The effects of sub-lethal neonicotinoid pesticide exposure on pollination-relevant bee foraging behavior

Background/Question/Methods

Neonicotinoid pesticides, which have become the most widely used class of insecticides, are highly toxic to bees and have been shown to negatively impact bee behavior at very low levels. For instance, sub-lethal exposure may have negative impacts on worker lifespan, colony weight, and pollen collection. Yet we have little understanding of how sub-lethal neonicotinoid exposure alters floral fidelity, where bees temporarily specialize on one flower species. Floral fidelity is particularly important for plant reproduction, since it allows for conspecific pollen transfer. We examined whether floral fidelity is negatively impacted in the presence of neonicotinoid pesticides at concentrations typically found in agricultural fields in both social (Bombus impatiens) and solitary bees (Osmia lignaria). We performed laboratory foraging experiments in an automated chamber with artificial flowers and built-in RFID tag readers that allowed for exact tracking of bee movements. For all experiments, we compared neonicotinoid-exposed bees with unexposed controls.

Results/Conclusions

We continue to gather data, but preliminary results show that floral fidelity is reduced by sub-lethal pesticide exposure in both social (Bombus) and solitary bees (Osmia). Floral fidelity of Osmia is disproportionately impacted by sub-lethal neonicotinoid exposure compared to larger-bodied bumble bees (Bombus). These results indicate that neonicotinoid pesticides may decrease the quality of pollinators in terms of plant pollination services. This is important for informing pesticide management while promoting sustainable agriculture and preservation of pollinator-dependent plant communities.