Insecticide Resistance Development and Detoxification Enzyme Activities of Spodoptera litura (Fabricius) in Soybean from Kumaon Himalayas

Background: Soybean is an important crop of Uttarakhand both in hills as well as in plains and Spodoptera litura is an important pest of soybean in Uttarakhand. Several insecticides have been in use for its management and resistance has been observed against different group of insecticides. Thus, to study the level of infestation and insecticide resistance from soybean fields of hill farmers of Kumaon Himalaya, survey and experiments were conducted. Methods: Survey was conducted and scale of infestation was determined. Chemical and biochemical assay were conducted to study insecticide resistance. For chemical assay IRAC Method No. 7 using insecticides indoxacarb 14.5% SC, chlorantraniliprole 18.5% Sc, fipronil 5% SC, chlorpyriphos 50%+cypermethrin 5% EC and profenofos 40%+cypermethrin 4% EC and for biochemical assay the specific activity of Carboxylesterase, Acetyl choline esterase, Mono-oxygenase and Glutathione-S-transferase was studied. Result: The infestation level from different regions showed the presence of S. litura, ranging from mild to severe infestation. The resistance ratio of different insecticides used ranged from a low to an extremely high resistance level with LC50 ranging from 0.37 µg/ml to 1648.84 µg/ml. The biochemical analysis of carboxylesterase, acetylcholinesterase, monooxygenase and gluthione-s-transferase showed an overproduction of these detoxification enzymes in the resistant population.