Sessions

Bumblebees (Bombus spp.) play a key role in pollination and in maintaining the functioning of ecosystems, although, in the recent decades, global declines have been observed in both their populations and species richness. One of the reasons of this decline is the excessive use of pesticides, which poses a threat to pollinating insects. Due to intensive agricultural production, pesticides are being used frequently, including insecticides containing the active substance flupyradifurone. This insecticide is often considered “bee-friendly,” but as a systemic substance, it can be found in the nectar and pollen of flowers that attract bees. In This study, we examined the foraging behaviour and chemosensory perception of buff-tailed bumblebee (Bombus terrestris L.) workers after one, two, and three weeks of exposure to the insecticide Sanium System, which contains flupyradifurone. Foraging behaviour was tested in a wind tunnel, while the sensitivity of the olfactory perception was measured using electroantennography (EAG). Our results showed that pesticide-treated bumblebees approached any scent sources less frequently and later compared to the control animals. However, the treatment did not affect which scent source (a floral blend associated with a nutritional reward or the mineral oil control) they first choose, or the time taken to initiate foraging . The EAG measurements revealed that antennal responses to the floral blend were dose-dependent, but pesticide treatment did not affect its magnitude either directly or in interaction with exposure length. Overall, our results indicate that flupyradifurone may reduce the foraging motivation of worker bumblebees, but does not impair their chemosensory perception. Further research is needed to determine whether the sublethal effects of flupyradifurone exposure observed in our study may contribute to the decline of wild bumblebee populations.