Ecological traits interact with landscape context to determine bees' pesticide risk

Widespread contamination of ecosystems with pesticides threatens non-target organisms. However, the extent to which life-history traits affect pesticide exposure and resulting risk in different landscape contexts remains poorly understood. We address this for bees across an agricultural land-use gradient based on pesticide assays of pollen and nectar collected by Apis mellifera, Bombus terrestris and Osmia bicornis, representing extensive, intermediate and limited foraging traits. We found that extensive foragers (A. mellifera) experienced the highest pesticide risk-additive toxicity-weighted concentrations. However, only intermediate (B. terrestris) and limited foragers (O. bicornis) responded to landscape context-experiencing lower pesticide risk with less agricultural land. Pesticide risk correlated among bee species and between food sources and was greatest in A. mellifera-collected pollen-useful information for future postapproval pesticide monitoring. We provide foraging trait- and landscape-dependent information on the occurrence, concentration and identity of pesticides that bees encounter to estimate pesticide risk, which is necessary for more realistic risk assessment and essential information for tracking policy goals to reduce pesticide risk. Analysing pesticide residues in pollen and nectar collected by three bee species along a land-use gradient, the authors show that extensive foragers like Apis mellifera have higher pesticide risk than species that forage at intermediate or limited ranges, irrespective of landscape context.

Automated summary

Widespread pesticide contamination threatens non-target organisms in ecosystems. This study examines how life-history traits and landscape context influence pesticide exposure and risk for bees across an agricultural land-use gradient. The findings show that extensive foragers like Apis mellifera face the highest pesticide risk, while species with intermediate or limited foraging ranges respond to landscape context with reduced pesticide risk. The study provides essential information for future pesticide monitoring and realistic risk assessment to track policy goals for reducing pesticide risk.