CYP450 Gene Cloning and Expression Patterns Induced by Two Neonicotinoid Insecticides in <i>Megalurothrips usitatus</i>

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.