Honey bees are essential for pollination, but their health is threatened by various environmental factors, including pesticides. This study investigates how antibiotics disrupt the gut bacteria of honey bees and increase their vulnerability to the pesticide imidacloprid. We found that bees treated with antibiotics had fewer beneficial gut bacteria, which led to higher death rates when exposed to the pesticide. Changes in gut bacteria also affected the bees' metabolism and immune response. Adding a specific nutrient helped reduce deaths from pesticide exposure, highlighting the importance of healthy gut bacteria for bee survival. This research shows that using antibiotics alongside pesticides can pose serious risks to honey bee populations.
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The honey bee (Apis mellifera) plays a vital role in global pollination, yet its health is increasingly threatened by multiple environmental stressors. Among these, the molecular interactions between gut microbiota disruption and pesticide exposure remains insufficiently understood. Here, we showed that tetracycline-induced gut microbiota dysbiosis significantly increased bee susceptibility to imidacloprid, leading to premature mortality. Microbiota-depleted bees also exhibited higher mortality under imidacloprid stress, confirming the protective role of a stable gut community. Taxonomic and functional analysis revealed pronounced shifts in bacterial composition, notably the reduction of Gilliamella and Bartonella and the enrichment of Lactobacillus and Commensalibacter, accompanied by broad perturbations in amino acid and carbohydrate metabolism in dysbiotic bees exposed to imidacloprid. Key metabolites with antioxidant and protective functions, including alanyl-glutamine, serotonin, and shikimic acid, were markedly reduced in the gut microbiota dysbiosis-imidacloprid group and correlated with changes in core bacterial taxa. Consistently, immune, detoxification, and nutritional genes were downregulated in bees with disturbed microbiota, indicating weakened antioxidant defense and metabolic capacity. Notably, dietary supplementation with alanyl-glutamine mitigated imidacloprid-induced mortality in honey bees, suggesting that restoring microbiota-derived metabolic functions could enhance host resilience towards imidacloprid toxicity. These findings provide direct evidence that gut microbiota integrity is critical for mitigating imidacloprid stress, and that disturbances in microbial balance heighten honey bee vulnerability to imidacloprid. This work underscores the ecological risk of combined antibiotic-pesticide exposure and emphasizes the microbiome's role as a key mediator of pollinator resilience.
