Biochemical resistance mechanisms against chlorpyrifos, imidacloprid and lambda-cyhalothrin in Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

Abstract

Rhynchophorus ferrugineus is the serious insect pest of palm groves. Chemical control against this species is an important constituent for developing an IPM strategy. But repeated use of the same class of synthetic chemicals to control a pest can cause resistance. The research was conducted to evaluate resistance in R. ferrugineus against commonly used synthetic insecticides (chlorpyrifos, imidacloprid and lambda-cyhalothrin) with intense selection pressure for seven successive generations under laboratory conditions. Further, biochemical assays were performed after selection with chlorpyrifos (Chlor-SEL), imidacloprid (Imida-SEL), and lambda-cyhalothrin (Lam-SEL) from G1 to G7 to estimate possible resistance mechanism against tested insecticides. The Imida-SEL, Chlor-SEL and Lam-SEL showed very high resistance 1883-fold, 488-fold and 112-fold, respectively at G7 compared to the susceptible population. Biochemical results showed that the highest activity of AChE (71.43 μmol/min mg protein) was majorly contributed in imidacloprid resistance, EST in chlorpyrifos resistance (87.18 μmol/min mg protein) and GST (83.93 μmol/min mg protein) in lambda-cyhalothrin resistance. The outcomes of the present research propose that the increased levels of enzymes have their possible role for the resistance development in R. ferrugineus and their suppression can aid in the breaking of resistance. The rotation or replacement of chlorpyrifos, and imidacloprid with lambda-cyhalothrin can be integrated for the management of R. ferrugineus.