Development of resistance to chlorantraniliprole represses sex pheromone responses in male Plutella xylostella (L.)

Abstract

The diamondback moth (DBM), Plutella xylostella (L.), is a serious pest that feeds on cruciferous crops. Prolonged exposure to insecticides has led to increased resistance and biological fitness alterations, such as reduced sensitivity to pheromones. However, the mechanisms underlying the influence of insecticides on sex pheromone recognition in male moths have not been elucidated. In this study, we found that male adults from the NIL strain (a chlorantraniliprole-resistant strain) showed decreased responses to sex pheromones at both the behavioral and electrophysiological levels compared to the SS strain (a susceptible strain) and the relative expression of the two pheromone-binding protein (PBP) genes ( PxPBP1 and PxPBP2) was downregulated in NIL compared to SS. Furthermore, downregulation of PxPBP1 and PxPBP2 by RNAi inhibited the responses of male moths to the sex pheromone at both the electrophysiological and behavioral levels. Fluorescence binding assays, homology modeling and molecular docking indicated that chlorantraniliprole could robustly bind both PxPBP1 and PxPBP2. The results indicated that the development of resistance to chlorantraniliprole reduced the response of DBM males to sex pheromones through the binding and downregulation of PxPBP1 and PxPBP2. This work provides new evidence for understanding the trade-offs between insecticide resistance and chemical communication as well as the fitness cost of insecticide resistance, in insects.