Biological Control in India

Natural enemies of crop pests are mainly responsible for checking the population build up of the crop pests in the nature. However, in the past five decades indiscriminate use of pesticides has altered the natural balance resulting in frequent pest outbreaks and minor pests attaining major status in many crop ecosystems. Recent outbreaks include citrus black fly Aleurocanfhus woglumi Ashby, cotton whitefly Bemisia tabaci (Gennadius), sugarcane Pyrilla Pyrillaperpusilla (Walker) and cotton boll worm Helicoverpa armigera (Hubner). Some of the pests such as rice leaf folder Cnaphalocrocis medinalis (Guenee), green leafhopper Nephotettix spp., white blacked plant hopper Sogatellafurcifera (Horvath) in rice ecosystem and old world boll worm Helicoverpa armigera (Hubner) in cotton have become serious pests which were once of no economic importance. Indiscriminate use of pesticides has resulted in development of resistance to many pesticides in H. armigera, Nilaparvata lugens (Stal.), Plutella xylostella (Linn.), Liriomyza trifolii (Burgess), etc.

Five million tonnes of pesticide is applied in agriculture all over the world. Inspite of this, pests around the globe destroy about 35 per cent of all potential crops before harvest. Such scenario indicates that use of pesticides has been only marginally successful at improving agricultural productivity. In India, annual loss caused by the crop pests and weeds is estimated to be Rs.200 billions. This situation has lead to a growing realisation to adopt alternative methods of pest suppression to protect our habitat, conserve our natural resources and utilise sustainable methods of pest management. In past decade or so new approaches in biological control research has lead to identification of superior strain of Trichogramma chilonis Ishii for use in cotton, sugarcane and tomato ecosystem. This has resulted in better suppression of the crop pests. Efforts made have also resulted in developing natural enemies release schedule for biosuppression of sugarcane borers, scale insects and Pyrilla; coconut black headed caterpillar and rhinoceros beetle; maize stem borer and many fruit crop pests. Biointensive integrated pest management (BIPM) has been developed for pests of tobacco, rice, cotton and vegetables. BIPM technology on these crops has resulted in reduction of pesticide usage considerably and better cost benefit ratio. Efforts are being made now to utilise nematophagous fungi and bacteria for suppression of plant parasitic nematodes and use of fungal and bacterial antagonists for suppression of plant diseases especially in crops like sunflower, groundnut, cotton, rice, wheat and potato. The advances made in biological control of crop pests, diseases and weeds are presented in this paper.