Molecular response of Tribolium castaneum to benzothiazole: insights from transcriptome and functional validation of UGT2B9

Abstract BACKGROUND Benzothiazole has been identified as a potential grain fumigant against Tribolium castaneum , though its insecticidal mechanism requires further investigation. In this study, sixth‐instar larvae of T. castaneum were exposed to benzothiazole at LC 30 and LC 50 concentrations for 24 h. RESULTS Neither concentration caused sustained inhibition of larval respiratory rate, ATP content, or mitochondrial membrane potential over the 24 h exposure period. RNA‐seq analysis identified 392 differentially expressed genes common to both LC 30 (50.96 μL L −1 ) and LC 50 (108.86 μL L −1 ) treatments. Protein–protein interaction analysis of these shared genes revealed three core genes all encoding 4‐coumarate‐CoA ligase (4CL). In larvae, benzothiazole exposure upregulated genes in pathways related to protein digestion and absorption, juvenile hormone hydrolysis, detoxification and cuticle formation, but downregulated genes in carbohydrate metabolism. Among the key genes involved, UDP‐glucuronosyltransferases (UGTs) participated in multiple enriched pathways and emerged as a common responsive gene family in both T. castaneum and the Dipteran insect Bradysia odoriphaga . RNAi‐mediated silencing of UGT2B9 , 4CL , or extensin demonstrated that only knockdown of UGT2B9 significantly increased larval susceptibility to benzothiazole. CONCLUSION These findings provide insights into the potential multifaceted insecticidal action of benzothiazole in T. castaneum at the transcriptomic level and support its further development as a target‐specific grain fumigant. © 2026 Society of Chemical Industry.