Identification and Expression Analysis of the Cytochrome P450 Genes in Phyllotreta striolata and CYP6TH1/CYP6TH2 in the Involvement of Pyridaben Tolerance

The striped flea beetle, <i>Phyllotreta striolata</i>, is a worldwide pest that causes severe damage to cruciferous crops. Pyridaben, an inhibitor of mitochondrial complex I, has been widely used for the control of <i>P. striolata</i>. Identifying key genes involved in pyridaben tolerance is vital for establishing effective resistance management strategies. A total of 94 full-length cytochrome P450 (CYP) genes were identified in <i>P. striolata</i>. The identified genes were classified into four clans (mitochondrial, CYP2, CYP3, and CYP4), 23 families, and 57 subfamilies. Transcriptomic analysis across developmental stages and tissues revealed distinct expression patterns were seen in these P450 genes. Pyridaben exposure significantly upregulated the expression of <i>CYP6TH1</i> and <i>CYP6TH2</i>. Tissue-specific expression profiling indicated that <i>CYP6TH1</i> and <i>CYP6TH2</i> were highly expressed in the head and fat body. RNA interference-mediated knockdown of these genes significantly increased the susceptibility of <i>P. striolata</i> to pyridaben. Molecular docking confirmed stable binding between pyridaben and both CYP proteins, with binding free energies of -7.73 and -7.57 kcal/mol for CYP6TH1 and CYP6TH2, respectively. This study demonstrates that CYP6TH1 and CYP6TH2 play critical roles in pyridaben tolerance in <i>P. striolata</i>, which highlights promising genetic targets for future resistance management strategies.