Stress responses in the honeybee (Apis mellifera L.) midgut triggered by PFOA and PFHxS at environmental residue concentrations detected in bee products

Perfluorooctanoic acid (PFOA) and perfluorohexane sulfonate (PFHxS), as persistent global contaminants, pose substantial threats to pollinators like honeybees ( Apis mellifera L.), yet their sub-lethal effects remain insufficiently explored. Here, we exposed bees to environmentally relevant concentrations (0.5–50 μg/L) of PFOA and PFHxS for 10 days, assessing midgut toxicity through pathology, metabolomics, and gene expression, and examined curcumin (Cur) as a potential mitigator. Although acute toxicity assays indicated relatively high LC₅₀ values (266–331 mg/L), sub-lethal exposures induced pronounced midgut injury, characterized by decreased epithelial cell density and thinning of the protective gel layer. Disruption of glycerophospholipid metabolism was detected, impairing membrane integrity. Additionally, PFOA and PFHxS downregulated barrier integrity genes ( ZO-2 and Mucin-1 ), while upregulating inflammatory ( Eiger and Relish ) and apoptotic indicators ( Caspase-3 , Caspase-8 , and Caspase-9 ). For several sub-lethal endpoints, PFHxS triggered more pronounced effects than PFOA. Notably, curcumin treatment restored midgut integrity and reversed many of the associated molecular disruptions. These results demonstrated that environmentally relevant concentrations of PFAS could substantially compromise honeybee gut health, offering critical insights for ecological risk assessments aimed at safeguarding these essential pollinators.