CYP450 Gene Cloning and Expression Patterns Induced by Two Neonicotinoid Insecticides in Megalurothrips usitatus

Cytochrome P450 (P450s) play a crucial role in insecticide detoxification and metabolic resistance in insects. In this study, we identified and characterized five P450 genes from the transcriptome of Megalurothrips usitatus, a major pest of leguminous crops. Full-length cDNA sequences were cloned and subjected to comprehensive bioinformatic analyses. The encoded proteins exhibited typical hydrophobic properties, with secondary structures dominated by α-helices and random coils. Notably, phosphorylation site prediction revealed a high frequency of serine residues. Phylogenetic analysis demonstrated close evolutionary relationships between these P450s and their orthologs in Frankliniella occidentalis and Thrips palmi. Bioassays revealed that field-collected M. usitatus populations from Haikou had developed moderate resistance to both dinotefuran (LC50 = 844.248 mg/L) and sulfoxaflor (LC50 = 165.991 mg/L). Quantitative real-time PCR analysis showed that CYP6EB24 expression was dramatically upregulated by 8.9-fold (p < 0.0001) and 9.6-fold (p < 0.0001) following exposure to LC25 concentrations of dinotefuran and sulfoxaflor, respectively. Spatiotemporal expression profiling indicated highest CYP6EB24 transcript levels in female adults and thoracic tissues. Correspondingly, cytochrome P450 enzyme activity increased significantly (p < 0.05) after insecticide treatment at LC50 concentrations. These results provide robust experimental evidence that CYP6EB24 plays a pivotal role in the metabolic detoxification of dinotefuran and sulfoxaflor in M. usitatus. Our findings not only advance the understanding of P450-mediated resistance mechanisms in M. usitatus but also establish a foundation for future functional studies of detoxification genes in this economically important pest species.