Utilizing cationic liposome to co-deliver poly-siRNA and chlorantraniliprole complexes: A new strategy for overcoming insecticide resistance in Plutella xylostella (Lepidoptera: Plutellidae)

The diamondback moth ( Plutella xylostella ) is a widely distributed pest recognized for its damaging effects on cruciferous crops and its rapid development of resistance to insecticides, particularly chlorantraniliprole (CAP). This study aims to develop new strategies for managing CAP resistance through the co-delivery of CAP and poly-siRNA targeting cytochrome P450 (CYP) genes. Utilizing a cationic liposome (CTL), we developed a unique co-delivery system for CTL-CAP/poly-siRNA-CYP complexes, characterized by an average particle size of 705 nm, a surface charge of +25 mV, and an impressive polydispersity index (PDI) of 0.12, demonstrating good formulation quality. Feeding bioassays revealed a remarkable capacity of these complexes to suppress CYP genes ( CYP6BG1 and CYP6BF1v4 ) expression in both the moderately CAP-resistant (CAP-SJ) and highly resistant (CAP-QP) P. xylostella , resulting in an about 30 % enhancement in CAP efficacy compared to the control group. This synergistic approach is among the first to combine RNAi and insecticides to combat resistance in this pest. This groundbreaking research not only introduces an innovative method for integrating RNAi-mediated gene silencing with chemical insecticides, but also significantly improves the effectiveness of CAP against resistant P. xylostella populations. Text summarizing: A CTL-based co-delivery system combining poly-siRNA and CAP successfully targeted cytochrome P450 resistance genes and enhanced chlorantraniliprole efficacy against Plutella xylostella . • RMS treatments silenced key CYP genes ( CYP6BG1 , CYP6BF1v4 ) in CAP-resistant P. xylostella . • CTL-CAP/poly-siRNA-CYP complexes showed stable size, charge, and PDI for effective delivery. • Poly-siRNA complexes enhanced CAP efficacy by ∼30% in resistant P. xylostella strains. • CYP6BF1v4 contributes more strongly than CYP6BG1 to CAP resistance in P. xylostella .