Characterization of CYP402C5 associated with field resistance to three neonicotinoids in Bemisia tabaci

The widespread use of neonicotinoid insecticides has resulted in extensive resistance in field populations of the whitefly Bemisia tabaci, posing a major challenge to sustainable pest management. However, the molecular basis of cross-resistance to multiple neonicotinoids remains to be fully elucidated. In this study, resistance levels to thiamethoxam, thiacloprid, and nitenpyram were evaluated in eleven field populations of B. tabaci MED collected over a two-year period from vegetable fields in multiple provinces of China. Comparative transcriptomic analysis identified CYP402C5 as a candidate cytochrome P450 gene consistently overexpressed in resistant populations. RNA interference-mediated silencing of CYP402C5 significantly increased the susceptibility of resistant populations to all three neonicotinoids but had little effect on the susceptible strain, indicating its important role in neonicotinoid resistance. Structural prediction and molecular docking suggested that CYP402C5 possesses a conserved P450 catalytic pocket capable of accommodating multiple neonicotinoids. Functional characterization using a baculovirus expression system, coupled with UPLC-MS/MS analysis, demonstrated NADPH-dependent metabolism of thiamethoxam, thiacloprid, and nitenpyram by recombinant CYP402C5. Moreover, the identification of a nitenpyram-derived metabolite (NIT-IM) provided direct evidence for CYP402C5-mediated biotransformation. Collectively, these results demonstrate that CYP402C5 functions as a neonicotinoid-detoxifying P450 enzyme and contributes to cross-resistance in B. tabaci. This study expands the repertoire of resistance-associated P450 genes in B. tabaci and provides valuable insights for resistance monitoring and neonicotinoid resistance management.