Whitefly and whitefly-borne viruses in the tropics : Building a ... - cgiar

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Cameroon Farmers undertook various measures to combat the whitefly/CMD problem. The common practices were roguing, choice of resistant varieties, selection of planting material and the application of wood ash or of fertilizers (Figure 4). Less than 2% of farmers used pesticides against whiteflies and/ or CMD. Even though it might be supposed that the high incidence of cutting infection observed in the survey would make roguing an unattractive strategy, it was nevertheless the predominant practice. Roguing Varieties Selection Fertilizers Wood ash Pesticides 0 5 10 15 20 25 30 35 Relative frequency (%) of practice Figure 4. Cassava mosaic disease management practices used by farmers in Cameroon. In their choice of varieties, 86% of the farmers were aware of the differences in susceptibility to the disease among cassava varieties. Among improved varieties recommended for their disease resistance, “Agric” (of International Institute of Tropical Agriculture, Nigeria [IITA] origin), chosen by 47% of farmers, was the most commonly selected. The variety Pawpaw leaf was the single most frequently planted CMD-resistant local variety (chosen by 9% of farmers). Other CMD-resistant local varieties cited were Metta agric, Mfont and Ndongo. Most farmers (96%) indicated that in selecting planting materials they intentionally chose parent plants with minimal or without CMD symptoms. This practice would inherently favour CMD-resistant varieties. Farmer-led rapid multiplication schemes to produce CMD-resistant varieties may therefore be relatively easy to promote under such circumstances by building upon previous technology transfer experiences and farmer training programmes in the country (Dahniya et al., 1994; Akoroda, 1997; Bakia et al., 1999). In selecting planting material, the five most important criteria were yield (34.3% of farmers), followed by stem health (25.7% of farmers), absence of diseases (17.1% of farmers), stem size (5.7%) and stem maturity (4.3%). Most farmers expressed willingness to change planting dates for CMD control but 30% of them indicated unwillingness to alter planting date. Conclusions There was only limited evidence of CMD being spread by its whitefly vector in farmers’ fields in Cameroon. Infected planting material was the major source of CMD and a major extension effort will be required to encourage farmers to select diseasefree and healthy planting materials. If effective measures to improve crop health are to be developed, the importance of latent infection will have to be investigated. The expressed willingness of farmers to alter planting dates and their conviction that CMD incidence varies with climatic conditions paves the way for participatory action research to optimize times of planting in the various ecozones so as to reduce CMD incidence and damage. In such studies, it may be useful to monitor the population dynamics of B. tabaci to see whether its abundance varies at the different planting times. Evaluation of parasitism by existing natural enemies (E. sophia, for example) may help show whether biological control 43
contributes significantly to regulating populations of the vector. Such information will contribute to understanding the role of B. tabaci in the epidemiology of CMD. Even though the CMD damage observed in the survey was slight, farmers provided high yield loss estimates. This suggests the need for farmer participatory yield loss trials to quantify losses both of storage roots and leaves, especially since the latter are widely consumed as leafy vegetables, but losses have been little studied. Farmer participatory varietal selection trials also need to be conducted on the local cassava varieties (such as Pawpaw leaf ), which farmers report to be CMD-resistant, and comparisons made with cultivars whose response to CMD is well documented. Such studies will provide valuable input into breeding programmes that aim to achieve sustainable high yields in varieties preferred by farmers and to increase adoption of such varieties. 44 References Akoroda, M. O. 1997. Cassava technology transfer: Lessons from Cameroon and Nigeria. Afr. J. Root Tuber Crops 2:257-260. Bakia, B.; Ambe, J. T.; James, B. 1999. Technology transfer strategies: The case of sustainable cassava plant protection in Cameroon. Afr. J. Root Tuber Crops 3(2):23-27. Dahniya, M. T.; Akoroda, M. O.; Alvarez, M. N.; Kaindaneh, P. M.; Ambe- Tumanteh, J.; Okeke, J. E.; Jalloh, A. 1994. Development and dissemination of appropriate root crops packages to farmers in Africa. In: Ofori, F.; Hahn, S. K. (eds.). Tropical root crops in a developing economy. Procs. Ninth Symposium of the International Society for Tropical Root Crops (ISTRC), 20-26 October 1991, Accra, GH. p. 2-9. Whiteflies and Whitefly-borne Viruses in the Tropics Fargette, D.; Thresh, J. M. 1994. The ecology of African cassava mosaic geminivirus. In: Blakeman, J.P.; Williamson, B. (eds.). Ecology of plant pathogens. CAB International, Wallingford, GB. p. 269-282. Fauquet, C.; Fargette, D. 1990. African cassava mosaic virus: Etiology, epidemiology and control. Plant Dis. 74:404-411. Fishpool, L. D. C.; Burban, C. 1994. Bemisia tabaci: The whitefly vector of African cassava mosaic geminivirus. Trop. Sci. 34:55-72. Fondong, V. N.; Adipala, A.; Thresh, J. M. 1997. Spread of African cassava geminivirus at four agroecological locations of Cameroon. Afr. Crop Sci. J. 3:1035-1049. Geddes, A. M. 1990. The relative importance of crop pests in sub- Saharan Africa. Bulletin no. 36, Natural Resources Institute (NRI), Chatham, GB. Gregory, P. H. 1948. The multiple infection transformation. Ann. Appl. Biol. 35:412-417. James, B. D.; Legg, J. P.; Gbaguidi, J. B.; Annang, D.; Asiabaka, C. C.; Cudjoe, A. R.; Echendu, T. N. C.; Maroya, N. G.; Ntonifor, N.; Ogbe, F.; Salawu, R. A.; Tumanteh J. A. 1988. Understanding farm-level epidemiology of cassava mosaic disease. In: Abstracts, 7th Triennial Symposium of the International Society for Tropical Root Crops- Africa Branch (ISTRC-AB), 11-17 October 1988, Cotonou, BJ. p. 122. Legg, J. P. 1995. The ecology of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), vector of African cassava mosaic geminivirus in Uganda. Ph.D. thesis, University of Reading, GB.
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About the Partners CIAT The Interna
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Centro Internacional de Agricultura
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Chapter 4 Whiteflies and Whitefly-b
Page 8 and 9: Chapter 6 Whiteflies and Whitefly-b
Page 10 and 11: Contents Page Foreword vii Introduc
Page 12 and 13: Contents Chapter SECTION THREE Whit
Page 14 and 15: Foreword This book is the product o
Page 16 and 17: Introduction Introduction The Probl
Page 18 and 19: Introduction In addition to the yie
Page 20 and 21: Introduction in pesticide use in La
Page 22 and 23: Introduction annual crops, especial
Page 24 and 25: Introduction Plant Resistance contr
Page 26 and 27: Introduction Otim-Nape, G. W.; Bua,
Page 28 and 29: SECTION ONE Whiteflies as Vectors o
Page 30 and 31: Introduction CHAPTER 1.1 Introducti
Page 32 and 33: Introduction diseases than is cassa
Page 34 and 35: Introduction Sub-project on Whitefl
Page 36 and 37: Introduction References Aritua, V.;
Page 38 and 39: Introduction Thresh, J. M.; Otim-Na
Page 40 and 41: Ghana 1997, on 80 farms. These incl
Page 42 and 43: Ghana (6.2%), Bakentenma (5%) and K
Page 44 and 45: Ghana Legg, J. P.; James, B. D. 199
Page 46 and 47: Benin Northern guinea savannah Sout
Page 48 and 49: Benin or disease problem, the main
Page 50 and 51: Nigeria CHAPTER 1.4 Nigeria Introdu
Page 52 and 53: Nigeria TMS 30572 (18.8%) and TMS 3
Page 54 and 55: Nigeria FAO (Food and Agriculture O
Page 56 and 57: Cameroon protocol, to enable valid
Page 60 and 61: Cameroon Robertson, I. A. D. 1987.
Page 62 and 63: Uganda between November 1997 and Ja
Page 64 and 65: Uganda environment, host plant heal
Page 66 and 67: Uganda local varieties. Assessments
Page 68 and 69: Uganda Harrison, B. D. 1987. Proper
Page 70 and 71: Kenya Recent epidemiological studie
Page 72 and 73: Kenya respective diseases were reco
Page 74 and 75: Kenya Bock, K. R. 1983. Epidemiolog
Page 76 and 77: Tanzania CHAPTER 1.8 Tanzania Intro
Page 78 and 79: Tanzania Adult whiteflies were more
Page 80 and 81: Tanzania loss) to assess yield loss
Page 82 and 83: Tanzania Legg, J. P.; Raya, M. 1998
Page 84 and 85: Malawi Increased Biological Underst
Page 86 and 87: Malawi Physiology and Ecology in th
Page 88 and 89: Madagascar Tanzania Madagascar Moza
Page 90 and 91: Madagascar surprising, particularly
Page 92 and 93: Diversity of African Cassava Mosaic
Page 98 and 99: Sweetpotato Virus Disease in East A
Page 104 and 105: Factors Associated with Damage CHAP
Page 106 and 107: Factors Associated with Damage Mean
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Factors Associated with Damage % SP
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Factors Associated with Damage thro
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Factors Associated with Damage Gedd
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Conclusions and Recommendations col
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Conclusions and Recommendations Mal
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Conclusions and Recommendations Mpi
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Conclusions and Recommendations com
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Conclusions and Recommendations con
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Conclusions and Recommendations (2)
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Conclusions and Recommendations Ger
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SECTION TWO Whiteflies as Pests and
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Introduction CHAPTER 2.1 Introducti
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Introduction Czosnek, H.; Navot, N.
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Sudan cotton, leading to the introd
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Sudan Table 1. Reproductive host pl
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Sudan Historically, Sudan has been
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Sudan Only 10% of producers reporte
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Sudan Conclusions The work conducte
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Kenya CHAPTER 2.3 Kenya Introductio
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Kenya Increased Biological Understa
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Kenya Samples of 10 plants per fiel
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Kenya Table 4. Maximum incidence (%
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Kenya Seventy-nine percent of tomat
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Kenya under Phase 2 of the TWF-IPM
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Tanzania CHAPTER 2.4 Tanzania Intro
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Tanzania The reproductive host plan
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Tanzania Geographical range of whit
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Tanzania Local names given to white
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Tanzania Nono-Womdim, R.; Swai, I.
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Malawi levels of infestation by the
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Malawi Table 3. Maximum incidence (
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Malawi (40%) believe that the white
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Tomato Yellow Leaf Curl Virus in E.
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Conclusions and Recommendations CHA
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Conclusions and Recommendations (Fi
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Conclusions and Recommendations Cen
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Conclusions and Recommendations the
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SECTION THREE Whiteflies as Vectors
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Introduction especially for export.
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Mexico CHAPTER 3.2 Mexico Introduct
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Mexico Culiacán, Sinaloa, in north
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Mexico Table 2. Virus survey of tom
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Mexico results of the molecular bio
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Mexico Strengthened Research Capaci
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Mexico López, R. 1996. Experiencia
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Guatemala 1960s, and at this time t
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Guatemala Table 2. Results of white
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Guatemala Table 5. Cropping systems
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Guatemala contemplated in this prel
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El Salvador CHAPTER 3.4 El Salvador
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El Salvador During the course of th
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El Salvador markets: common bean, m
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El Salvador Current Status of White
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Honduras Copan Ocotepeque Santa Bá
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Honduras Table 3. Biotyping of whit
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Honduras References Caballero, R. 1
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Nicaragua Nueva Segovia Madriz Este
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Nicaragua Lowlands of Nicaragua. Th
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Nicaragua Region VI is a main horti
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Costa Rica CHAPTER 3.7 Costa Rica I
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Costa Rica Table 1. Characterizatio
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Costa Rica Castillo, J. 1997. Movim
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Panama Bocas del Toro Chiriquí Ver
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Panama Gámez, R. 1970. Los virus d
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Haiti Grande-Anse Sud Grande-Anse S
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Haiti collaborators in this project
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Cuba Ciudad de la Habana Pinar del
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Cuba Table 3. Comparative homologie
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Cuba project provided three keynote
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Dominican Republic CHAPTER 3.11 Dom
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Dominican Republic monoclonal antib
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Dominican Republic Strengthened Res
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Reproductive Crop Hosts of Bemisia
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Biotypes of Bemisia tabaci CHAPTER
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Biotypes of Bemisia tabaci For this
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Biotypes of Bemisia tabaci 100 99 B
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Biotypes of Bemisia tabaci biotype
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Biotypes of Bemisia tabaci Table 2.
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Biotypes of Bemisia tabaci Already
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Conclusions and Recommendations gre
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SECTION FOUR Whiteflies as Pests of
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Introduction control, due to resist
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Introduction Posada, L. 1976. Lista
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Colombia and Ecuador B biotype B. t
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Colombia and Ecuador assistants and
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Colombia and Ecuador and squash. On
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Colombia and Ecuador Table 2. Main
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Colombia and Ecuador Table 6. Patte
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Insecticide Resistance in Colombia
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Conclusions and Recommendations res
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Conclusions and Recommendations rot
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SECTION FIVE Special Topics on Pest
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Sustainable IPM through Host Plant
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Page 328 and 329:
Biological Control of Whiteflies by
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Progress of Cassava Mosaic Disease
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Management of the Cassava Mosaic Di
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Conclusions Conclusions The Tropica
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Conclusions whitefly pests and thus
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Conclusions developing countries, a
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Acronyms and Abbreviations Acronyms
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Acronyms and Abbreviations FIRA Fid
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Acronyms and Abbreviations PROFRIJO
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Acronyms and Abbreviations PYR pyre
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Whitefly and whitefly-borne viruses in the tropics : Building a ... - cgiar

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