Dataset of pesticide and trace metal concentrations in the pollen provisions of wild bees and surrounding soils across European bee hotels

Wild bee populations are declining worldwide, with pesticides and trace metals identified as major drivers due to their widespread use in agriculture and their multiple anthropogenic sources (e.g., industry, traffic and renewable energy technology). Although studies investigating the effects of these pollutants on wild bees are increasing, most rely on concentrations measured in honeybee matrices to define field-realistic exposure levels. This approach may bias exposure assessments, as honeybees and wild bees differ substantially in their foraging ecology, potentially leading to different patterns of pollutant accumulation in pollen provisions. To address this gap, we deployed 79 bee hotels across four West European countries in various land-use contexts and screened 501 pesticides and seven trace metals, which led to the detection and quantification of 92 distinct pesticides and seven trace metals in pollen provisions collected from wild bees, as well as in soil samples surrounding the bee hotels. Overall, 56 and 68 pesticides were detected in pollen provisions and soil samples, respectively, while the seven screened trace metals were detected in both matrices, although prevalence and concentrations varied across bee hotels and soil samples. This dataset provides empirical field-realistic concentrations of pollutants in wild bee matrices, offering a robust reference for future laboratory and semi-field studies. It improves the ecological relevance and accuracy of exposure assessments in wild bee ecotoxicology and enables the investigation of potential links between soil contamination and pollutant levels in the pollen provisions of wild bees.