Jingliang Shi

Limited understanding of the enantioselective toxicity mechanism of chiral pesticides hinders honeybee protection. S-Ethiprole posed high toxicity to honeybees, yet its mechanism remains unknown. We investigated the enantioselective mechanisms of rac-, R-, and S-ethiprole on honeybees following 7 day exposure at 15 μg/L, using metabolomics, enzymatic assays, qPCR, molecular docking, and molecular dynamics simulations (MD). The results indicated that rac-, R-, and S-ethiprole induced differential perturbations of honeybee metabolism. Notably, S-ethiprole significantly downregulated CYP450 genes expression, decreased CYP450 content, and impaired the metabolism of xenobiotics by CYP450 to a greater extent than rac- and R-ethiprole. Consistently, molecular docking showed that S-ethiprole exhibited broader but weaker affinity for sensor proteins in detoxification-related transcriptional regulatory pathways than R-ethiprole. Moreover, MD suggested that the specific binding of S-ethiprole to Keap1 may inhibit activation of the CncC/Keap1 pathway. Our research provided valuable insights into guiding ethiprole use strategies to protect honeybee health.

Acetamiprid is a third-generation neonicotinoid insecticide that is now widely employed for the protection of crops grown in outdoor environments. This is because it is considerably less toxic to pollinating insects than other neonicotinoids. Previous studies have shown that acetamiprid has direct physiological effects on adult and larval bees. However, its effects on the potentially healthy gut microbiota of honeybees have not been fully elucidated. To further investigate the effects, adult and larval worker honeybees were exposed to sucrose solutions containing acetamiprid at concentrations of 0, 5, and 25 mg/L for a period of 7 days (adults) and 4 days (larvae). The results showed that acetamiprid exposure significantly disrupted the honeybees’ intestinal microbiota. In adults, acetamiprid exposure led to a significant increase in the relative abundance of Commensalibacter, while the Bifidobacterium and Gilliamella levels decreased. In larvae, we observed significant changes in the microbial composition, notably a marked reduction in Bombella. Further analysis demonstrated that alterations in the gut microbiota of honeybee larvae were associated with disturbances in metabolic pathways that regulate energy metabolism and neurometabolism. These results suggest that acetamiprid affects bee health not only through direct physiological effects, but also through changes in the gut microbiota, which in turn affect the metabolic and immune function of bees. This study underscores the need to evaluate pesticides’ risks from a microbiological standpoint and offers crucial insights into how acetamiprid impacts bee health by modifying the gut microbiota. These insights support the more comprehensive assessment of acetamiprid and similar pesticides regarding bee health.