Li_2026_Pestic.Biochem.Physiol_216_106743

Wolbachia, a maternally transmitted intracellular symbiont widely distributed in arthropods, regulates diverse host functions including detoxification. Eucryptorrhynchus scrobiculatus Motschulsky (Coleoptera: Curculionidae) as a specialist borer pest of Ailanthus altissima (Mill.) Swingle, it exclusively damages the host tree through larval boring and adult supplemental feeding, constituting a major wood-boring insect in China's forestry ecosystems. This study investigated the role of Wolbachia in modulating the detoxification capacity of E. scrobiculatus. Fluorescence in situ hybridization (FISH) and quantitative PCR (qPCR) analyses demonstrated that 21-day tetracycline treatment (15 mg/mL) effectively eliminated Wolbachia (99.96 % reduction). Compared to symbiotic controls, Wolbachia-depleted weevils exhibited significantly reduced activities of cytochrome P450 monooxygenases (P450) and glutathione S-transferase (GST), while carboxylesterase (CES) activity increased. Subsequently, transcriptomic analysis further revealed that Wolbachia-depleted weevils exhibited diminished expression of the detoxification gene EscrGST1 and reduced tolerance to the insecticides imidacloprid and cypermethrin. RNA interference (RNAi) silencing of EscrGST1 induced a compensatory increase in Wolbachia abundance during gene suppression, demonstrating a bidirectional regulatory mechanism between symbiont dynamics and host detoxification pathways. These findings demonstrate that Wolbachia mediates pesticide resistance in E. scrobiculatus by modulating EscrGST1 activity, providing novel strategies for controlling E. scrobiculatus, and offering new perspectives for developing pest control approaches through targeted disruption of symbiotic relationships.