Resistance in Spodoptera litura (F.) to Insecticides and Detoxification Enzymes

Standard leaf dip bioassay experiments were conducted to study the insecticide resistance in Spodoptera litura (F.) in soybean. Chlorantraniliprole was the most toxic while, cypermethrin and organophosphates (profenophos and triazophos) recorded least toxicity against S. litura populations. Field population of S. litura showed the highest resistance to cypermethrin with resistance ratios (RRs) ranging from 244 to 376. The field populations collected from three locations of Southern Rajasthan exhibited low resistance to newer insecticides, chlorantraniliprole and spinetoram with Lab-SS strain. All the enzyme activities were significantly higher in the whole larval extracts and midgut extracts of S. litura larvae when compared to the Lab-SS strain. Analysis of the carboxyl esterase enzyme in the native PAGE assay revealed that the electrophoretic profiles showed presence of different band regions (EST 1 to EST 7) with esterase activity in the field populations along with the laboratory susceptible strain. The susceptibility of three field populations to different group of insecticides along with the profile of detoxification enzymes indicate the need to formulate a region-specific insecticide resistance management (IRM).