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No early indications of attack (puncturing and sap-sucking) by M. usitatus are apparent. Injury to plant tissues due to oviposition easily escapes the naked eye. After a week or so, young leaves and flowers begin to wilt. Wilting is caused by the feeding of both adults and nymphs.
Grout and Richards (1990) (in Chang, 1990) indicated that yellow PVC cards coated with a sticky pesticide have been used by farmers to monitor and control the citrus thrips, Scirtothrips aurantii in South Africa. This method may be feasible for M. usitatus which was found to be most attracted to blue-coloured water-pan traps during movement from adzuki beans to other leguminous crops. The efficiency of blue sticky traps to control M. usitatus has been tested. Blue traps caught significantly more M. usitatus than yellow or green traps during the winter crop. In spring, the order of preference of M. usitatus was blue > white > yellow > green. However, when the population increased there was no difference in the number of thrips being attracted to blue and white traps (Chang, 1990b).
Three eulophid parasitoids of M. usitatus have been reported. The most recent is Ceranisus menes. However, studies on its bionomics and potential as biological control agent against M. usitatus are still needed (Chang, 1991).
Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources:
M. usitatus is the most common species of Megalurothrips in the Oriental region but nowhere has it ever reached such pest populations as M. sjostedti (Palmer, 1985).
Miyasaki et al. (1984) record M. usitatus on mung beans and groundnuts and as most abundant on soyabeans in Java but crop yield is not significantly affected.
In Taiwan the yield loss in groundnuts caused by M. usitatus and other thrips species has been estimated to be about 30%. Yield losses in soyabeans, adzuki beans and other legumes due to infestation of M. usitatus alone has not been assessed (Chang, 1988c).