Field‐dose fenitrothion impairs gut function and survival in the bumble bees ( <scp> <i>Bombus terrestris</i> </scp> )

BACKGROUND: Fenitrothion is a widely used insecticide, yet its effects on the health of bumble bees (Bombus terrestris) have not been reported until now. We carried out experiments to investigate the impact of field-realistic concentrations of fenitrothion on food consumption, body weight, survival probability, gut structure, gut detoxification enzyme activity, gut microbial diversity, gut transcriptional and gut metabolic profiles of Bombus terrestris. RESULTS: fenitrothion significantly reduced survival probability, induced gut damage as evidenced by hematoxylin and eosin staining, decreased cytochrome P450 (P450) activity while increasing glutathione S-transferase (GST) activity, and down-regulated AChE1 expression in gut tissue. Furthermore, 16S rRNA sequencing revealed a decline in gut microbial diversity, while transcriptomic and metabolomic analyses indicated disruptions in gut gene and metabolic expression. Molecular docking revealed that fenitrothion binds within a hydrophobic pocket formed by residues Trp148, Ser186, Tyr185, and Gly182 of the AChE1 protein. CONCLUSION: These multiple sublethal alterations in bee behavior and physiology indicate that fenitrothion is likely to exert complex yet detrimental effects on Bombus terrestris health under field conditions. © 2026 Society of Chemical Industry.