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.