It has become a common practice to use synthetic chemicals to control insect pests. Pesticides are harmful to environment, non‐target living organisms and human beings. In the recent past, biopesticides obtained from plant or microbial sources are gaining importance as alternative to chemical pesticides. One of the well known microorganisms having pesticidal activities is Bacillus thuringiensis (B.t), a gram positive bacterium that produces a crystal protein, selectively toxic to the caterpillar type of pests. Besides B.t, a broad spectrum biopesticide from actinomycetes sp. is being used as biopesticide to control the agriculturally important pests.
B.thuringiensis, a native isolate obtained from rice field soil, was found to control a number of pests viz., Cnaphalocrocis medinalis (rice leaf folder), polyphagous pests like Helicoverpa armigera, Spodoptera litura and Amanranthus leaf feeder in the laboratory assays.
It was observed from a small scale field trial in a farmer's field that the wettable powder formulation of B.t, a liquid formulation of Spinosyn (a pesticidal compound obtained from Streptomyces parvulus) and a combination of both biopesticides controlled the caterpillar type of pests in vegetable and paddy crops. With prevailing need of biopesticides in Tamil Nadu and elsewhere, the use of B.t based biopesticide will be promoted among farmers after extensive large scale field testing.
