Overexpression of G protein-coupled receptors (GPCRs) contributing to lambda-cyhalothrin resistance in Cydia pomonella.

Abstract

G protein-coupled receptors (GPCRs) constitute a diverse and crucial family of membrane receptors, regulating a wide array of physiological processes. Although the involvement of GPCR signaling pathways in modulating key genes associated with insecticide resistance has been documented in various insect species, the molecular mechanisms underlying GPCR-mediated resistance in Cydia pomonella remain largely unknown. To elucidate the molecular basis of lambda-cyhalothrin (LCT) resistance in C. pomonella, we performed comparative transcriptome sequencing on whole-body, head, and midgut tissues of larvae from a susceptible population (SS) and a laboratory-selected LCT-resistant population (LCR) derived from SS. Five GPCR candidates (CpGPCRs) exhibiting overexpression in LCR were identified, including two members of family A (CpGPCR4 and CpGPCR55), two of family B (CpGPCR68 and CpGPCR76), and one of family F (CpGPCR94). Spatiotemporal expression profiling revealed that these genes were predominantly expressed during the first-instar larval and pupal-adult stages, with notably high expression levels in the larval heads. Notably, all genes exhibited significantly elevated expression in the midgut of LCR larvae compared to SS larvae. RNA interference (RNAi)-mediated knockdown of CpGPCR4, CpGPCR55, and CpGPCR68 increased larval susceptibility to LCT, while knockdown of CpGPCR4 and CpGPCR55 significantly reduced larval survival rates. Furthermore, larvae treated with dsGPCR55 exhibited molting defects and a decline in 20-hydroxyecdysone (20E) titers. These findings demonstrate that CpGPCRs play essential roles in the survival and development of C. pomonella and are critically involved in mediating resistance to LCT. This study enhances our understanding of the molecular mechanisms driving insecticide resistance and identifies potential targets for the development of novel pest management strategies against C. pomonella.