Insecticide Resistance, Biological Traits and Enzyme-mediated Detoxification in Rice Brown Planthopper (Nilaparvata lugens) Populations from the Kampasagar Region

Field-collected populations of Nilaparvata lugens from Kampasagar were evaluated for insecticide resistance, detoxification enzyme activity, and biological parameters in comparison with a long-term susceptible glasshouse BPH colony. Toxicity assays were conducted using the rice plant spray method against commonly used insecticides, and detoxification enzyme activities (esterases, glutathione S-transferases, and cytochrome P450 monooxygenases) were quantified using standard protocols. Biological studies were carried out by rearing insects on TN1 seedlings to record development and reproductive parameters. The field populations exhibited very high resistance to neonicotinoids (imidacloprid, thiamethoxam, ethiprole + imidacloprid) and buprofezin (RR up to 1740.5), moderate resistance to chlorpyriphos, and low resistance to acephate, dinotefuran, fipronil, and pymetrozine. Enzyme assays showed elevated esterase (1.8-fold), GST (1.5-fold), and cytochrome P450 monooxygenase (3.7-fold) activities compared to the susceptible strain. Resistant populations recorded longer egg and pre-oviposition periods, prolonged nymphal duration (13–14 days), reduced nymphal survival (77.2–90.9%), lower egg hatchability (79.1–90.9%), reduced fecundity, a lower proportion of females, and longer total life cycle. Five nymphal instars were observed, and incubation period ranged from 6–8 days, consistent with earlier standardized observations.