Nucleotide polymorphism and modulation of carboxyl esterase activity in Spodoptera litura (F.) (Noctuidae: Lepidoptera)

Tobacco caterpillar, Spodoptera litura (F.) is one of the lepidopteran pests which has developed resistance to organophosphate and synthetic pyrethroid insecticides. Development of resistance is mainly underlined by elevated level of carboxylesterase (CarE). In this study, S. litura strains obtained from cauliflower growing region were examined for enzyme, CarE level. Elevated level of CarE was observed in Sonepat strain (28.09 ± 0.09 μmol/min) followed by Delhi (26.72 ± 0.04 μmol/min) and Varanasi strain (10.00 ± 0.44 μmol/min). The gene encoding CarE enzyme was partially characterized (497bp). Sequence data revealed polymorphism at nucleotide level and gene was identical in all the three strains and similar to that of other species such as S. exigua as well as S. littoralis. Polymorphism at the nucleotide level could be attributed to differential activity of CarE.