Toxicity of the insecticide sulfoxaflor alone and in combination with the fungicide fluxapyroxad in three bee species

Dataset for the pubblication: https://doi.org/10.1038/s41598-021-86036-1 

Abstract:

The sulfoximine insecticide sulfoxaflor is regarded as a potential substitute for neonicotinoids thatwere recently banned in the EU due to their side effects on bees. Like neonicotinoids, sulfoxafloracts as a competitive modulator of nicotinic acetylcholine receptors. In agricultural environments,bees are commonly exposed to combinations of pesticides, and neonicotinoids are known to interactsynergistically with fungicides. The objective of our study is to assess the acute oral toxicity ofsulfoxaflor alone and in combination with a single dose of fluxapyroxad, a succinate dehydrogenaseinhibitor (SDHI) fungicide, in three bee species: Apis mellifera, Bombus terrestris and Osmia bicornis.Because synergism may be dose-dependent, we tested a range of sulfoxaflor doses. Synergisticeffects were assessed using three different approaches: Bliss criterion of drugs independence, ratiotest comparing LD50s and model deviation ratio. Osmia bicornis was the most sensitive species tosulfoxaflor and both O. bicornis and A. mellifera showed significant synergism between the insecticideand the fungicide. For the most part, these synergistic effects were weak and only occurred at earlyassessment times and intermediate sulfoxaflor doses. The potential ecological relevance of theseeffects should be confirmed in field and/or cage studies. Overall, our laboratory results demonstratethat sulfoxaflor is somewhat less toxic than the recently banned neonicotinoids imidacloprid,thiamethoxam and clothianidin, but much more toxic than other neonicotinoids (acetamiprid,thiacloprid) still in use in the EU at the time this study was conducted.