author(s)
V Karuppaiah, Chitra Srivastava and S Subramanian

abstract
Three field populations of Tobacco caterpillar, Spodoptera litura were tested for their susceptibility to newer chemistry insecticides and conventional mixtures. Third instars larvae of F1 generation of field population were deployed in a bio-assay using the topical application method. The index of effectiveness, security index (SI) of insecticides was worked out by comparing of dose response with established field use rates. Bio-assay results revealed that, chlorantraniliprole 18.5% SC @ dose ranging from 1-4 ppm (LC50) and emamectin benzoate 5% SG @ dose of 1-3ppm (LC50) were most effective formulations for all three field populations of S. litura. While, conventional insecticides mixtures, koranda (chlorpyrifos 50% + cypermethrin 5%) and polytrin C (profenofos 40%+ cypermethrin 4%) were less effective for all three populations. Security index (SI) indicates that insecticides, emamectin benzoate, chlorantraniliprole, indoxacarb, bifenthrin, and pyridalyl are likely to be completely effective formulations to all three field populations with SI value of ≥ 1, except in some case. The pairwise correlation coefficient of LC50 values indicated that cross interaction within the insecticides was not significant except amid group insecticides (flubendiamide and chlorantraniliprole) that had positive correlation with a pyrethroid and a pyrethroid plus OP mixture. Of these tested, chlorantraniliprole and emamectin benzoate would be better chemical to manage S. litura irrespective of locations/populations. At recommended field dose, both of these insecticides scored the security index (SI) threshold value ≥1 for all populations and they could be considered effective insecticides for the management of S. litura.