One of the most voracious pests of field crops in India is the pod-boring caterpillar, Helicoverpa armigera. This insect attacks a wide variety of plants, reproduces at an alarming rate of 1,000 per generation, and as an adult moth migrates huge distances. Scientists at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India have concentrated on this pest in their IPM research for several years.
Entomologist G. V. Ranga Rao led an effort to persuade Mr. Appaji to stop using pesticides on his groundnut crop for an entire season. The farmer was skeptical. But to his surprise, his unsprayed groundnuts yielded just as much as his neighbors' sprayed groundnuts. Moreover, he saved the money that he would have spent on pesticides.
When he stopped using pesticides, Appaji began exploring other pest control methods. He learned about the beneficial insects and parasites in his fields that fed on pests. He recognized the importance of birds who spread insect pathogens in their droppings and feed on insects and their larvae.
To attract birds to his groundnut fields, Appaji stuck small tree branches into the soil as perches. Because groundnut plants are close to the ground, birds cannot use them as vantage points for spotting insect prey. From a perch, however, birds can easily identify prey and swoop down to devour them.
Appaji's success inspired farmers in his village and the neighboring village to adopt his techniques. In the following growing season, 400 hectares of groundnuts were grown without pesticides. Farmers also erected bird perches in their fields.
The farmers who adopted the non-chemical control had higher yields than those who used chemicals. Collectively, they also saved 1 million rupees. Formerly, they each had spent 2,500 rupees (US$86) on pesticides for each acre of land. The innovations and experimentation of one farmer allowed many farmers to save money.
Now those same farmers are working in conjunction with ICRISAT to screen several high-yielding, pest-resistant groundnut varieties developed by ICRISAT.
Another main crop grown in the region, cotton, is especially susceptible to pest damage. ICRISAT scientists M.V. Potdar and Merle Anders have set up two intercropping systems; cotton/pigeonpea and cotton/sorghum. They are growing both combinations with and without pesticides. So far, they have found larger numbers of pod-borers on sprayed crops. There is no difference in yield between the sprayed and unsprayed plots.
Many ICRISAT entomologists are convinced that insecticides are not the answer in the fight against Helicoverpa. If farmers and scientists share their knowledge and experience regarding the pod-borer, they may finally develop sustainable pest management systems to control the pod-borer and other pests.
G.V. Ranga Rao
Andhra Pradesh 502 324