PEST RISK ANALYSIS (PRA) TRAINING Group Exercises Manual

APPENDIX 8
PEST RISK ANALYSIS TRAINING - GROUP EXERCISES MANUAL
Thrips (Thysanoptera) species associated with mango trees in South Africa
T. Grové 1 , J.H. Giliomee 2 & K.L. Pringle 2
1 ARC - Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspruit, 1200 South Africa
2 University of Stellenbosch, Private Bag X1, Matieland, 7602 South Africa
INTRODUCTION
Thrips (Thysanoptera) were collected on mango trees (Mangifera indica L. (Anacardiaceae))
from 1992-1996 in the main mango production areas in South Africa to identify the complex
of species associated with this crop and to monitor their abundance. Different monitoring
techniques were used, which included sampling of flowers, fruit and leaves and the use of
both yellow card and dispersal/emergence trapping methods. Fifteen thrips species were
recorded, eleven belonging to the family Thripidae and four to the family Phlaeothripidae. The
citrus thrips, Scirtothrips aurantii Faure, and the red-banded thrips, Selenothrips rubrocinctus
(Giard), were the only two species that caused lesions on the fruit. Numbers of S. rubrocinctus
were usually low in mango orchards and did not seem to be of economic importance. By
contrast, Scirtothrips aurantii was abundant on new growth, causing stunting of growth and
leaf malformation. Aleurodothrips fasciapennis (Franklin) and Haplothrips bedfordi Jacot-
Guillarmod were the only predatory thrips recorded. The western flower thrips, Frankliniella
occidentalis (Pergande), was collected from mango flowers in the Letsitele area, while Thrips
acaciae Trybom, Thrips tenellus Trybom and S. aurantii were the most abundant species in
the flowers.
Key words: Thysanoptera, Mangifera indica, Scirtothrips aurantii, Selenothrips rubrocinctus,
mango, thrips.
Different species of Thysanoptera vary greatly
in their habits. Most feed, using their piercing and
sucking mouthparts, on either flowers and leaves
of green plants, or fungi, while some are predatory
and a few feed on mosses and detritus (Lewis
1997b). Flowers are particularly favoured by
many species (Kirk 1984, 1987). Thrips can
damage crops directly by feeding or indirectly by
virus transmission (Ullman et al. 1997). Predatory
thrips can be useful as natural biocontrol agents,
feeding on pest insects and mites, and thrips in
flowers can be useful as pollinators by increasing
crop yield (Kirk 1997).
Several thrips species are known to attack
cultivated mangoes (Mangifera indica L. (Anacardiaceae))
worldwide. The greenhouse thrips,
Heliothrips haemorrhoidalis (Bouché), is a
cosmopolitan species which is known to occur on
this crop in Israel (Wysoki et al. 1993). The red
banded or cacao thrips, Selenothrips rubrocinctus
(Giard), is also a cosmopolitan species that attacks
mango in several countries (Hill 1975; Lewis
1997a). Both H. haemorrhoidalis and S.
rubrocinctus are sporadic, but potentially serious,
pests on avocado fruit in South Africa (Dennill &
Erasmus 1992). Scirtothrips rubrocinctus usually
damages young mango trees and trees in
nurseries, but rarely mature trees (Hill 1975). The
extent of damage caused by these two species to
mango in South Africa is not known.
The South African citrus thrips, Scirtothrips
aurantii Faure, has been known to severely scar
young mango fruit (Annecke & Moran 1982). The
chilli thrips, Scirtothrips dorsalis Hood, and the
grapevine thrips, Rhipiphorothrips cruentatus
Hood, occur on mango in South Asia and cause
leaf damage (Lewis 1997a). Scirtothrips dorsalis
has been recorded from the castor oil plant,
Ricinus commnunis L., in South Africa (Gilbert
1986), but has not yet been recorded as a crop pest
in South Africa. The Mediterranean mango thrips,
Scirtothrips mangiferae Priesner, attacks mango
in Egypt and Israel (Mound & Palmer 1981;
Venezian & Ben-Dov 1982; Wysoki et al. 1993).
This species can be a severe pest on mainly young
trees, causing the young leaves to curl and drop
prematurely. Twigs of infested shoots are much
shorter than those of uninfested ones. The western
flower thrips, Frankliniella occidentalis
(Pergande), is an economically important pest of
mango in Israel and causes serious damage
consisting of skin silvering and heavy skin
African Entomology 9(2): 153-162 (2001)
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