stationary phase. 

Function of Chromatographic Column 

It helps in separation of different constituents of the substance under the influence of a 

mobile phase. 

Detectors 

Detector is the device that senses the presence of components different from the carrier 

gas and converts that information to an electrical signal. One’s choice of detector includes 

selectivity and sensitivity. Not all the detectors respond to all components. Selectivity is the 

ability of the detector to recognize and respond to the components of interest and sensitivity 

is the concentration level, detected. Sensitivity is defined as the change in the response 

with the change in detected quantity. 

Following is the list of the common detectors used for pesticide residue analysis: 

Thermal conductivity detector (TCD) 

Flame ionization detector (FID) 

Electron capture detector (ECD) 

Nitrogen phosphorus detector (NPD) 

Alkali flame ionization detector (AIFD) 

Flame photometric detector (FPD) 

Photo ionization detector (PID) 

Mass selective detector (MSD 

Multiresidue Methods for Estimation of Pesticide Residues 

Estimation technique for single pesticide only can not be followed for detection of residues 

of all categories of pesticides. Hence, this constantly expanding use of pesticides on food 

crops accentuates the need for rapid, precise and sensitive method for determination of 

pesticide residues of all the major groups of pesticides. In such situation, multi-residue 

analytical technique can be efficiently followed for detection and estimation of multiresidues 

of intra and inter class xenobiotics . 

The purpose of multiresidue analyses is to determine the residues of as many pesticides 

as possible within a short period of time even if the recoveries of some compounds are low. 

In multiresidue methods the recoveries up to 70% are accepted. The recoveries less than 

70% have to be mentioned specifically. 

Complete methodology for the estimation of pesticide residues in different commodities 

are given. 

174

1. Estimation of Pesticide Residues in Vegetables and Fruits (Kumari et al., 2001, 2006) 

Flow diagram of extraction of multiresidues from vegetable and fruits is shown below : 

Extraction 

Take bulk sample (1-2 kg) of vegetable/fruit 

Chop it into small pieces and mix properly 

After quartering take 20g representative sample 

Macerate it with 4-5g anhydrous sodium sulphate 

Add 100 ml acetone and extract by shaking on mechanical shaker for 1 hour 

Filter the extract through 2-3 cm layer of anhydrous sodium sulphate 

Concentrate the extract to 40 ml on rotary flash evaporator after adding a drop of mineral 

oil 

Dilute the extract 4-5 times with 10% NaCl aqueous solution 

Partition it thrice with ethyl acetate (50, 30, 30 ml) in a separatory funnel by shaking 

vigorously for one minute 

Combine the organic (ethyl acetate) phases and filter through anhydrous sodium sulphate 

Concentrate the organic phase up to 5 ml on rotary vacuum evaporator 

Divide the concentrated extract into two equal parts (one for organochlorines and 

synthetic pyrethroids and other for organophosphates and carbamates) 

Clean-up 

For Organochlorines and Synthetic Pyrethroids 

Pack the glass column (60 cm x 22 mm i.d) with adsorbent mixture (5g) Florisil : 

activated charcoal (5:1 w/w) in between two layers of anhydrous sodium sulphate 

Tap the column gently to ensure uniform and compact packing 

Prewett the column with 50 ml hexane and transfer the concentrated extract to the 

column 

Elute the column with 125 ml solution of ethyl acetate: hexane (3:7 v/v) 

Concentrate the eluate to near dryness using rotary vacuum evaporator followed by gas 

manifold evaporator after adding one drop of mineral oil 

Make the final volume to 2 ml in ethyl acetate: n-hexane (3:7 v/v) 

175

For Organophosphates and Carbamates 

Pack the glass column (60 x 22 mm i.d.) with adsorbent mixture containing 5g silica gel (60-120 

mesh): activated charcoal (5:1 w/w) in between 3-4 cm layers of anhydrous sodium sulphate 

Ensure the compact packing of the column by taping gently 

Prewett the column with 50-60 ml hexane and load the concentrated extract to the 

column 

Elute the column with 125 ml mixture of acetone: hexane (3:7 v/v) 

Concentrate to near dryness using rotary flash evaporator followed by gas manifold 

evaporator 

Make the final volume to 2 ml in acetone: n-hexane (3:7 v/v) 

2. Estimation of Pesticide Residues in Feed and Fodder (Kumari et al., 2006) 

Extraction 

(i) Take 10g representative sample from coarsely powdered bulk sample. 

(ii) Add 200 ml of 1% aqueous acetonitrile. 

(iii) Extract it for 8 hours on Soxhlet extraction apparatus. 

(iv) Transfer the extract to 1L separatory funnel and dilute 4-5 times with 10% NaCl solution. 

Liquid-Liquid Partitioning 

(i) Partition the extract twice with hexane (2 x 100 ml followed by partitioning twice with 

dichloromethane (2 x 100 ml) by vigrous shaking for 1 min. each time. 

(ii) Combine the both organic phases i.e. of hexane and dichloromethane. 

(iii) Add a drop of mineral oil and concentrate to 10 ml on rotary flash evaporator. 

Clean up 

(i) Pack the glass column (60 cm x 20 mm i.d.) compactly with adsorbent mixture 15g 

silica gel (60-120 mesh, prewashed and activated at 1200C for 1h), 0.5g activated 

charcoal and 5g Florisil in between 2-3 cm layers of anhydrous sodium sulphate. 

(ii) Prewet the column with 50-60 ml hexane. 

(iii) Load the concentrated extract on column and elute with 150 ml mixture of acetone : 

dichloromethane (1:1 v/v) at a flow rate of 4 ml/min. 

(iv) Divide the eluate into two equal portions; one for OC, SP and other for OP and carbamates. 

(v) Evaporate first portion to near dryness first on rotary flash evaporator followed by gas 

manifold evaporator. 

(vi) Dissolve the residues in hexane and again concentrate up to dryness. 

(vii) Repeat the process three times more to remove traces of dichloromethane. 

(viii) Make the final volume to 2 ml in n-hexane for the estimation of organochlorine and 

synthetic pyrethroid insecticides. 

(ix) Evaporate the second portion to near dryness on rotary flash evaporator/gas manifold 

evaporator. 

(x) Make the final volume to 2 ml in ethyl acetate for the estimation of organophosphate 

and carbamate insecticides 

176

3. Estimation of Multiresidues in Food Grains 

QuEChERS’s Method 

It is a relatively new Multi-residue method (QuEChERS) for determining pesticide residues 

in different matrices. The Change in pesticide usage pattern over the past some years has 

necessitated to develop residue analytical techniques capable of qualitative detection and 

quantitative estimation of the multiresidues resulting from application of different xenobiotics 

of intra and inter class chemicals on field crops. In 2003 the QuEChERS method for pesticide 

residue analysis was introduced which provides high quality results in a fast, easy and 

inexpensive approach. Follow up studies have further validated the method for >200 pesticides, 

improved results for the remaining few problematic analytes and tested it in fat containing 

matrices. This method has been explined in detail by Lehotay (1994). 

Principle of the QuEChERS Method 

The QuEChERS method known as the quick, easy, cheap, effective, rugged and safe for 

pesticide residues involves the extraction of the sample with acetonitrile (MeCN) containing 

1% acetic acid (HAc) and simultaneous liquid-liquid partitioning formed by adding anhydrous 

177

magnesium sulphate (MgSO ) plus sodium acetate (NaAc) followed by a simple cleanup 

4 

step known as dispersive solid-phase extraction (SPE). The method is carried out by shaking 

a Teflon centrifuge tube which contains 1 ml of 1% of HAc in MeCN plus 0.4 g anh. MgSO4 and 0.1 g anh. NaAc per g sample. The tube is then centrifuged and portion of the extract is 

transferred to a tube containing 50 mg primary secondary amine (PSA) sorbent to remove 

fatty acids among other components plus 150 mg anh. MgSO per ml extract to reduce the 

4 

remaining water in the extract. (the dispersive-SPE cleanup step). Then, the extract is 

centrifuged and transferred to autosampler vials for concurrent analysis by gas 

chromatography/mass spectrometery (GC/MS) and liquid chromatography/tandem mass 

spectrometry (LC/MS-MS). 

Advantages of QuEChERS method over the traditional multiresidue methods 

The QuEChERS method has several advantages over most traditional methods of analysis 

in different ways: (i)high recoveries (>85%) can be achieved for a wide polarity and volatility 

range of pesticides, including notoriously difficult analytes, (ii)very accurate results are 

achieved because an internal standard (I.S.) is used to correct for commodity to commodity 

water content differences and volume fluctuations,(iii) high sample throughput of about 10- 

20 pre-weighed samples in about 30-40 min is possible, (iv) solvent usage and waste is very 

small and no chlorinated solvents are used, (v) a single person can perform the method 

without much training or technical skill, (vi) very little glassware is used , (vi) method is 

quite rugged because extract cleanup is done to remove organic acids, (vii) very little bench 

space is needed, thus the method can be done in a small laboratory if needed, (viii) the 

MeCN is added by dispenser to an unbreakable vessel that is immediately sealed, thus 

solvent exposure to the worker is minimal, (ix)the reagent costs in the method are very 

inexpensive and (x) few devices are needed to carry out sample preparation. 


Agnihotri, N.P.,1980. Gas chromatography In: Residue Analysis of Insecticide (ed. Gupta, 

D.S.), Department of Entomology, HAU, Hisar : 130-140. 

Dean, J.R., 1998. Extraction Methods for Environmental Analysis. John Willey & Sons. Ltd. 

West Sussex, England. 

Kumari, Beena and Kathpal, T.S., 2010. Pesticides and Methods for Their Residue Estimation. 

New India Publishing Agency, 101,Vikas Surya Plaza,LSC Market, CU, A0 Block, Pitam 

Pura, New Delhi-110 088, xii+226 p, ISBN:978-93-80235-39-4. 

Kumari, Beena, Madan, V.K. and Kathpal T. S., 2006. Monitoring of pesticide residues in 

fruits. Environ. Monit. and Assess. 123 : 407-412. 

Lehotay, S.J.,2004. Quick, easy, cheap, effective, rugged and safe (QuEChERS) Approach 

for determining pesticide residues. In : Pesticide Analysis in Methods in Biotechnology( 

eds. Vidal Martinez, J.L. and Garrido Frenich,A.), Humana Press, USA 

Nakamura, Y., Tonogaiy, Sekiguchi, Y., Tsumura, Y., Nishida, N., Takakura, K., Isechi, M., 

Yuasa, K., Nakamura, M., Kifune, N., Yamamoto, K., Terasewa, S., Oshima, T., Miyata, 

M., Kamakura,K. and Ito, Y.: 1994, ‘Multi-residue analysis of 48 pesticides in agricultural 

products by capillary gas chromatography’, J. Agric. Fd. Chem. 42 : 2508–2518. 

Ravinderanath, B., 1989. Principles and Practice of Chromatography. Pub. Ellis Horward 

Ltd. Chickester, England. 

Sharma, K. K., 2007.Pesticide Residue Analysis Method. Directorate of Information and 

Publications of Agriculture, New Delhi Kumari, Beena, Kumar, R. and Kathpal, T.S., 

2001.An improved multiresidue procedure for determination of 30 pesticides in vegetables. 

Pestic. Res. J. 13 (1) : 32-35. 

178

DIAGNOSTICS AND LOSS ASSESSMENT DUE 

TO INSECT-PESTS IN SUGARCANE 

Saroj Jaipal 

CCS Haryana Agricultural University, Regional Research Station, 

Uchani, Karnal -132001 (Haryana), India 

Sugarcane crop is exposed to several depredatories during the course of its germination, 

growth and maturity. Among these, insects are one of the important scourges. More than 

200 species of insects have been reported on the crop in the country, out of which about two 

dozen species are considered of economic importance.These are tissue borers (shoot borer, 

root borer, green borer, Gurdaspur borer, top borer, stalk borer, internode borer, Plassey 

borer, pink borer ), sap suckers (pyrilla, scale insect, black bug, mealybug, whitefly, aphid), 

subterranean insects (termites, white grubs) and defoliators (grasshoppers, armyworm, 

weevils). Some of these pests have assumed considerable significance in subtropics where, 

because of availability of conducive environment for their build up, the field and factory 

losses are substantially high. 

In India, since sugarcane is grown under very diverse agro-climatic conditions, the crop’s 

pest complex is also evidently dissimilar in respect of their ecology. The two markedly 

distinct agro-ecological zones- the tropical peninsular zone with moderate climate and the 

subtropical with extremes of weather conditions have their own set of pest fauna. In subtropics, 

the main insects injurious to cane are – the shoot borer (Chilo infucatellus Snellen), top 

borer (Scirpophaga excerptalis Wlk.), stalk borer (C. auricilius Dudgn.), Gurdaspur borer ( 

Acigona steniellus Hmpsn), leaf hopper (Pyrilla perpusilla Wlk.), black bug (Cavelerius sweeti 

Slater and Mugomoto ), termites, Odontotermes obesus Rambur and Microtermes obesi 

Holmgren). A few insects like root borer ( Polyocha depressella Swinhoe) and whitefly 

(Aleurolobus barodensis Mask.) which hitherto were minor problems in the crop now have 

assumed considerable significance due to changing climatic conditions. The recent problems 

in the region include grasshoppers (Hieroglyphus banian F.) white woolly aphid (Ceratovacuna 

lanigera Zehnt.) in Western Uttar Pradesh, slug caterpillar ( Prasa bicolour Wlk.) and white 

grub (Heteronychus sp.) in Haryana and Western Uttar Pradesh. The problems in tropic are 

fewer than the subtropics. Here, the key pests are early shoot borer (C. infuscatellus), 

internode borer (C. sacchariphagus indicus Kapur), white grubs (Holotrichia serrata, 

Leucuopholis lepidophora, Heteronychus robustus, H. annulatus), scale insect, Aulacaspis 

tangalensis), mealy bug (Saccharicoccus sacchari Cockrell).The white woolly aphid which 

earlier was restricted to Nagaland and Assam as a minor pest has recently reached epidemic 

proportions in Maharashtra and Karnataka. The geographical distribution of cane insect pests 

as per their current status in various sugarcane growing states of India is listed in Table 1. 

Sugarcane shoots or stalks, right from top to the root are liable to damage by different 

pests resulting in the chewing or gnawing of the plant tissues or sucking of plant sap. 

Monoculture and contiguity of the crops for years in the field (multiple ratoons) provide 

conditions ideal for establishment, multiplication and spread of the pests. Ravages due to 

the pests therefore, are far more severe and diverse in sugarcane than in any short duration 

crop. 

Moth borers are the key pests of sugarcane crop in subtropics. On the basis of symptoms 

of damage, these are conveniently grouped as stem and top and shoot borers. The stem 

borers, namely, stalk borer (Chilo auricilius Ddgn.) and Gurdaspur borer (Acigona steniellus 

Hampson) are very destructive in north-eastern parts, while top borer (Scirpophaga excerptalis 

179

Table 1. Status of major sugarcane insect-pests in India 

Insect pest / Species Pest status Distribution 

Borers 

Root borer, Polyocha Major Punjab, Haryana, Bihar, Madhya Pradesh, UP, 

(Emalocera) depresella Gujarat, Maharashtra, Karnataka, Andhra, TN 

Swinhoe Minor Assam, Orissa 

Early shoot borer, Chilo Major All sugarcane areas 

infuscatellus Snellen 

Top borer, Scirpophaga Major Punjab, Haryana, UP, WB, Assam, MP, Gujrat, 

excerptalis Walker Maharashtra 

Minor TN, Karnataka, AP, Kerala 

Stalk /stem/tarai borer, Major Haryana, Punjab, Uttar Pradesh, Bihar 

C. auricilius Dudgeon Minor Nagaland, HP, WB, Orissa 

Internode borer, Major Tamil Nadu, Kerala, Karnataka, Andhra Pradesh, 

Maharashtra, Uttar Pradesh, 

C. sacchariphagus indicus Kapur Minor Bihar, West Bengal 

Gurdaspur borer, Major Punjab, Haryana West Uttar Pradesh 

Acigona steniellus Hampson Minor Rajasthan, Himachal Pradesh, Maharashtra 

Pink borer, Sesamia Major UP, Bihar, Rajasthan, Maharashtra, Karnataka 

inferens Walker Minor Remaining sugarcane states 

Plassey borer, Major Assam, West Bengal, Bihar 

C. tumidicostalis Hmpson Minor Nagaland, Orissa 

Green borer, Minor Northern India 

Rhaphimetopus ablutella Zell 

Sucking pests 

Black bug, Cavelerius sweeti Major Haryana, Punjab, Uttar Pradesh, West Bengal 

Slater and Mugomoto Minor Bihar, MP, Rajasthan, HP. Assam 

Black bug, Major Maharashtra, Uttar Pradesh 

Dimorphopterus gibbus F. Minor Punjab, Bihar, Rajasthan, MP 

Thrips, Baliothrips Minor Haryana, Punjab, Uttar Pradesh, Bihar 

serratus Kobus 

Thrips, Stenchaetothrips Sporadic Haryana, Panjab, Uttar Pradesh 

indicus Ramk. And Marg. 

Thrips, Hoplothrips Minor Haryana, Panjab, Uttar Pradesh 

tolerabilis Priesner 

Whitefly, Aleurolobus. Major Haryana, Punjab, Uttar Pradesh, Bihar, Gujrat 

barodensis Mask Minor Karnataka, Tamil Nadu, Andhra Pradesh 

Whitefly, Neomuskellia Major Bihar, TN, Karnataka, Maharashtra, MP 

bergii Sign Minor Haryana, Punjab, UP 

180

Scale insect, Melanaspis Minor Tamil Nadu, Haryana (in pockets), Maharashtra, 

glomerata Green Scale insect, MP, Gujrat, Andhra, Karnataka, Bihar, 

Aulacaspis maudinensis Zehntner West Bengal and Assam 

Mealy bug, Saccharicocus Minor All sugarcane areas 

sacchari Cockerell 

Mealy bug, Kiritschenkella Sporadic 

sacchari Green 

Leaf hopper, Pyrilla Major All sugarcane areas 

perpusilla Walker 

White wooly aphid, Major Maharashtra, Karnataka 

Ceratovacuna lanigera Zehnit Minor Western UP, Uttranchal 

Subterranean pests 

Termite, Microtermes Major Haryana, Punjab, TN, AP, Karnataka, UP 

obesi Holmgren Minor MP 

Termite, Odontotermes Major All sugarcane areas 

obesus Rambur 

White grub, Holotrichia. Major Haryana, Panjab, UP, AP, Maharashtra, TN, 

consangyinea Blanch. H. Karnataka, Rajasthan, Bihar 

serrata Fabr. Blanch 

Mealy bug, K. sacchari Green Sporadic 

Defoliators 

Grass hopper, Heiroglyphus Minor All sugarcane areas 

banian F. 

Grass hopper, Poekilecerus Sporadic All sugarcane areas 

heiroglyphicus Klug. 

Army worm, Mythimna separata W. Sporadic All sugarcane areas 

walker) and shoot borer (Chilo infucscatellus Snellen) are of wide occurrence. The root borer 

(Polyocha depressella Swinhoe) has also assumed serious proportions since 1984. There 

are two aspects to tissue borers’ problem according to the stage of crop growth. At formative 

phase, very young shoots whether virgin or ratoon are subject to attack by most species, 

almost in conjunction. Irrespective of the species involved, the larvae destroy the apical 

meristem resulting into death of shoots. The leaf spindles first turn brown to die and 

subsequently develop into characteristic ‘dead hearts’. This does not necessarily affect 

crop yield because more tillers emerge which under normal physiological conditions are 

able to compensate to a considerable extent for early loss of shoots. However, heavy loss of 

shoots in young crop may occur in fields due to physiological stresses or shortening of 

tillering phase. Beyond formative phase, when stems have already formed, significant losses 

are caused by the larvae as they eat their way along the spindles and stems cutting holes 

and galleries, impairing growth, destroying meristematic, transport and storage tissues, 

causing breakage of canes and thereby reducing both cane yield and quality. Also wound 

181

injury caused by the borers offers an opportunity for the entry of microorganisms into the 

plant tissues. Microbes not only deteriorate juice quality but also augment losses. 

Black bug, Cavelerius sweeti and leaf hopper, Pyrilla perpusilla are the main sap sucking 

pests of sugarcane. The nymphs and adults of black bug hide in the central leaf whorl, under 

the sheathing basis of leaves and in crop residue continuously feeding on the leaves which 

in turn become pale yellow with brown rust irregular spots. Severe infestation causes drastic 

reduction in crop growth. Pyrilla has been reported to occur sporadically in a severe form at 

intervals of 5-8 years. The infested leaves besides turning pale yellow and then brown to dry 

also develop sooty mould leading to arrest of photosynthetic activity and hence of sugar and 

yield. Scale insect juveniles desap the parenchymatous cells reducing their size and content. 

The severely infested canes show pithiness and are found to contain less juice. Aphids, 

whiteflies and mealy bugs also attack sporadically the cane crop, the former occurring 

particularly under unusual weather conditions. 

These pests have been reported to inflict varying degree of losses in yield and sugar 

depending chiefly on factors like the variety under cultivation, stage of crop attacked and the 

environmental conditions. Generally speaking, the losses are in terms of reduced cane tonnage 

and reduced available cane sugar per unit weight of millable canes. Further, monetary loss 

due to higher cost of processing particularly of canes damaged by scale insect, mealy bug, 

termites, grubs, rats and borers in the factory has also been observed. The effects of pest 

damage on recoverable sugar contents of the cane have been quoted quite often. However, 

the actual assessment of damages and losses has not been feasible mainly because of 

errors arising from different sampling as well as milling techniques. Moreover, the available 

figures generally pertain to losses due to individual pests, a situation quite arbitrary to 

natural conditions where multiple infestations are of common occurrence. A brief resume of 

losses in cane yield and sugar recovery over different periods is as under :- 

A positive correlation between shoot borer incidence and intensity and a negative one 

between incidence and yield as well as intensity and yield have been established (Avasthy, 

1968). In top borer infestation, as the crop grows, the mortality of shoots/canes decreases 

(Agarwal and Siddiqi, 1964). No correlation has been observed between borer infestation 

and the actual damage (Rajani, 1960; Siddiqi, 1960). In Punjab 20 (Kalra, 1960a, b) to 30 

per cent (Rajani, 1960) loss has been reported. The yield loss is highest due to the third 

brood (Kalra and Chaudhary, 1964a). Top borer infestation induces early maturity in crops 

more than 9 months old and improves quality (David and Ranganathan, 1960; Kalra and 

Chaudhary, 1964a) which however shows marked deterioration subsequently. The loss in 

quality is highest due to the third brood. The loss in sugar recovery varies from 0.2-4.1 units 

(Rajani, 1960; Siddiqi, 1960; Venkataraman, 1961; Gupta et al.,1965). Agarwal (1964b) 

observed the damage in a cane due to internode borer can go up to 22.5 cm. He reported 

10.7 per cent loss in weight based on the study in 30 varieties. The reduction in sucrose 

content is variable depending on the variety, age of the crop and intensity of attack (David 

and Ranganathan, 1960; Agarwal, 1964b). A maximum reduction of 1.12 per cent in recovery 

in Co 449 has been reported when planting was done during special season (David and 

Ananthanarayana, 1963). Significant correlations have been reported between borer incidence 

and intensity, larval population and intensity and incidence, intensity and loss in cane yield 

(Avasthy and Krishnamurthy, 1968). Gurdaspur borer damages usually 15-20 per cent of the 

crop which sometimes may be even as high as 40-50 per cent (Kalra, 1963 a,b). Gupta et al. 

(1966) worked out the loss caused by second, third and fourth brood of root borer. Teotia et 

al. (1963) reported 30-60 per cent destruction of buds due to termite attack, while Avasthy 

(1967b) reported it to be 40 per cent which results in a yield loss of 33 per cent. 

182

Table 2. A profile of losses in cane sugar and recovery 

Pests Losses in cane sugar and recovery Source 

Shoot borer 0.6 tonnes sugar per hectare0.35 tonnes in Khan & Krishnamurthy (1956) 

sugar/ 5% incidence and0.25 tonnes in sugar/ Avasthy(1968) 

1% intensity 

Top borer 0.2 to 4.1 units in sugar recovery7q/ha under Chaudhary (1983) 

heavy attack21.5%(third brood),12% ( fourth Kalra & Chaudhary (1964) 

brood) , 8 % (fifth brood) as of healthy Kalra (1991), Jaipal (1992) 

Stalk borer 1.7 to 3.7 units at 29% infestation 1.95 units Gupta and Singh (1971) 

sugar recovery 5.3 to 20% in sucrose 0.64% Kulshreshtha & Avasthy (1957) 

in juice extraction and 0.56%or 0.08 unit/1.0% Singh et al. (1973) 

intensity0.07% in brix and 0.1 unit in pol% at Bhardwaj et al. (1980) 

every unit increase in intensity Varma(1984) 

Gurdaspur borer 29% in sucrose with an increase of 84% in Singh et al.(1957) 

glucoseUpto74%in sugar recovery Garg and Chaudhary (1979) 

Root borer 0.3 unit loss of sucrose in U.P.and 2.9% in Gupta and Chaudhary (1970) 

Bihar7.9%in CCS over healthy and 78.7% Jaipal (unpublished) 

in CCS in wilted canes 

Pyrilla 2 to34% in sucrose, 0.2 to 5 units in recovery Gupta(1948) 

and 2.2 to 4.4 % in jaggery 10-31% in ratoon, Jaipal et al . (1993) 

24-60% in autumn , upto15% in plant at high 

infestation level 

White fly 30-40% in sucrose and 20-25% in total solid, Singh et al.(1956) 

1.98% in juice sucrose of plant crop,1.44, 1.66, Siddiqi and Sexana (1960) 

and 2.69% in manured and 2.52, 2.46,and 3.33% 

in unmanured first, second and third ratoon crop 

1.21, 2.71 and 2.81 units in recovery in light , 

medium and heavily infested 

Black bug 2-56% reduction in growth Jaipal (1991) 

Scale insect 0.3- 42 % in juice extraction 44% in sucrose and Moholkar et al. (1976) 

35% in CCS poor quality jaggery with 6% losses Prabhakar Rao et al. (1976) 

42-58% (highly infested),18-29% (moderate Jaipal (1986) 

infestation), upto 9% in lightly infested 

Mealy bug 24%in sucrose and 16% in brix Kalra and Sidhu(1964) 

Rats 23 kg /ha in recovery0.68 unit in sugar recovery Gupta et al. (1968) 

Bindra and Sagar (1968) 

Termite 4.5% in sugar, 5-13 kg of sugar/q Agarwala (1955) 

Gupta and Singh (1971) 

Grasshopper 0.4-1.2 units in sugar recovery Jaipal (1997) 

183

Due to scale insect infestation shriveling of cane and stunting of growth is reported by 

Agarwal (1960), Raja Rao and Bhaskar Rao (1960) and Tembhekar (1965). Tembhekar (1965) 

observed yellowish streaks on leaves due to the feeding of nymphs. Use of infested setts 

for planting hampers germination upto 20 per cent (Agarwal, 1960). Reduction in cane 

weight, which is directly related to degree of infestation, is 13 per cent in Co 740 in Tamil 

Nadu (Agarwal, 1960), 63.4 in Co775 at Bardoli in Gujarat (Tembhekar, 1965), 6-15.2 at 

Walchandnagar in Maharashtra (Deshpande 1969), 2.9 in Co 740 in adsali crop and 3-14 in 

pre – seasonal planted crop (Phadke et al., 1969). The reduction in sucrose, brix and purity 

is reported to be 42, 28 and 26 per cent respectively (Agarwal, 1960). In Co 775, the purity 

of juice declines from 89.8 to 61.4 per cent (Tembhekar, 1965). The loss is more in special 

season crop than in main season crop (Raja Rao and Bhaskar Rao, 1960). Studies by Kalra 

and Sidhu (1964) have shown that in canes severely infested by mealy bugs, the sucrose 

content decreases by 24.1 per cent, while the reduction in brix is 16.2 per cent. 

Pyrilla infestation causes serious losses in north India. During 1968-69 epidemic, the 

reduction in recovery was noted to the extent of 50 per cent. In some factories in western 

Uttar Pradesh, the sugar recovery was even below 5 per cent (Agarwal, 1969a). Gupta and 

Gupta (1969) estimated the total loss in sugar production to be 60,000 tonnes, equivalent to 

a monetary loss of ten crores in eastern Uttar Pradesh alone. According to Saxena (1969) 

the canes affected by Pyrilla pose several problems for milling. 

In Uttar Pradesh, Gupta et al. (1968b) estimated the loss in yield due to rats to be 532 

kg/ha and loss in sugar recovery to be 3 kg/ha. Bindra and Prem Sagar (1968) found that in 

Punjab, rat damage is highly variable across locations, ranging from nil/negligible to heavy 

damage. 

Studies carried out at Anakapalle (Subha Rao, 1972) showed that when the incidence of 

dead hearts by shoot borer did not exceed 22 per cent, the varieties were able to overcome 

the infestation resulting in no apparent reduction in the number of shoots or weight of clumps 

at harvest provided the mother shoots were healthy. The study of Seshagiri Rao and 

Krishnamurthy (1973) has revealed the economic threshold level of shoot borer to be 15 per 

cent. The variation in yield loss due to top borer attack is attributed to variety and stage of 

the crop attacked (Agarwal et al., 1974). The yield loss is highest due to the third brood 

(Kalra and Prasad, 1978). In the case of internode borer attack, 85 per cent fresh attack is 

found in the top five immature internodes. The number of internodes bored per cane has 

been observed to vary from 1.6 in Co 453 to 4.0 in Co 6304 (David, 1979). In three factory 

areas in Tamil Nadu, viz. Sakthi Nagar, Nellikuppam and Pettavaithalai, the actual loss 

amounted to 19.0, 16.3 and 8.6 tonnes/ha respectively, when mean per cent canes damaged 

was 40.0, 42.4 and 55.4 respectively (David et al., 1979). 

In stalk borer, Singh et al., (1973) observed a direct correlation between incidence and 

loss in yield. They also observed 31.8 per cent loss in yield and 5.3 – 20.4 per cent in 

sucrose. A positive correlation was observed between intensity of infestation and per cent 

loss in yield, juice extraction and sugar recovery (Bhardwaj et al., 1980). Loss in sugar 

recovery due to Gurdaspur borer infestation may be as high as 74 per cent in areas severely 

infested by the borer (Garg and Chaudhary 1979b). In Karnataka, the yield loss due to 

whitegrubs (H.serrata) is as high as 100 per cent (Veeresh, 1974) in some heavily infested 

fields. 

Planting setts infested with scale insect reduced germination by 11.3 per cent in Co 740 

to 21.4 per cent in Co 419 (Thontadarya and Govindan, 1976). The reduction in cane height 

184

varied from 5.5 per cent in Co 419 (Sathiamoorthy and Muthukrishnan, 1978) to 29.0 per 

cent (Moholkar et al., 1973). The reduction in girth of canes ranges from 2.8 – 12.1 per cent 

(Sithanantham et al., 1974b) and it may go as high as 19.1 per cent (Sathiamoorthy and 

Muthukrishnan, 1978). The loss in cane yield varied from 2 to 54.6 per cent in different 

varieties in different states (Moholkar and Ranadive, 1973; Sithanantham et al.,1974b; 

Seshagiri Rao, 1975, Bhaskara Rao et al., 1976; Sathiamoorthy and Muthukrishnan, 1978). 

A loss in yield to the tune of 25 – 30 tonnes/ha at Shakarnagar, Andhra Pradesh, amounted 

to a monetary loss of Rs.4500 – 5400 (Srinivasamurthy and Subba Rao, 1976). The degree 

of losses also seems to be influenced by soil type Thontadarya and Govindan, 1976), seasons 

of planting (Moholkar et al.,1976) and varieties (Sithanantham et al.,1974a; Moholkar et 

al.,1976). The constant desapping of canes results in the reduction of juice content from 

0.3 per cent (Moholkar et al., 1976) to as high as 41.4 per cent (Prabhakara Rao et al., 

1976). In Tamil Nadu, 5.9 to 7.2 per cent reduction in sucrose and 8.5 to 15.0 per cent 

reduction in CCS in varieties Co 419 and Co 458 are reported (Sithanantham et al.,1974b). 

According to Seshagiri Rao (1975) the loss in sucrose, purity and brix in Co 997 is 44.9, 

16.7 and 33.0 per cent while Bhaskara Rao et al. (1976) estimate it to be 5.7, 6.6 and 5.1 

units respectively in Co 527 in Andhra Pradesh. In Uttar Pradesh the sugar recovery is 

reduced by 1.7, 2.3, 3.3 and 9.1 units under varying levels of scale insect infestation (Shukla 

and Trupathi, 1980). The syrup prepared from the juice of scale insect infested canes does 

not set properly (Prabhakara Rao et al.,1976). According to Moholkar and Ranadive (1973) 

there is reduction in gur production and the jaggery produced is dark in colour with high 

reducing sugars. 

By postal survey, Hopf et al. (1976) obtained yield loss estimates due to rats. It was 

2.2 per cent in Punjab, 2 to 5 per cent in Karnataka and ‘light loss’ in Tamil Nadu, Srivastava 

(1975) reported 16.7 per cent loss due to rodents. Studies on qualitative and quantitative 

losses caused by the top borer, S.excerptalis has shown that the third brood of the pest in 

autumn season caused maximum loss (Gupta et al., 1993; Duhra and Sharma, 1993). Pink 

mealy bug S.sacchari decreased the sucrose and sugar content of the cane and its purity 

without affecting the volume of the cane juice significantly (Aliqui and Murad, 1992). 

Singla and Duhra (1991) proposed a sampling a plan for estimating damage by 

E. depressella (40 shoots), C. infuscatellus (30-40 shoots), S. excerptalis (40 canes) and 

C. auricilius (30 – 40 canes). Upadhyay and Vaidya (1993) estimated 36.5 to 42.9 per cent 

infestation due to M. glomerata causing 16.6 to 20.6 per cent loss in cane weight. Root 

borer, E.depressella followed a negative binomial distribution (Sardana, 1994) under field 

conditions. Depending upon the degree of infestation by pyrilla which is influenced by the 

prevailing climatic conditions (Varma and Tanwar, 1993), varieties suffered varying level of 

losses in sugar recovery (Jaipal et al.,1993). 


David, H.; Easwaramoorthy, S. and Jayanthi, R. (eds.). Sugarcane Entomology In India. 

Sugarcane Breeding Institute, (Indian Council of Agricultural Research), Coimbatore 

641 007, 1986. 

Singh, S. B.; Rao, G. P. and Easwaramoorthy, S. (eds.). Sugarcane Crop Management. Sci 

Tech Publishing Llc. 9207, Country Creek Drive, Houston, Texas-77036 (USA). 

185


DUE TO INSECT-PESTS IN CEREAL CROPS 

Ombir 


CCS Haryana Agricultural University, Hisar-125 004 

Till recently, wheat in India was considered relatively free from ravages of insect pests in 

field, except termite damage under rainfed conditions. However, the changes that have 

occurred in wheat production system over the past three decades and adoption of intensive 

system have markedly altered the situation. The changes in the crop field environment have 

been conducive for development and multiplication of certain insect species which are cause 

damage to wheat crop. 

Shoot fly, Atherigona naqvii 

Shoot fly has emerged as an important and regular pest of late sown wheat crop since 

the adoption of semi-dwarf varieties. The fly is about 3 mm in body length and dark gray in 

colour. Its prevalence has been reported from Rajasthan, Gujarat, Madhya Pradesh, Uttar 

Pradesh, Panjab and Haryana. Infestation can occur during all crop growth stages but damage 

to young seedling and tillers is most important. The newly hatched maggots creep into the 

leaf sheaths of the tillers and cut the central growing shoots causing dead hearts. In case of 

severe infestation, the plant assumes bushy appearance with large number of tillers. 

Wheat aphid, Sitobion avenae 

Wheat aphid attacks wheat, barley, oats, etc., and is widely distributed in India. The 

aphid is a soft-bodied, lime-green colour insect with a darker green stripe on its back. It 

sucks sap from the ears and tender leaves, causing decrease in yield of the crop. The 

damage is particularly severe in years of cloudy weather. Yield losses are high when 

infestation occurs at booting to milky dough stage, particularly where aphids are colonising 

the flag leaf, stem and ear. Heavy infestations can cause a reduction of the number of grains 

per ear; generally, the distal grains in the head fail to fill and thus a noticeable reduction of 

the yield. Infestations at milky dough stage in which aphids colonise on leaves, particularly 

lower in the canopy, tend to result in grain with reduced protein rather than a loss in yield. 

Aphids intercept the nitrogen being relocated from leaves to the filling grain. 

Ghujia weevil, Tanymecus indicus 

Weevils are earthen grey in colure and cannot fly. 

The adults feed on leaves and tender shoots of the plants. The damage is caused by the 

adult weevils only and they cut the germinating seedling at ground levels and often crop has 

to be resown. 

Stem borer, Sesamia inferens 

Stem borer are lay eggs in clusters inside the leaf-sheaths. The larvae of stem borer 

feed on leaf sheath for about a week and then bore inside the stem causing dead-hearts at 

the vegetative and reproductive phases and white ears at ripening, which could be easily 

pulled out. 

186

Cutworms, Agrotis spp. 

Cutworms are soil inhabiting pests of mainly young plants. Larvae usually feed at night 

and seek refuge in the soil by day. They normally attack seedling plants by cutting through 

their stems near ground level but they may also feed on the foliage of older plants. Most 

damage is done between germination and tillering. Damage usually shows up as general 

patchiness or as distinct bare areas in a very short time. In severe infestation, whole field is 

covered with cut plant necessitating resowing. The larvae mature in about four weeks but in 

cooler conditions this may be much longer. 

Armyworm, Mythimna separata 

The armyworm typically becomes a pest of wheat at ears. It prefers “green” tissue, and 

ordinarily feeds first on the tender leaves, then on the awns and immature grains. 

The freshly emerged larvae spin threads from which they suspend themselves in the air 

and then with the help of air currents reach from one plant to another. In the early stages, 

they feed on tender leaves in the central whorl of the plant. The larvae are found in the 

cracks of soil and hide during the day but feed during night or early morning. In the case of 

a severe attack by the armyworms, whole leaves, including the mid-rib, are consumed and 

field looks as if grazed by cattle. The pest may also eat away ears, including the awns and 

immature grains. The most obvious damage to wheat is “head clipping,” when caterpillars 

chew completely through the stem and the head falls off the plant. During the vegetative 

growth phase, plants can tolerate considerable leaf feeding. Leaves may look tattered from 

the eaten-out leaf margins. Faecal pellets around the base of plants are another indication 

of armyworm infestation. The most serious armyworm damage in cereal crops occurs when 

larvae feed on the upper flag leaf and stem node as the crop matures. Larvae target the stem 

node as the leaves become dry and unpalatable, and the stem is often the last part of the 

plant to dry. Head cutting begins at this time. 

Surface grasshopper, Chrotogonus trachypterus 

Adults are about 20 mm long, flattened the upper surface of a dark earthen colour, 

roughened with spots of white or yellow and the lower surface white. 

Thrips 

Both nymphs and adults do the damage by feeding on leaves and cutting seedling. 

Adults are slender, yellowish brown and measure about 1mm in length. Males wingless, 

whereas females have long narrow strap- like wings. The eggs are laid in the tissues of 

tender foliage and the development occurs within the leaf -sheath and nymphs and adults 

feed on the leaves. The damage is caused by both nymphs and adults by sucking sap from 

the tender leaves, causing characteristic whitish streaks. 

Helicoverpa armigera 

Helicoverpa armigera is frequently found in winter cereals but usually numbers are too 

low to warrant control. Occasionally, however, its number may be sufficient to cause economic 

damage. Helicoverpa larvae in cereals (barley, wheat, triticale, oats and maize) tend to feed 

on the exposed tips of developing grains. Rather than totally consuming a low number or 

187

whole grains, they damage a larger number of grains, thus increasing the potential losses. 

Most of the feeding will be during the final two instars. 

Stem borer, Chilo partellus 

This is the most serious pest of maize and its incidence has been reported up to 70 per 

cent. It is many times more harmful pest than all the rest collectively. The maize borer 

attacks every part of maize plant except roots. Newly hatched larvae first scrap the central 

leaves of the whorl and soon tunnel into the stem through the whorl. The new emerging 

leaves of the whorl show small pin holes and scraped leaf injury. Grown up larvae produce 

bigger holes in the whorl leaves. The severe attack results in drying of central whorl of the 

plant, which is known as dead heart. The older larvae may also enter the stem directly. Such 

dead-hearts with plants do not show usual leaf injury symptoms. The plants, showing deadhearts, 

remain stunted in growth, produce tillers and do not bear any ears. The larvae also 

damage the emerging tassels, silks and developing grains in the ears. 

Cutworm, Agrotis spp. 

Cutworms are larvae of noctuid moths. The typical cutworm found attacking the corn has 

a plump, curled-up appearance. The colour of larvae varies with the species from the light 

glassy to a greyish black or brown. Larvae feed at night and their presence in the soil is 

indicated by plants cut off at or below the surface of the ground. This is generally observed 

during rabi season in Bihar and Southern Peninsula. It cuts the emerging seedlings at the 

base of the shoot. This results in complete loss of the plant. 

Armyworm Mythimna separata 

The full grown caterpillar is stout up to about 4 cm long, dusky brown in color with pale 

and brown longitudinal stripes, the dorsolateral stripes being broken into spots. The outbreak 

of this pest occurs suddenly and farmers generally notice it after it has already caused 

considerable damage. The caterpillars generally feed at night and hide in whorls of plants 

during daytime. The caterpillars march from field to field and voraciously feed on foliage. 

They appear after heavy rains or early floods. 

Corn leaf aphid, Rhopalosiphum maidis 

The corn leaf aphid is widely distributed and is occasionally found in large numbers on 

corn. The corn leaf aphid is a small, bluish-green aphid. The aphids may be found in clusters 

on leaves and down in the whorl. Nymphs and adults suck the sap from the leaves and 

shoots, exude honeydew, on which a sooty mold grows, giving the leaves a black appearance 

and interfering with photosynthesis. Infected plants may become stunted and turn reddish 

as they mature. If young plants infected they seldom produce ears. Ears and shoots are 

also infested and seed set may be affected. 

Shoot fly, Atherigona soccata, A.naqvii 

It is a very serious pest of maize in South India but also severally damages spring and 

summer maize crop in North India. The attack is maximum when the crop is in seedling 

stage. The tiny maggots creep down under the leaf sheaths till they reach the base of the 

seedlings. After this they cut the growing point or central shoot which results in the formation 

of characteristic dead hearts. 

188

Assessment of losses 

The following methods have been suggested on the basis of various techniques developed 

so far for estimating the losses caused by insect pests. 

i) Mechanical Protection of the crop from pest damage : Efforts may be made 

to grow the crop under cages of various material to keep out the pest, and then to 

compare the crop yield with that obtained from infested crop grown under infested 

conditions. 

ii) Chemical protection of crop from the pests under investigation : The 

experimental crop may be protected by applying recommended insecticides 

schedule, and the yield is compared with that under normal insect infestation. 

This technique is widely used for estimating the losses caused by insect pests. 

Percent avoidable loss+ y-y’/yx100 

Where, y and y’ are the mean yields in the protected and unprotected plots, 

respectively. 

iii) Comparison of the yield in field having different degrees of pest infestation: 

Under this method different degrees of pest infestation is to be maintained by 

applying the insecticide at various intervals and then to work out yield losses. 


Aggarwal, S. Insect Pest of Cereals and their Management. Published by Oxford Book 

Company. 

Corn Insect Pest-A Diagnostic guide. Published by MU Extension, University of Missouri, 

Colombia. 

Wheat disease and Pests: a Guide of Field Identification. Published by International Maize 

and Wheat Improvement Centre. 

189


LOSSES DUE TO INSECT-PESTS IN STORED GRAINS 

S. S. Sharma 



The stored grains, whether in homes, farms or warehouses are prone to attack of various 

types of pests which not only result in quantity loss but in quality also. In storage, loss to 

the extent of approximately 9.33 per cent has been estimated to occur because of various 

agents. Prior to their management the knowledge related to their identification, nature of 

damage, insect infestation and the amount of loss caused the particular pest is essential. 

The available information on the above aspects is summarized below: 

Rice weevil : Sitophilus oryzae (Linnaeus), Sitophilus granarius 

F : Curculionidae O : Coleoptera 

The weevil is reddish brown, chocolate to almost black in colour, having a characteristic 

beak or snout.. The legless fleshy and curved larva remains in grains Pupation takes place 

inside the grain. Adult comes out leaving a circular hole on the grain. Both the adults and 

larvae damage the grains. The grains become hollow. The heating of grain takes place due 

to severe infestation of this pest. 

Lesser Grain Borer : Rhyzopertha dominica (Fabricius) Bostrychidae : Coleoptera 

The adult beetle is blackish brown There is a prominent constriction between prothorax 

and elytra and the head is deflexed downwards, which seems to be almost hidden from the 

dorsal view. The larvae are legged, can crawl, feed on grains and enter the grains after the 

third instar. The pupation within the grain or grain dust. Both the adults and grubs cause 

damage to the grains, which are reduced to mere shells. The damaged kernels remain 

engulfed in a film of waste flour. The adults are good flier and produce a considerable amount 

of frass, which serves as a nourishment for the young ones until they are ready to bore into 

the grain. 

Larger Grain Borer, Prostephanus truncatus (Fabricius) F : Bostrychidae O : Coleoptera 

It is found in maize growing areas of America and Africa. Larva feeds in maize grains and 

can fly and attacks other food stuffs. 

Khapra beetle : Trogoderma granarium Everts Dermestidae : Coleoptera 

Adults are short lived and harmless. Grubs are straw coloured, hairy with dark brown 

bands on each segment and a typical posterior tuft forming a tail of long hairs, which move 

actively and freely. They damage the grains starting from the germ portion, surface scratching 

and devour the grains and usually confined to the upper 50 mm layer of the grains. In severe 

infestation they completely destroy the grains, reducing them to a mere frass. Unhygienic 

conditions created by the cast skins, frass and hairs reduce marketability Crowding of 

larvae lead to unhygienic conditions in warehouses. 

Rusty grain beetle, Cryptolestes ferrugineus (Steph.) , Cryptolestes pusillus (Schonherr), 

Red rust grain beetle, Laemophloeus pusillus F : Cucujidae O : Coleoptera 

The adult is a shiny reddish brown beetle, moves rapidly in warm grain. Normally secondary 

pest but also attacks damaged whole grains. The larvae and adults feed on the germ and 

endosperm. Heavy infestations of the insects also contribute to other damage by causing 

the grain to heat and spoil, and by spreading fungal spores in the stored grain. 

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Saw toothed grain beetle (Oryzaephilus surinamensis), 

Merchant grain beetle (Oryzaephilus mercator) F : Silvanidae O : Coleoptera 

Larva develops rapidly, particularly at high moisture contents (more than 14%). On wheatfeed, 

the larva of O. mercator grows more slowly than that of O. surinamensis and was more 

sensitive to low humidities. Adult is long lived can survive up to three years. It is a 

cosmopolitan pest and important pest of many stored products, secondary pest of whole 

grains: Adults and larvae cause roughing of grain surface and off colour in grains, leads to 

broken of grains and heating of grains. Feeds on rice, wheat, maize, cereal products, oil 

seeds and dry fruits. Both species can increase rapidly in the tropics. O. surinamensis is a 

pest because it can survive in large numbers in the fabric of warehouses and multiply rapidly 

when warm or actively heating produce becomes available. 

Flat Grain beetle, Latheticus oryzea Waterhouse F : Tenebrionidae O : Coleoptera 

Small yellowish brown beetle with flat slender body with parallel sides. Adults live up to 

six months. Longheaded Flour Beetle is a pest of grain products in tropical and sub-tropical 

regions of the world but minor pest of wheat, barley, corn, flour, cereals, oatmeal, and also 

beans. Adults and larvae feed on stored products. It is an important pest of milled rice, 

maize, wheat, broken grains, different flours or groundnut Larva feeds on germ portion or on 

dead insects, adults are scavenger, cause heating in grains. 

Red rust flour beetle : Tribolium castaneum (Herbst), Tribolium confusum 

Tenebrionidae : Coleoptera 

Beetle is oblong, brown. Both the larva and adult damage the broken grains, milled 

products, flour and the germ portion of the healthy seeds. Heavy infestation in flour causes 

stinking odour, which adversely affects the quality. 

Gram dhora (Bruchus chinensis) and pulse dhora (moong Dhora) Callosobruchus 

maculatus (Linnaeus) Bruchidae : Coleoptera 

The beetle is small, squat, active, long conspicuous, serrated antennae with brownish 

grey colour and elevated ivory like spots near the middle of the dorsal side. Elytra don’t 

cover the abdomen completely.Grub just after hatching penetrates into the grain and completesfull 

life inside it and damages the grain kernel by making cavities in them. It is fleshy, 

curved, white, creamy in colour with black mouthparts. Pupation in the pupal cell made 

under the seed coat. Adults are short lived and don’t feed on stored products at all. 

Dried bean beetle (Acanthoscelides obtectus Say) F : Bruchidae O : Coleoptera 

Just after hatching the young grub enters into the pulse grain, feeds inside and forms a 

characteristic window before pupation to form an exit hole for adult emergence. Grub is the 

only damaging stage damage. 

Cigarette beetle : Lasioderma serricorne Fabricius Anobiidae : Coleoptera 

The light brown shinning round beetle has its thorax and head bent downward, which 

gives a humped appearance. The elytra have minute hairs on them. grubs and pupae are 

creamy white. Both beetles and grubs are harmful, feed on stored tobacco, cigarettes, ginger, 

turmeric and chilies, etc. by making holes in them. 

Angoumois grain moth : Sitotroga cerealella (Olivier) Gelechidae : Lepidoptera 

Moth is dirty yellowish brown with wings completely folded over back in a sloping manner. 

Hind wings with sharp pointing apical end and bearing heavy fringe of bristles that leaves 

small specks on window pans and walls. Larva is white in colour with yellow head. Only the 

larvae cause damage by feeding on the grains,bores into the grain and feeds on its contents. 

The damaged grains are hollowed. Attacks paddy, maize, jowar, barley and wheat. As the 

191

larva grows, it extends the hole, which partly gets filled with pellets of excreta. When the 

infestation is high, the upper layer is most severely infested. 

Rice moth : Corcyra cephalonica (Stainton) Pyrallidae : Lepidoptera 

The spot free uniformly pale buff brown coloured adult is the biggest amongst foodgrain 

infesting moths. Larva feeds on grains, pollutes the food grains with frass, moults and dense 

webbing, pollutes with frass, moults, kernels are bound into lumps. 

Meal moth , Ephestia kuhniella Walker F : Pyralidae O : Lepidoptera 

It is a pest of temperate area; attacks cereal products particularly flour; larva favours 

flour dust and forms heavy webbing which can even choke the machinery. 

Warehouse Cocoa Tobacco moth, (Ephestia cautella) 

It is a pest of temperate area; attacks raw and processed products of peanuts, kernels 

of tree beans ,stored grain,, dried fruit, wheat, rice, maize, jowar, groundnut, spices. 

Larva move to and over the produce feeding and spinnig threads and forming the web. 

Heavy web formation leads to clogging in mill 

Indian meal moth, Plodia interpunctella Huebn. F : Phycitidae O : Lepidoptera 

Mature larvae often wander away from the food source in search of pupation sites. Adult 

are short lived. Larva damages the grains preferably the germ portion, and contaminate the 

grains with excretement, cast skins, webbing, dead individuals, cocoon. 

Methods of detection of insect infestation in stored grains 

a) Detection of visible infestation 

1. Sieving : By sieving the grains with 10-16 mesh sieve the adult beetles present in 

grains can be collected below the sieve. 

2. Agitation of sacks : Bags of grains are thrown up and downwards several times 

thus adult beetle can be collected. 

3. Disturbance of stacks or bulk surfaces : A long stick can be moved over and 

vertical fashion on stack and the fallen adult beetles can be collected. 

4. The feel of grain in bulk : Through walking over the bulk of grains if a hot spot is 

there or fairly solid patch means problem. 

5. Probe Trap : Trap is kept vertically in the grains with top cap at grain level, the 

insect will enter in it through holes and will be collected in the trapping tube. 

6. Pit fall trap : This trap can be placed in metal bean or small container or utensil 

used for storage of grains beetles are trapped in this pit fall trap. 

7. Light trap for grain storage godowns : The UV light traps and ultra violet traps 

are used to attract the beetles. 

8. Sticky traps : Fly paper type or sticky trap are commonly used in the storage. The 

adults get stick on the sticky material. 

9. Artificial crevices 10. Dead insects: 

11. Grain temperature and moisture contents : Hot spots are the result of heavy 

insect infestations. 

12. White spots : White spots outside the grain bags and molts of the larvae also 

indicate the insect infestation. 

b) Detection of hidden infestation : 

a) Use of acid infestation 

b) Gentian violet and Berbeine sulphate 

c) Floatation or density method 

192

DIAGNOSTIC SYMPTOMS OF INSECT-PESTS' DAMAGE IN STORED GRAINS 

Rice weevil in wheat Khapra in wheat 

Angoumois grain moth on 

maize 

Lesser grain borer Rust red flour beetle 

Cigarette beetle in coriander Pulse beetle in rajmash 

Pulse beetle in chickpea and 

pea

d) Gelatinization method 

e) Cracking floatation method 

f) Spectrophotometric analysis g) Ninhydrin colour reaction 

h) Carbondioxide determination method 

i) X-Ray radiographic method 

Method of loss assessment 

Prior to the determination of losses in grains due to insect’s the following steps need to 

be undertaken: 

Step-1 Sieving of grains : To make the sample free from insects dusts it should be first 

winnowed and sieved through the normal grain sieve. 

Step-II Determination of original grain condition : Determination of baseline condition 

of grain is essential. The moisture should be estimated in a particular grain because 

the volume and weight can change with the varying degree of moisture or take a 

visibly undamaged/healthy grain sample replicated thrice, put them in jar covered 

with muslin for four weeks. If there is no damage calculate the value and it there is 

damage, take the samples with 5% or less damaged kernels. 

Step-III Preparation of baseline determination : Take 5 kg grain sample from each lot, 

sieve it. Determine the moisture content, dry the sample in shallow layer with 

warm and dry air over it or in an oven below 35Úc and when the moisture goes 

below 10%, place it in sealed container to cool down and measure the accurate 

moisture content or place a small known weight sample in oven and check the 

weight loss after drying. 

QUANTITATIVE LOSS DETERMINATION : 

There are four methods for determination of losses to grains. 

1. Standard volume/mass method : This technique relies on the assumption that the 

volume occupied by the same number of damaged or non damaged grains will be identical, 

but the mass of this standard volume will decrease as the level of damage increases. The 

relationship between the dry mass and the moisture content of the standard volume of non 

damaged grain at the time of storing is plotted on a graph. The dry mass of standard volumes 

of grain from later samples can then be compared to that of the initial sample, and the 

percentage mass loss calculated. 

D1-DX 

Per cent dry mass loss = —————— x 100 

D1 

Where 

D1 = Dry mass of standard volume at the beginning of the experiment (read from the 

graph using the same moisture content as that obtained for DX). 

DX = Dry mass on occasion X 

2. Modified standard volume/weight method 

Procedure : To use this method an artificial baseline is prepared by selecting healthy 

samples from the grain in the store at the time of determination. The loss is the difference in 

weight (%age) between the undamaged and damaged sample. Here the moisture content of 

damaged and undamaged is the same. 

Percent grain loss in wt = Wt. of undamaged grain –weight of damaged grains x 100 

Wt. of undamaged grains 

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3. Thousand-grain mass (TGM) method : Here a sample taken when the grains are placed 

in store is weighed, the number of grains is counted and their moisture content is determined. 

The dry mass of 1000 grains is obtained by the following formula. 

1000 x m x (100-H) 

Thousand-grain mass TGM = ———————————— 

N x 100 

Where: 

m = wet mass of the working sample, H= Percentage moisture content of the grain and 

N= number of grains in the working sample. 

M1-MX 

Per cent dry mass loss = ————— x 100 

M1 

where, 

M1= TGM of the grains at the beginning of the study and MX= TGM of the grain on 

occasion X. 

4. Count and weigh method 

Procedure : Take a grain sample from the store. Separate the damaged and undamaged 

grains count and weight the damaged undamaged grain separately and put the data in the 

following formula. 

(Dry mass of nondamaged grains x number of damaged grains) – 

(Dry mass of damaged grains x number of nondamaged grains) 

Percent weight loss = ——————————————————————————— x 100 

Dry mass of nondamaged grains (number of damaged grains + 

number of nondamaged grains) 

Sample size should be 100-1000 grains. 

Drawback : Hidden infestation results in an underestimation of loss and heavily infested 

grains or broken grains lead to counting error. 

POST HARVEST LOSSES IN GRAINS 

During storage both quantitative and qualitative losses occur due to insects, rodents, 

and microorganisms. A large number of insect pests are associated with stored grains which 

are directly related to geographical and climatic conditions. There are different estimates on 

post harvest losses in food. Almost all the insect species may destroy 10.0 - 15.0 % of grain 

and contaminate with undesirable odour. They also help in transportation of fungi (Sinha and 

Sinha, 1990). According to Word Bank report 1999, post harvest losses of food grains in 

India amount to be 12-16 metric tonns of food grains each year costing 500-600 crores. 

Losses due to insect s in storage is 70 kg/ton (7%) (Anonymous, 2001). 

Farmers retain about 60-70% of their produce for the purpose of home consumption and 

for sale. The loss of grains stored as seed and future food of India is to the tone of 7-8% (Rs 

600-700 crores). As per the Directorate of Marketing and Inspection, the estimated total 

post harvest losses in food grains at producer level has been 1.79 % and 10% of wheat 

production in colossal which works out to Rs 35 million. In other report the post harvest loss 

of wheat have been estimated to the tone of 8% of the total production. According to the 

Report of the Committee on Post Harvest Losses of Food Grains in India, Ministry of Food 

and Agriculture, Govt of India (1971). the losses at different levels as at threshing 1.0 %, 

transportation 0.5 %, rodents 2.5 %, birds 0.5 %, insects 3.0 % and moisture 0.5% and 

194

total loss is 8.0 %. In other report of FAO, the major loss by biotic and abiotic factors is 

10% and the major loss is done by two internal feeders i.e. rice weevil and grain borer which 

are major pests of rice, wheat and millets (Chap and Dyte, 1977). Rice weevil alone causes 

loss of 61.3% of sorghum grains (Venkat Rao et al., 1958). However, in sorghum grain 

weight losses after 180 days of storage was I2.08 - 20.01 %. This insect feeding on rice 

grains causes 5-25% weight loss and 20-50 % loss on seed viability in paddy (Anand Parkash 

and Rao, 2001). In India, estimated loss due to stored pests are about 10.0% (Dhuri, 2006). 

Loss in maize in Karnataka during various factors in storage is 21.86%. 


Anonymous, 2001. Manual on Grain Storage at Farm Level. Report of Storage & Research 

Division, Department of Food & Public Distribution, Ministry of Consumer Affairs, Food 

& Public Distribution, Government of India. 

Ashman, F. 1973. Methods and techniques of assessing quality in stored products. Tropical 

Stored Products Information 25 : 33-35. 

Basappa, g., Deshmanya, J.B and Patil, B. L. 2007. Post- Harvest Losses of Maize Crop 

in Karnataka - An Economic Analysis. Karnataka J. Agric. Sci., 20(1) : 69 – 71. 

Dhuri, A.V. 2006. Fumicover An effort in reducing losses in stored grains at farm Levels. 

9th International Working Conference on Stored Product Protection at Rome. PS6-15 – 

6184: 612 

Dick, K.M. 1987. Pest Management in Stored Groundnuts. ICRISAT Bulletin no. 2. Patancheru 

Hyderabad (AP).India. 

Golob, P. 1976. Techniques for sampling bagged produce. Tropical Stored Products 

Information 31 : 37-48. 

Harris, K.L., and Lindblad, C.J. (eds.) 1978. Postharvest grain loss assessment methods. 

St. Paul, Minnesota, USA: American Association of Cereal Chemists. 193 pp. 

Howe R. W. 1956. The biology of the two common storage species of Oryzaephilus 

(Coleoptera, Cucujidae). Annals of Applied Biology 44 (2) : 341–355. 

Howe, R.W. 1965. Losses caused by insects and mites in stored foods and feeding staffs. 

Nutrition Abstracts and Reviews 35 : 285-293. 

Loschiavo, S.R., and Atkinson, J.M. 1973. An improved trap to detect beetles (Coleoptera) 

in stored grain. Canadian Entomology 105 : 437-440. 

Narain, P., and Khosla, R.K. 1984. Estimation of post-harvest food grain losses. Journal of 

the Indian Society of Agricultural Statisitics 36 (1) : 127-142. 

Proctor, D.L., and Rowley, J.Q. 1983. The thousand grain mass (TGM) method: a basis for 

better assessment of weight losses in stored grain. Tropical Stored Products Information 

45 : 19-23. 

Pruthi ,H.S. and Singh, M. 1948.Pests of stored grain and their control. Indian Journal of 

Agricultural Science 18 (4) : 1-86. (Special issue). 

Sinha, A.K. Sinha, K.K. (1990). Insect pests Aspergillus flavus and aflatoxin contamination 

in stored wheat: a survey at north Bihar (INDIA). Journal of Stored Products Research 

26 (4) : 223-236. 

195

MOLECULAR MARKERS : CONCEPTS AND 

THEIR APPLICATIONS IN ENTOMOLOGY 

A. K. Chhabra 

Department of Plant Breeding, 


Introduction to Marker Systems 

Marker : A marker can be anything that guides/ 

helps you to achieve a target. For example, a tree 

or a building can act as a marker if it gives you 

directions to reach your destination while on road. 

Phenotypic markers are those markers, the 

presence of which may indicate the presence or 

absence of any other linked / co-inherited trait. For 

Example, the presence of hair or the presence of 

bristles in pearl millet make the crop insect and 

bird resistant respectively. DNA markers are the 

fragments of DNA that co-segregate with any trait, 

but not necessarily code for those genes. These 

are alleles of loci at which there is sequence 

variation - or polymorphism - in DNA that is neutral 

in terms of phenotype Fig. 1 (hypothetical 

example) clearly shows what molecular marker 

exactly means and how linkage maps created 

through them help in marker-assisted selection. 

Morphological or phenotypic markers are 

traditional markers that are recognized by visual 

observation of the phenotype in the field or 

laboratory. If phenotypic characters (markers) are 

not available (mono-/oligo-genic), the alternatives 

are the biochemical and molecular markers. 

Types of molecular markers 

Protein markers 

The beginners in the area of molecular markers, particularly 

with limited resources start with protein analysis. Protein 

markers, including seed storage proteins, structural proteins, 

and isozymes. These were among the first group of molecular 

markers exploited for genetic diversity assessment and 

construction of genetic linkage maps. They are also some of 

the most cost-effective tools for data point generation, especially 

when iso-electric focusing equipment is used to precisely 

distinguish between very similar versions of proteins. 

Limitations : 

The major limitations of these markers are - that much of Protein Electrophoresis 

the genome (including much of the most polymorphic portions of it that are less subject 

to evolutionary restrictions) does not code for genes. 

196

Different biochemical procedures are required to visualize polymorphism for enzymes 

having different functions. 

DNA markers 

Most points on molecular marker-based genetic linkage maps are anonymous DNA 

polymorphisms (e.g., RFLP, AFLP, SSR, SNP markers etc.) and do not correspond to any 

gene of known function. However, some molecular markers (including cDNA and ESTs) 

markers, as well as the protein markers described above) do pinpoint individual genes. 

Anonymous DNA markers are generated by a wide variety of techniques, differing greatly in 

their reliability, difficulty, expense, and the nature of the polymorphism that they detect. 

RAPD : (Random Amplified Polymorphic DNA), This PCR-based technique requires neither 

cloning nor sequencing of DNA. A random amplification of anonymous loci by PCR 

(polymerase chain reaction – amplification of DNA fragments that may be unique to a loci or 

gene). In the process, many bands (e.g. 30 or more) might appear simultaneously on the 

electrophoretic gel, some of which are not constant from individual to individual. RAPD 

markers allow creation of genomic markers from species of which little is known about 

target sequences to be amplified. 

AFLP (Amplified Fragment Length Polymorphism) : This PCRbased 

technique requires no sequencing or cloning. It is combination of 

both RFLP and RAPD as it uses primers and also Restriction Digestion of 

the chromosomes. DNA is cut with restriction enzymes and short 

fragments that support PCR which are added to the cut ends. PCR is then 

performed to produce many fragments, some of which vary in length from 

individual to individual (polymorphic) and is based upon tightly linked 

markers flanking the desired gene locus (positional cloning). So it is usually 

interpreted as dominantly inherited, although reports of co-dominant 

inheritance are also in the literature. AFLP markers are often inherited as 

tightly linked clusters in centromeric and telomeric regions of 

chromosomes, but randomly distributed AFLP markers also occur outside 

these clusters. The technique is difficult to master and is less appropriate 

than others for comparative mapping studies. 

CAPS (Cleaved Amplified Polymorphic Sequences) : These 

secondary markers are identified with two oligonucleotide primers 

synthesised on the basis of known DNA sequences. Like SCAR primers 

(see below), they specifically amplify single fragments. However, 

polymorphism of CAPS is revealed by pre-amplification digestion of 

template DNA with several restriction endonucleases. 

CHROMOSOME 

AFLPs are 

generally 

clustered at 

centromere or 

telomere 

DAF (DNA Amplification Fingerprint) : In this modification of the RAPD technique, 

one or more 7- to 8-nucleotide primers are used to produce a relatively complex pattern. 

Amplification products are separated electro-phoretically and visualised by silver staining. 

Digestion of template DNA with 1 to 3 restriction endonucleases enhances amplification of 

polymorphic DNA, allowing even near-isogenic lines to be distinguished. 

EST (Expressed Sequence Tag) : An expressed sequence tag or EST is a short subsequence 

of a transcribed protein-coding or non-protein coding DNA sequence. It was originally 

intended as a way to identify gene transcripts, but has since been instrumental in gene 

discovery and sequence determination. An EST is produced by one-shot sequencing of a 

197

cloned mRNA, and the resulting sequence is a relatively low quality fragment whose length 

is limited by current technology to approximately 500 to 800 nucleotides. ESTs are also a 

useful resource for designing probes for DNA microarrays used to determine gene expression. 

This PCR-based approach requires both cloning and sequence information. As part of 

gene sequencing projects, partial sequences of cDNA clones are generated. These are then 

used to design 18-20 base pair primers that provide a unique sequence “tagging” the gene. 

It detects a unique, expressed region of the genome. 

Microsatellite or STR’s (Short Tandem Repeats) : A microsatellite is a simple DNA 

sequence that is repeated several times at various points in the organism’s DNA. Such 

repeats are highly variable enabling that location 

(polymorphic locus or loci) to be tagged or used 

as a marker. This has quantitative value when the 

location is associated with gene traits of value or 

importance. Microsatellites have much more 

information than allozymes, yet offer the same 

advantages of analysis. Ambiguity (RAPD’s and 

AFLP’s), or scarcity (RFLP’s) are not a problem with microsatellites, given appropriate 

enrichment technologies.These PCR-based markers can require considerable investment to 

generate, but are then highly polymorphic and inexpensive to use in mapping and MAS. 

Advantages of SSRs : 

Co-dominant (more informative when dealing with heterozygotes) 

Highly variable (important for species with narrow gene pools) 

Widely used 

Excellent for use in marker assisted selection, fingerprinting and marker assisted 

backcrossing 

Disadvantages : 

Moderate throughput level - efficiency can be increased by “multiplexing” (using more 

than one SSR marker per reaction) 

RFLP (restriction fragment length polymorphism) 

Gel photo of SSR markers population 

RFLP is polymorphism represented by the presence or absence of “restriction” sites, 

which are short sequences along the DNA that can be cut by commercially available “restriction 

enzymes.” Mutations (alterations in the DNA sequence) change the locations along the 

genome where these enzymes cleave the DNA. The length of the cut fragment depends on 

whether particular restriction sites are present or not (polymorphic). The presence and absence 

of fragments resulting from changes in recognition sites are used to identify species or 

populations. This is the oldest DNA-based method for finding polymorphic loci, (which are 

difficult to find using this methodology), and the analysis may be awkward. The technique 

requires large amounts of DNA material which may be invasive and lethal to small aquatic 

organisms. 

This hybridisation-based technique requires use of a library of DNA fragments cloned 

into some vector. These fragments may be from the species under study or from related 

(even distantly related) species. The library may be based on genomic or cDNA. RFLP does 

not require sequencing. The DNA of the organisms under study are digested with one or 

more restriction endonucleases, the resulting fragments separated electrophoretically 

according to size, and probed with DNA clones from the library. Fragments matching the 

198

probe DNA are visualised by autoradiography or the use of fluorescent labelling techniques. 

The radioactive label-based visualisation methods are robust and allow multiple uses of the 

DNA separations resulting from a single restriction digest and electrophoresis run. 

SCAR(Sequence-Characterized Amplified Region) 

These PCR-based secondary markers 

are detected with two 24-nucleotide primers 

homologous to sequenced ends of a RAPD 

marker. They amplify a single fragment with 

high reproducibility. Many are co-dominant 

and their polymorphism can often be 

increased by digesting the PCR product 

with restriction enzymes having 4nucleotide 

binding sites. 

SSCP (single-strand conformation 

polymorphism) 

http://www.bio.davidson.edu/Courses/ 

Molbio/MolStudents /spring2003/Parker/method.html 

Fig. : Sample SSCP Gel Result and Interpretation. DNA was isolated and amplified from sand 

flies (Lutzomyia longipalpis). SCCP analysis of the DNA shows multiple haplotypes, or sets of 

alleles usually inherited as a unit. Lanes 3 and 4 were identical haplotypes from two individuals. 

The difference in band migration in adjacent lanes is associated with the number of 

nucleotide differences (in parentheses): lanes 2-3 (2), lanes 3-4 (0), lanes 4-5 (3), lanes 5- 

6 (1), lanes 6-7 (3), lanes 7-8 (1), lanes 8-9 (1), and lanes 9-10 (4).Source: Hodgkinson, 

et al,. 2002 (Journal of Medical Entomology Volume: 39 Issue: 4 Pages: 689-694) 

SSCP is the electrophoretic separation of single-stranded nucleic acids based on subtle 

differences in sequence (often a single base pair) which results in a different secondary 

structure and a measurable difference in mobility through a gel. 

Principle Involved : The mobility of double-stranded DNA in gel electrophoresis is 

dependent on strand size and length but is relatively independent of the particular nucleotide 

sequence. The mobility of single strands, however, is noticeably affected by very small 

changes in sequence, possibly one changed nucleotide out of several hundred. Small changes 

are noticeable because of the relatively unstable nature of single-stranded DNA; in the absence 

of a complementary strand, the single strand may experience intrastrand base pairing, 

resulting in loops and folds that give the single strand a unique 3D structure, regardless of 

its length. A single nucleotide change could dramatically affect the strand’s mobility through 

a gel by altering the intrastrand base pairing and its resulting 3D conformation . 

SSCP Limitations and Considerations 

Single-stranded DNA mobilities are dependent on temperature. For best results, gel 

electrophoresis must be run in a constant temperature. 

Sensitivity of SSCP is affected by pH. Double-stranded DNA fragments are usually 

denatured by exposure to basic conditions: a high pH. 

Fragment length also affects SSCP analysis. For optimal results, DNA fragment size 

should fall within the range of 150 to 300 bp, although SSCP analysis of RNA allows for 

a larger fragment size. The presence of glycerol in the gel may also allow a larger DNA 

fragment size at acceptable sensitivity. 

199

Under optimal conditions, approximately 80 to 90% of the potential base exchanges are 

detectable by SSCP. 

If the specific nucleotide responsible for the mobility difference is known, a similar 

technique called Single Nucleotide Polymorphism (SNP) may be applied. 

STS (Sequence-Tagged Site) : These PCR-based markers detect a single, unique, sequencedefined 

point in the genome. They are obtained by sequencing terminal regions of genomic 

fragments and cDNAs expressing RFLP. Primers of 18-20 base pairs are designed to amplify this 

short, unique fragment. Polymorphism is often reduced compared to the original RFLP marker, 

but can be increased at some additional cost by restricting the PCR products to increase the 

number of bands detected. Since they are longer than RAPD primers and based on a specific 

sequence, STS markers more reliably detect the same locus. They are good for both mapping 

studies and MAS, provided that polymorphism detected is adequate. 

METHODS TO DETECT SNPs : 

Allele Specific PCR: Appropriately designed PCR primers can be used to discriminate 

SNP alleles. In the assay developed by See et al., (2000) in barley, two primers are labeled 

with different fluorophores at their 5' nucleotides with their 3' termini match each of the SNP 

alleles. The PCR is performed using two labeled forward primers and an unlabeled, common 

reverse primer. A separate pre-amplification step reduces the complexity many folds and 

may be a necessary step in large genomes. Each primer perfectly matches one of the two 

available alleles and the alleles can be scored based on fluorescence spectrum or size of 

the PCR product size. Although the technique is simple, the throughput is not very high. 

Allele Specific Hybridization : In allele specific oligonucleotide hybridization (ASO or 

ASH) technique the target PCR product is immobilized and denatured to a membrane and 

hybridized with allele specific oligonucleotides. An oligonucleotide that is complementary 

to one of the alleles will hybridize to that allele and the other allelic variant will hydridize 

with its specific complimentary probe. The detection of the hybridized probe is by radiolabel, 

fluorophore or biotin assay. In a variation of this assay oligonucleotides can be immobilized 

(instead of amplified targets) and probed with labeled PCR products of the samples. 

Fluorescence Resonance Energy Transfer (FRET) Based Methods : The TaqMan 

(PE Biosystems) and Molecular Beacons are the homogenous SNP genotyping assays that 

depend on fluorescence energy transfer. The TaqMan assay uses the exonuclease activity 

of Taq polymerase to discriminate between perfectly matched and mismatched 

oligonucleotides (Heid et al., 1996). In TaqMan assay, fluorogenic oligonucleotide probes 

are synthesized with a fluorescent reporter dye at the 5' terminus and the 3' terminus contains 

a blocking group to prevent probe extension and a quencher that inhibits the fluorescence of 

the reporter. The taq-polymerase during its polymerization step in PCR encounters the 

annealed probe and begins to displace it. This leads to clipping of the probe by the nuclease 

activity of the enzyme and results in increased fluorescence. The presence of an allele is 

deciphered by monitoring increase of the fluorescence resulting from the separation of 

fluorophore from the quencher. Hundreds of samples can be analyzed simultaneously, and 

there is no need of downstream electrophoresis. 

Pyrosequencing : Pyrosequencing allows short segments of sequence, typically of 20 

nucleotides, and possibly up to 100 nucleotides to be obtained in an automated manner. In 

the present configuration, up to 96 different templates can be sequenced simultaneously in 

15 minutes after template preparation. Pyrosequencing relies on the stepwise addition of 

individual dNTPs and sequencing-by-synthesis (Nyren et al., 1993). The template-guided 

incorporation of dNTPs into the growing DNA chain is monitored via luminescent detection of 

released pyrophosphate from the incorporation reaction. Genotyping of previously identified 

200

SNPs requires only a small stretch of sequence beyond the primer binding site, and 

pyrosequencing handles this very efficiently. The procedure involves designing sequencingprimers 

close to the identified SNP sites, PCR amplifying the SNP loci, obtaining single 

stranded template, and sequencing several bases including the target SNP site using Luc96 

pyrosequencer. 

Third Wave Technology : Third Wave Technologies, Inc developed an enzyme-based 

system of genetic identification that utilizes the property of cleavase enzyme (Lyamichev et 

al., 1999). The assay is known as CFLP (Cleavase Fragment Length Polymorphism) and it 

makes use of the specific sequence-dependant secondary structures containing duplexed 

and single stranded regions. The cleavase recognizes these sequences and produces 

fragments after cleaving the junction of the duplexed region. This technology does not involve 

a PCR amplification step and thus reduces assay costs and the artifacts that can be introduced 

during PCR. 

Array Based Hybridization : The SNP genotyping can be performed using a very highdensity 

gene chips. The user-defined chips are available for human SNP analysis by variety 

of manufacturers. DNA chip or SNP chip of Affymetrix, for example, contains precisely 

ordered arrays of oligonucleotides synthesized in situ on a (glass or) silica-wafer. This can 

accommodate as many as 60,000 oligonucleotide probes and can be used to screen as 

many as 1500 human SNPs simultaneously (Lipshutz et al., 1999). The procedure involves 

PCR amplification of the target, hybridization to the oligonucleotides on the chip, scanning 

the chip to see which probe produces the signal, and analyzing the data. The genotype is 

determined based on the probe sequences that show strongest hybridization signal, according 

to a proprietary algorithm. Highly multiplex PCR is necessary to take full advantage of the 

capacity of chips to assay multiple loci. 

Single Base Extension - Fluorescent Polarization (SBE-FP) Assay : The fluorescent 

polarization assay method for detecting SNPs is a variation of the template-directed dye 

terminator incorporation assay, that is detected using fluorescence polarization and was 

developed recently (Chen et al., 1999). This method involves an oligonucleotide probe that 

hybridizes immediately upstream of the SNP site. All the four ddNTPs, each labeled with a 

different fluor is added followed by DNA polymerase and the probe is allowed to extend by a 

single base. Fluorescence depolarization is then used to determine which ddNTP was 

incorporated. The advantages of this method are the speed and accuracy of SNP detection, 

the low cost and the ability to rapidly genotype many targets. 

Denaturing High Performance Liquid Chromatography (DHPLC) : DHPLC is a 

mismatch detection technology that relies on differences in physical properties between 

DNA homoduplexes and mismatched heteroduplexes formed during the annealing of wild 

type and mutant DNA (Oefner and Underhill, 1998). The procedure is also called temperature 

modulated heteroduplex assay (TMHA) since the method involves heat denaturation of the 

DNA and the subsequent slow cooling at an empirically determined optimal temperature. It 

is during the cooling that heteroduplexes are formed. Homo and hetero duplexes are resolved 

using a proprietary separation matrix. This method does not need any a priori information 

about the SNP, but it only detects the presence or absence of a mutation, but not the nature 

and location of mutation. The major advantage of TMHA is that it does not need modified 

PCR primers, detection labels or any sample pretreatment and still allows some multiplexing 

and a degree of automation. 

Inter MITE Polymorphisms (IMP) : IMP is a technology that is proprietary to DNA 

LandMarks. It is based on the presence of Miniature Inverted-repeat Transposable Elements 

(MITEs) in the plant genome. These elements have several advantageous characteristics: 

201

Very abundant in plants (several thousand copies per genome) 

Highly associated with genes making them excellent markers 

Small size (less than 500 base pairs) 

Each end has an inverted repeat sequence referred to as a terminal inverted repeat (TIR) 

Several distinct MITE families exist - e.g. Tourist-like, Stowaway-like 

Despite the name “transposable elements” they remain relatively fixed in the genome 

Because MITEs are so abundant throughout the genome, IMP markers are based on 

PCr amplification of the DNA in between two MITEs rather than amplifying the marker itself. 

Image generated by an IMP genotype gel : (source of image www.dnalandmarks.ca/ 

marker_systems_overview.html) 

Advantages 

Very efficient - able to generate multiple data points with a single reaction 

Greatly reduces cost of marker assisted backcross programs 

High throughput capability 

Widely adaptable across most plant species 

Excellent for fingerprinting, marker assisted backcrossing and germplasm characterization 

Disadvantages 

Generally dominant marker system 

Direct amplification of length polymorphisms (DALP) : This is a very new method 

that utilizes an arbitrary oligonucleotide addition to universal M13 primers that are used for 

sequencing (Desmarais et al., 1998). It is an innovative system that produces DNA fingerprint 

polymorphisms within a species based on PCR amplification and in some ways, is similar to 

AFLP but has particular advantages, i.e. that it does not involve any restriction or ligation 

steps and polymorphisms viewed on an acrylamide gel can be directly sequenced when 

detected by using the M13 primers. This technique will be very beneficial in quickly screening 

for genetic polymorphisms and allelic variation at given loci, provided that suitable parental 

crossings are performed, but has not as yet been used with insects. 

Choice of marker system : The marker system 

of choice depends on the objective of the study plus 

skills and facilities available in the laboratory, but a 

combination of two or several techniques is 

recommended. Especially AFLPs and SSRs seem to 

complement each other (Milbourne et al. 1997). See 

the table to compare the reliability and use of different 

(common) markers. For direct application by plant 

biologist SSRs possess the best qualities because 

they are very simple to use once they have been 

developed. Still there is a need for more uncomplicated 

techniques that are non-hazardous, cheaper, easier 

to handle and have a larger degree of automation. 

Fluorescent IN SITU Hybridization (FISH 

Source:http://gsc.genetics.uth.edu/units/ 

diorders/karyotype/images/FISH_technique.jpg 

Fluorescent IN SITU Hybridization (FISH) is a relatively new technology utilizing 

fluorescently labeled DNA probes to detect or confirm gene or chromosome abnormalities 

that are generally beyond the resolution of routine Cytogenetics. The sample DNA (metaphase 

chromosomes or interphase nuclei) is first denatured, a process that separates the 

complimentary strands within the DNA double helix structure. The fluorescently labeled probe 

of interest is then added to the denatured sample mixture and hybridizes with the sample 

202

DNA at the target site as it reanneals (or reforms itself) back into a double helix. The probe 

signal can then be seen through a fluorescent microscope and the sample DNA scored for 

the presence or absence of the signal. This is one of the best and most straightforward 

methods available for the visual molecular analysis of the position of given gene sequences 

on chromosomes and there are evolutionary and taxonomic questions that can be addressed 

using this technique 

PCR ELISA (Enzyme-linked immuno-absorbent assay) 

Enzyme-Linked Immunosorbent Assay (ELISA) is 

a useful and powerful method in estimating ng/ml to 

pg/ml ordered materials in the solution, such as serum, 

urine and culture supernatant. It’s a kind of easy task 

to make ELISA if you have “good” antibodies against 

your concerned materials such as proteins, peptides 

and drugs. Entomological examples are pending, but 

a good example would be the screening of 

microorganisms in large population samples (Gibellini 

et al., 1993), e.g. in insect vectors of disease (Solano 

et al., 1995). It is a quick method of qualitative 

assessment of, e.g. races of insects in a collection, 

esterase-conferred insecticide resistance, etc, but it 

has yet to be utilized. The greatest single expense in 

using this technique would be for qualitativeassessment, 

i.e. a microplate reader. However, 

because of its PCR based assessment individual reaction costs would be high, but its speed and 

ability to screen large numbers of samples would be cost-effective It is an interesting new molecular 

technique which has potential for quick screening. 

Forensic Entomology : At a time when many aspects of forensic science are dominated 

by recent advances in the field of molecular biology, it is no surprise that DNA technology 

should also become a tool of the forensic entomologist. At present, efforts to develop these 

tools are still mostly at the research stage. However, they have the potential to move very 

quickly into widespread use by those who analyze insect evidence in forensic investigations. 

Since 1985, DNA typing of biological material has become one of the most powerful 

tools for personal identification in forensic medicine and in criminal investigation (Benecke, 

1997b). The advantages of using DNA are that it provides a huge amount of diagnostic 

information compared to some older techniques (such as blood-group typing), it is present 

in all biological tissues, and it is much more resistant to environmental degradation than 

most other biological molecules (e.g., proteins). 

APPLICATIONS OF MOLECULAR MARKERS IN ENTMOLOGY 

There are vast applications of molecular markers in Entomology. Some of the achievements 

made in this area have been listed in the following table along with the relevant references. 

For more details the reader may refer to the original papers. 

Remarks (Pros and Cons) about DNA Markers : 

Restriction fragment length polymorphisms (RFLPs): The main advantage, which is 

applicable to all DNA markers, is that the level of molecular variation detectable is increased. 

With RFLPs, this is because of numerous restriction enzymes that exist which cut the DNA 

at different sites and a diverse selection of probes based on hypervariable motifs. However, 

the main disadvantage is that such methods utilize radioactive probes (that are expensive 

and require specialized laboratories) which need to be screened from genomic libraries if 

203

APPLICATIONS OF MOLECULAR MARKERS IN ENTOMOLOGY 

204

not already available. Such screening can increase costs. Therefore, these markers are 

best adopted if probes from parallel studies to those contemplated already exist. 

DNA fingerprinting : The major disadvantage of DNA fingerprinting in general is that 

protocols outline the use of radioactive probes; however, such practices can be replaced by 

non-isotopic methods, but take time to adapt and problem-solving requires specialist advice. 

The cost of the system is similar to that for RFLPs, but synthetic probes negate the screening 

of genomic libraries. 

Microsatellites (simple sequence repeats; SSRs) : The advantage of this approach is 

the ability to detect greater levels of genetic variability (many microsatellite loci, often with 

numerous alleles (Evans, 1993), can potentially be screened for ecological use). Individual 

alleles can be scored at particular loci and provide good Mendelian markers. 

Randomly amplified polymorphic DNA (RAPDs) : This method is relatively quick (in 

comparison to radiolabel led work and sequencing), reveals great genetic variability due to 

the regions in which amplification takes place (Black et al.,1992), is useful in differentiating 

closely-related individuals and there are numerous commercially available primer kits (Operon 

Tech.) which can be used to screen populations. 

Conclusions : Long list of molecular markers, variable costs and efficiencies, specificity 

and non-specificity etc. are some of the features of molecular markers available in hand that 

make it easy for the user to decide the right choice of the marker system suited to his/her 

205

esearch goals. Biologists have now variety of choices among them. The available literature 

suggests that these DNA marker systems, as in plants, also show their worth in entomological 

areas. However, Entomologists need to modify the protocols (from plants to insects) to 

make full use of these systems and find out more areas of investigations. 

Important websites : 

http://pest.cabweb.org/PDF/BER/Ber88-6/Ber88577.pdf. 

http://www.ars.usda.gov/research/projects/projects.htm?ACCN_NO=405094&fy=2004 

http://www.nhm.ac.uk/hosted_sites/acarology/saas/saa/pdf07/003-014.pdf 

https://www.who.int/tdr/grants/workplans/entomol.htm 

http://www.scipub.net/botany/molecular-markers-plant-genetics-biotechnology.html 

http://www.scipub.net/entomology/index.html 

http://entomology.wisc.edu/~dshoemak/Publications/Pub.htm 



http://insects.ucr.edu/people/heraty.html 

http://www.ias.ac.in/currsci/feb252005/541.pdf 

http://www.colostate.edu/Depts/Entomology/courses/en575/en575.html 

http://www.mrcindia.org/mol-ent.htm 

http://www.ncbi.nlm.nih.gov/entrez 

query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10331278&dopt=Abstract 


Boulter D. (1993). Insect pest control by copying nature using genetic engineering crops. 

Phytochem. 34 : 1453-1466. 

Crickmore N., Ziegler D.R., FietelsonJ., Schnepf E., Van Rie J., Lerectus D., Baum 

J.and Dean D.H. (1998). Revision of nomenclature for Bacillus thuringiensis 

pesticidal crystal proteins. Microbiol. Mol. Biol. Rev. 62 : 807-813. 

Estruch J.J., Carrozzi N.B., Desai N., Duck N.B., Warren G.W. and Koziel (1997). Transgenic 

plants: An emerging approach to pest control. Nature Biotechnol. 15 : 137-141. 

Gatehouse A.M.R. and Gatehouse J.A. (1998) Identifying proteins with insecticidal activity: 

use of encoding genes to produce insect resistant transgenic plants. Pest. Sci. 

52 : 165-175. 

Hilder V.A. and Boulter, D.(1999). Genetic engineering of crop plants for insect resistancea 

critical review. Crop Protection 18 :177-191. 

Loxdale, H.D. and G. Lushai (1998) Molecular Markers in Entomology. Bulletin of 

Entomological Research (1998) 88, 577–600 

Ranjekar Ranjekar PK, Patankar A, Gupta VS, Bhatnagar RK, Bentur J and Ananda Kumar 

P (2003) Genetic engineering of crop plants for insect resistance. Current Science 

84 (3) : 321-329. 

Sharma H.C., Sharma K.K. and Crouch (2004). Genetic transformation of crops for insect 

resistance: Potential and limitations. Crit. Rev. Plant Sci. 23 (1) : 47-72. 

Vos P, Hogers R, Bleeker M, Reijans M, van de Lee T, Hornes M, Frijters A, Pot J, Peleman 

J, Kuiper M & Zabeau M (1995) AFLP: a new technique for DNA fingerprinting. Nucleic 

Acids Res. 23, 4407-4414. 

Williams JGK, Kubelic AR, Livak KJ, Rafalsky JA & Tingey SV (1990) DNA polymorphisms 

amplified by arbitrary primers are useful as genetic markers. Nucleic Acids Res. 

18, 6531-6535. 

206


LOSSES DUE TO INSECT-PESTS IN RABI VEGETABLES 

S. S. Sharma and V. S. Malik 



Fruit borer (Helicoverpa armigera) and whitefly (Bemisia tabaci) in tomato; leafhopper 

(Empoasca fabae), aphid (Myzus persicae), whitely (Bemisia tabaci), potato tuber moth 

(Gnorimoschema operculella) in potato; diamondback moth (Plutella xyllostella), aphid 

(Brevicorne brassicae), tobacco caterpillar (Spodoptera litura), leafwebber (Crocidolomia 

binnotata), headborer (Hellula undalis) and cabbage butterfly (Pieris brassicae) in cole crops; 

thrips (Thrips tabaci) and onion maggot [Hylemia=(Delia) antique] in onion and garlic; pod 

bores (Helicoverpa armigera and Etiella zinckella , blue butterfly (Polyomatous boeticus) 

and leaf miner(Chromatomyia horticola) in pea; black aphid (Aphis craccivora) in fenugreek; 

green aphid (Hyadaphis coriandri) and seed midge in coriander, fennel and cumin are among 

the most important pests of rabi vegetable crops. 

INSECT PESTS OF COLE CROPS 

Diamondback moth (Plutella xylostella) F : Yponomeutidae O : Lepidoptera 

Newly hatched larva enters the leaf tissues and feeds inside. Later on it comes out and 

feeds by scrapping the epidermis leaving behind typical white patches. Big caterpillar bites 

holes in leaves and may enter the flower also. If the young seedlings are attacked, the 

growing tip is eaten away and the curd is not formed. 

Economic Threshold : 20 larvae/plant (Prasad, 1963), 74 (3/4 instar) larvae/plant in 

seedling stage or 20 larvae/plant , 10 (3/4 instar) larvae/plant in one month after transplanted 

crop, or 20 (3/4 instar),larvae/plant in 1-2 months after transplanted crop (Jayarathnam, 

1977), 2 larvae/plant at 1-4 weeks after transplanting, or 5 larvae/plant at 5-10 WAT (Morallo 

el al., 1996) 

Loss : Viraktamath et al. (1994) reported a loss of 16.87-98.83 per cent. 

Tobacco caterpillar (Spodoptera litura (Fabricius) F : Noctuidae O : Lepidoptera 

The young larvae feed gregariously for few days on green material of leaf and skeletonize 

it and then disperse to feed individually. They feed on leaves by making big holes and enter 

the cabbage also. They are voracious feeders and faeces can be seen on leaves. 

Cabbage butterfly (Pieris brassicae (Linnaeus) F : Pieridae O : Lepidoptera 

The caterpillars feed gregariously during early stage and disperse as their reach maturity. 

The young larvae scrap the leaf surface whereas the old larvae eat up the leaves from the 

margin inwards leaving the main veins only. 

Loss : Thakur (1996) reported a loss of 68.5 per cent from Meghalaya 

Cabbage aphid : Lipaphis erysimi (KaItenback), Brevicoryne brassicae (Linnaeus) 

F : Aphididae O : Homoptera 

Both nymphs and adults suck cell sap from the plants especially the tender parts resulting 

in devitalization of the plants. They also produce honeydew, which attracts sooty moulds 

resulting in the hindrance in photosynthesis. 

207

Loss : A loss of 36.5 per cent in Uttar Pradesh (Ram et al. 1987) and 44- 54 per cent in 

Karnataka (Kumar et al., 1986) has been reported. 

Cabbage head borer (Hellula Undalis (Fabricius) F : Pyralididae O : Lepidoptera 

This is an important pest of cauliflower, cabbage, Chinese cabbage, and mustard cabbage. 

Major damage occurs on young plants but caterpillars also feed on older plants from 

transplanting and heading stage. Larva makes tunnel into the main stem resulting in stunting, 

deformed plants and multiple growing points or heads and sometimes death of young plants. 

Loss : A loss of 30 -58 per cent in Karnataka has been reported (Kumar et al. 1986). 

Leaf webber (Crocidolomia binotalis Zeller) F : Pyralidae O : Lepidoptera 

Males shows great delineation with dark tuft of hairs on the anterior margin of each 

forewing which the females lack. Larva dark heads and appear grey at hatching and light 

green thereafter with distinctive yellowish white stripes. One larva can finish the whole plant 

by feeding the growing point. Larva is highly mobile and reaches the preferred host plant. It 

also bores into cabbage head. 

Economic Threshold (E.T.) : 0.3 egg mass/plant (Sutiadi el al., 1994) 

Loss : A loss of 28.09.50.88 per cent in Karnatka has been reported (Peter et al., 1988). 

Sawfly (Athalia proxima (Klug) F : Tenthridinidae O : Hymenoptera 

Medium sized fly with black wings, larva is pseudo caterpillar black in colour damages 

the plant by cutting the leaf from margin. 

Loss: A loss of 36.5 per cent in Uttar Pradesh has been reported (Ram et al. 1987). 

INSECT PESTS OF TOMATO 

Fruit borer, Helicoverpa armigera (Hubner) F : Noctuidae O : Lepidoptera 

Nature of damage : Young larvae feed on tender leaves and advanced stage larvae feed 

on flower buds and fruits. Circular holes are made by the larva in fruits and it feeds the 

internal contents. A part of the body is kept outside the fruit. 

Economic Threshold (E.T.) : One larva per square meter area or one larva or one egg or 

one damaged fruit per plant. 8 eggs/15 plants or one larval/ plant (Sutiadi el al., 1994), 

Loss : A loss of 22.39 - 37.79 per cent in Karnataka has been reported (Tewari and 

Moorthy). 

Whitefly, Bemisia tabaci (Gennadius) F : Aleyrodidae O : Homoptera 

Nature of damage : Both nymphs and adults suck the cell sap from leaves and secrete 

honeydew on which attracts black sooty mold. They are vectors of virus diseases. 

EIL : 3 nymphs / leaf (Bolano, 1997). 

Leaf miner : Phytomyza atricornis F : Agromyzidae O : Diptera 

Nature of damage : The infested leaves show shiny white streaks against the green 

background due to which photosynthetic activity is reduced. 

208

INSECT PESTS OF PEA 

American bollworm (Helicoverpa armigera (Hubner) F : Noctuidae O : Lepidoptera 

Nature of damage : The larva makes a round hole on the pod and feeds the green 

grains in side the pod. While feeding, it keeps its head inside the pod and remaining body 

outside the pod. Sometimes whole larva goes inside the pod and all the grains are consumed. 

Leaf miner : Chromatomyia horticola Meigen F : Agromyzidae O : Diptera 

Eggs are laid in leaf tissue; maggots on hatching mine the leaves in zigzag fashion. 

Pupation takes place in the mines itself. Adults are tiny black files with transparent wings. 

The infested leaves show shiny white streaks against the green background due to which 

photosynthetic activity is reduced. 

Blue butterfly : Polyomatus boeticus (Linnaeus) F : Lycaenidae O : Lepidoptera 

Adult is small blue colured butterfly. Caterpillars are pinkish green, lethargic and feed 

on the internal contents of pod. 

Pod borers : Etiella zinckenella (Treitschke) F : Pyralidae O : Lepidoptera 

Adults are purple brown moths having greyish brown forewings. Caterpillars are reddish 

pink dorsally and pale green ventrally and feed inside the green pods on green grains. 

Fruit borer : Helicoverpa (=Heliothis) armigera (Hubner)F : Noctuidae O : Lepidoptera 

Young larvae feed on tender leaves and advanced stage larvae feed on flower buds and 

fruits. Circular holes are bored in fruits through which it thrusts its head inside the fruit and 

feeds the internal contents. Remaining part of the body keeps outside the fruit. 

Economic Threshold (E.T.) : One larva per square meter area or one larva or one egg or 

one damaged fruit per plant. 

Pea aphids (Acyrlhosiphon pisum (Harris) F : Aphididae O : Homoptera 

Both nymphs and adults suck the cell sap from the under side of the leaves. 

Economic Threshold (E.T.) : 3-4 aphids/stem tip (Bommarco, 1991), 

INSECT PESTS OF ROOT CROPS 

American bollworm (Helicoverpa armigera) in Radish F : Noctuidae O : Lepidoptera 

After hatching the young larva feeds on flower buds or pods. The anthers in the flower 

buds and the seeds in the pods are eaten. The pods become empty and hollow and there is 

heavy loss in seed production. 

Aphid in Radish, Raphanus sativus F : Aphididae O : Homoptera 

Both nymph and adults suck the cell sap from the leaves, stem and pods. The plant 

remains stunted and the pods shrivel resulting in week grain formation and heavy loss in 

seed producion. They secrete honeydew making the plant sticky. 

INSECT PESTS OF ONION AND GARLIC 

Onion thrips (Thrips tabaci Lindeman) F : Thripidae O : Thysanoptera 

The nymphs of this insect are tiny yellow wingless and the adults are brown black with 

fringed wings. Both the nymphs and adults can be seen moving fastly on the leaves and the 

209

central whirl of the plant. Both nymphs and adults lacerate the leaf tissues and suck the 

oozing out of the leaf tissues; silvery white blotches are formed which later on turn white 

brown; tip of the leaf dries up and plant remains stunted having twisted leaves ; the crop 

gives a burnt look. 

Onion maggot [Hylemya=(Delia) antique Meigen] F : O : Diptera 

The adult is a bristly, gray fly with large wings. The maggots are white legless larvae. 

After hatching the maggots crawl to the roots, stem and bulb and feed on them. The damaged 

plant becomes yellow to brown which later on dry away and the bulb may get rotten. 

INSECT PESTS OF FENUGREEK 

Black aphid (Aphis craccivora) F : Aphididae O : Homoptera 

This aphid is black, bold and shining in colour. They feed on leaves, mainly on stem, 

inflorescence and pods. The damaged pods shrivel and become week. The grains formed in 

the damaged pods are very thin and thus occurs a heavy loss in seed yield. 

Loss : A loss upto 62.3-68.8 per cent in Haryana has been reported (Sharma and Kalra, 

2002). 

INSECT PESTS OF CORIANDER 

Aphid (Hyadaphis coriandri) F : Aphididae O : Homoptera 

This aphid is pear shaped,light green in colour which looks like blue white. It is a serious 

pest at both vegetative and flowering stage. Both nymphs and adults suck the cell sap from 

leaves, stem and inflorescence. The damaged portion becomes sticky and the damage umbels 

look like burnt and production of seed in the damaged umbels is either zero or if formed they 

are very thin and of poor quality. 

Loss : Loss in seed yield may go up to 90 per cent (Kalra and Sharma 2006). 

INSECT PESTS OF CARROT SEED CROP 

Semilooper (Plusia orichalcea (Fabricius) F : Noctuidae O : Lpidoptera 

Moth has golden shiny fore wings, larva green in colour with light brown head feeds on 

the inflorescence of carrot seed crop. Flowers are heavily damaged leaving behind the flower 

petioles only. 

Loss : More than 90% in seed yield (Sharma, 2011). 


Jayarathnam, K. 1977. Studies on the population dynamics of the diamondback moth, Plutella 

xylostella (Lin.) (Lepidoptera:Yponomeutidae) and crop loss due to the pest in cabbage. 

Ph,D. Thesis, University of Agricultural Sciences, Bangalore 215 pp. 

Kalra, V. K., Sharma, S. S. and Tehlan, S. K. 2006. Population dynamics of Hyadaphis 

corianderi on different cultivars and varieties of coriander and seed yield losses caused 

by it. Journal of Medicinal and Aromatic Plant Sciences 28 : 377-378. 

Kalra, V. K.1992. Heliothis armigera Hubner on tomato- incidence and extent of damage- 

A note. Haryana J. Hort. Sci., 21 (3-4) : 316-318. 

210

Krishnaiah, K. 1980. Assessment of Crop Losses due to Pests and Diseases (Ed. H.C. 

Govindu). UAS Tech. Series. No. 33 : 259-267. 

Lange, W. H. and Bronson, L. 1981. Insect pests of tomato. Ann. Rev. Ent. 26 : 345-371. 

Peter, C., Iqbal, Sineh, Channa Basavanna, GP., Suman, C.L., Krishnaiah, K. and Singh, I. 

1988. Loss estimation in cabbage due to leaf webber Crocidolomia binotalis (Lepidoptera: 

Pyra1idae). Journal of the Bombay Natural History Society 85 : 642-644. 

Prasad, S.K. 1963. Quantitative estimation of damage to crucifers caused by cabbage worm, 

cabbage looper, diamondback moth and cabbage aphid. Indian Journal of Entomology. 

25 : 242-259. 

Sharma, S.S. 2011. Semilooper a serious pest of carrot seed crop. Annual Report 2011. 

Deptt.of Entomology, CCS HAU Hisar. 

Sharma, S. S. and Kalra, V. K. 2002. Assessment of seed yield losses caused by Aphis 

craccivora Koch, in fenugreek. Forage Res. 28 (3) : 183-184. 

Sutiadi, A. L., Prabaningrum, T. K., Mockaasan and Setiawati, W. 1994. Implementation of 

IPM Technology on Vegetables (Eds. A.A.Asandhi and S.Sastroviswoy’o) Lembang 

Horticultural Research Institute, Bendung, Indonesia pp. 14. 

Tewari, G. C. and Moorthy, P. N. K. 1994. Yield loss in tomato caused by fruit borer. Indian 

J. agric. Sci. 54 : 341-347. 

Trivedi, T.P., Rajagopal, D and Tandon, P.L 1994. Assessment of losses due to potato tuber 

moth. Journal of the Indian Potato Association 21 : 207-210. 

211

LIST OF PARTICIPANTS UNDER CAFT TRAINING 6 th to 26th SEPTEMBER, 2011 

Dr. S. Sivaramakrishnan 

Asstt. Professor 

Department of Biotechnology 

Bharathidasan University, 

Truchirappalli-620024 (Tamil Nadu). 

E-mail: sivaramakrishnan123@yahoo.com; Ph.09896269100 

Dr. Mohd.Ilyas Mohd.Osman, 

Asstt.Prof. (Entomology) 

Deptt. of Entomology, 

Marathwada Krishi Vidyapeeth, 

Parbhani-431402 (MS). 

E-mail: ilyas4080@gmail.com; Mob.: 09423901924 

Dr. Lalitkumar Vallabhdas Ghetiya 

Assistant Professor 

B.A. College of Agriculture, 

Anand Agril. University, 

Anand-388110 (Gujarat). 

E-mail: lvghetiya@yahoo.co.in; Mob: 09725006021 

Dr. Niraj Shriram Satpute, 

Assistant Professor, 


Dr. Punjabrao Deshmukh Krishi Vidyapeeth, 

Akola. 

E-mail: niraj_ento@yahoo.co.in; Mob: 09657725859. 

Dr. Shailendra Singh Dhaka 

Asstt. Professor 

KVK Pilibhit 

S.V. Patel University of Agri. & Tech.,Meerut. 

Mob: 09412114409; Email: chssdhaka@gmail.com 

Dr. Ravi Kumar Nehru 

Assoc. Professor 

Division of Entomology 

Sher-e-Kashmir Univ. of Agri. Sciences & Technology 

Kashmir, Shalimar, Srinagar-191121. 

E-mail: nehrurk@yahoo.co.in; Mob: 094191-03289 

Dr. Kalariya Girdharlal Bhagvanji 

Subject Matter Specialist (Plant Protection) 

Krishi Vigyan Kendra, 

Navasari Agricultural University, 

Navsari-396 450 (Gujarat). 

E-mail: girdharlalk@yahoo.com; Mob: 09925346796 

Dr. Balu Nilkanth Chaudhary 

Asstt. Prof. of Entomology 

Krishi Vigyan Kendra, Sindewani, Distt. Chanderpur (MS) 

212

Dr. Punjabrao Deshmukh Krishi Vidyapeeth, 

Akola. 

E-mail: bncent@rediffmail.com; Mob: 09404080566. 

Dr. Alpeshkumar V. Khanpara 

Asstt. Research Scientist 


COA, Junagarh Agril. University 

Junagadh-362 001 (Gujarat). 

E-mail: alpesh@jau.in; Mob: 09427736721 

Dr. Sambsiva Rao Nalla 

Scientist (Entomology) 

Post Harvest Technology Centre 

Acharya N.G. Ranga Agril. University 

Agriculture College Campus, Bapatla, Guntur Dt, 

AP-522101. Mob: 09959983680; 

Email: nallasambasivarao@gmail.com 

Dr. Bhamare Vijay Krishnarao 

Asstt. Professor (Entomology) 

COA Badnapur 

Marathwada Krishi Vidyapeeth 

Prabhani(M.S.). 

Email: bhamare@indiatimes.com; vijay.bhamare@rediffmail.com; Mob: 09822187248 

D. Nazrussalam 

Jr.Scientist-cum-Asstt.Professor, 

ZRS Darisai / BAU Ranchi 

Jharkhand. 

Mob: 09608725885 

Dr. Satya Pal Yadav 

Distt.Extension Specialist (Ento.) 

KVK, Fatehabad. 

Email: spkolana@gmail.com; Mob: 09466780600 

Mr. Nagendra Kumar 

Jr.Scientist-cum-Asstt.Prof. (Ento.) 

AICRP on MAP & BETELVINE, Deptt. of Plant Pathology 

Rajendra Agril. University, Pusa, Samastipur 

Bihar-848125. 

Email: nagendra_vamnicom@rediffmail.com; Mob: 09031536495 

Dr. Anjumoni Devee 

Asstt.Professor 


Assam Agril. University 

Jorhat (Assam) 

Email: amdevee@gmail.com; Mob: 09854192513 

Dr. Pravinkumar D. Ghoghari 

Assistant Research Scientist 

Agril. Experimental Station, Paria 

Navsari Agricultural University, Distt.Valsad 

Navsari-396 145 (Gujarat). 

Email: drpdg_29@rediffmail.com; Mob: 09428636583 

213

Dr. Tarun Verma, 

DES (Entomology) 

ATIC, CCS Haryana Agricultural University, 

Hisar. 

Email: vermatarun27@gmail.com; Mob: 09416929299 

Dr. Patel Snehalben Maganbhai 


Horticulture Polytechnic 

Aspee College of Horticulture & Forestry 

Navsari Agricultural University, Eru Char Rasta, Dandi Road 

Navsari-396 450 (Gujarat); Mob: 09428870528 

Dr. Sushil Kumar P. Saxena 

Associate Professor, Department of Plant Protection 

ASPEE College of Horticulture & Forestry 

Navasari Agricultural University, Eru Char Rasta, Dandi Road, Navsari-396 450 (Gujarat). 

E-mail: saxenasushil2003@rediffmail.com; Mob:09427108412 

Mr. Nimish Anil Kumar Bhatt 


B.A. College of Agriculture, 

Anand Agril. University 

Anand-388110 (Gujarat). 

Email: nabhatt@gmail.com; Mob: 09429328114 

Dr. Vijay Shankar Acharya 

Assistant Professor (Entomology) 

KVK, Beechwal, Bikaner 

SK Rajasthan Agril. University, Bikaner. 

E-mail: vijuzee@gmail.com; Mob: 09314477228 

Dr. T.Selvamuthukumaran 

Asstt. Professor (Entomology) 


Faculty of Agriculture, 

Annamalai University, Chennai (T.N.). 

Email: entoselva@gmail.com; Mob: 09443703124 

Dr. Suresh Kakroo, Assoc.Prof., 


Sher-e-Kashmir University of Agri. & Technology 

Kashmir, Shalimar-191121 (Srinagar). 

Email: suresh.kakroo@yahoo.in; Mob.: 09419149890. 

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Foreword - CCS HAU, Hisar

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