Integrating biopesticides in pest management strategies for tropical vegetable production

Vegetables, cultivated on 4.65 million ha with annual production of 53.5 million t in South and Southeast Asia, are subject to severe yield losses from insect pests and diseases in the tropics. Chemical pesticides account for onethird to one-half of the total mean material input cost for vegetable production in the region. Extensive and inappropriate pesticide use has led to pests developing resistance to major groups of pesticides, resurgence of secondary pests, high pesticide residues in produce, and decimation of natural enemies. The adverse effects on human and environmental health cannot be ignored. Integrated pest management (IPM) strategies often have been suggested to mitigate such a problem. Although various IPM strategies have been developed and promoted for vegetables, adoption remains low due to IPM’s limited effectiveness in managing insect pests compared with chemical pesticides. Moreover, IPM has been promoted as a combination of techniques without giving due consideration to the compatibility of each component. Biopesticides could play a crucial role in IPM strategies although they cover only about 4 percent of the global pesticide market. Biopesticides have high compatibility with other pest management techniques such as natural enemies, resistant varieties, etc. Integrating biopesticide could enhance performance of IPM strategies. For instance, with the adoption of Bacillus thuringiensis based biopesticides, parasitoids such as Diadegma semiclausum, Cotesia plutellae and Diadromus collaris established in several countries, and provided significant control of diamondback moth (Plutella xylostella) on brassicas in Southand Southeast Asia. An IPM strategy based on sex pheromone for managing the eggplant fruit and shoot borer (Leucinodes orbonalis) has reduced pesticide abuse and enhanced the activities of natural enemies including Trathala flavoorbitalis in Indo-Gangetic plains of South Asia. Thus, this paper reviews some of the most effective vegetable IPM strategies developed and/or promoted by AVRDC – The World Vegetable Center to manage insect pests on brassicas, eggplant, vegetable legumes and tomato in tropical Asia, and presents a discussion of an appropriate public – private partnership model in dissemination and adoption of vegetable IPM strategies.