Combined exposure to flupyradifurone and microplastics: differential toxicity across three pollinator species

Abstract BACKGROUND Multiple stressors have been identified as threats to pollinators, many of which are related to human activities. Pesticides are among the most studied stressors affecting pollinators, whereas microplastic residues represent an emerging and less studied threat. This study investigated the combined effects of polystyrene microplastics and the pesticide flupyradifurone on three pollinator species: Apis mellifera ligustica , Bombus terrestris , and Eristalis tenax . Acute oral toxicity tests were conducted by feeding individuals with different doses of flupyradifurone alone or in combination with a fixed concentration of microplastics. RESULTS The median lethal dose (LD 50 ) of flupyradifurone differed among species. In A. mellifera , the LD 50 was 0.91 μg/insect (95% confidence interval (CI): 0.38–1.20). In B. terrestris , the LD 50 decreased from 46.10 μg/insect (95% CI: 37.55–59.02) to 31.17 μg/insect (95% CI: 25.66–38.11) in the presence of microplastics, showing a different response under co‐exposure. For E. tenax , a reliable LD 50 could not be estimated. Only the highest tested dose (4.8 μg/insect) caused significantly higher mortality than the control, with no effect of microplastics. CONCLUSION Acute mortality was mainly related to flupyradifurone exposure, while the effect of polystyrene microplastics differed among species. In B. terrestris , the presence of microplastics was associated with a lower LD 50 , suggesting that interactions between microplastics and pesticides may differ among pollinator species. Longer‐term studies are needed to better understand the potential effects of microplastics on pollinators. © 2026 Society of Chemical Industry.