• Cytochrome P450 enzymes contributed to the resistance of B . tabaci to cyantraniliprole (CYA). • Five P450 genes were identified as overexpressed in four resistant strains. • The roles of the five P450 genes in CYA resistance were verified using RNAi and in vitro metabolism. The whitefly, Bemisia tabaci , is a major agricultural pest that has developed resistance to a broad range of insecticides. Despite the promising efficacy of cyantraniliprole (CYA) against B . tabaci , medium to high levels of resistance have emerged after prolonged field use. However, the mechanisms driving CYA resistance remain poorly understood. In this study, four B . tabaci strains exhibiting 24.9-fold to 28.9-fold resistance ratio to CYA were investigated. Synergist assays and enzyme activity measurements indicated cytochrome P450 enzymes contribute to this resistance. RNA sequencing and RT-qPCR analysis identified five P450 genes ( CYP305H2, CYP6EM1, CYP3133D3, CYP3133D5 , and CYP3133E2 ) as significantly overexpressed in resistant strains. Targeted silencing of these genes led to a 22.3% to 50.3% increase in CYA toxicity. The metabolic rates of these P450 enzymes against CYA were 2.5- to 6.0-fold higher than that in the control group within two hours. These results provide new insights into the molecular basis of CYA resistance in B . tabaci and highlight the pivotal role of cytochrome P450 enzymes in metabolic adaptation to diamide insecticides.
Xu et al. (Thu,) studied this question.