Effects of arsenic and selenium pollution on wild bee communities in the agricultural landscapes.

Wild bees play crucial roles in pollinating numerous crops and fruits worldwide. However, these essential insect pollinators are threatened with decline due to a variety of stressors. Among stressors, relatively little work has been done on metalloid pollution. Laboratory experiments have shown that arsenic (As) and selenium (Se) can negatively impact on bees, it is unknown if these effects translate in real-world environments. To address this knowledge gap, wild bee communities were sampled from 18 smallholder farmlands in Kaihua County in Quzhou, Southeast China and As and Se concentrations in three bee species were measured (Xylocopa tranquebarorum, Eucera floralia, and Apis cerana). Analyses revealed that the large carpenter bee, X. tranquebarorum, exhibited significantly lower As and Se concentrations than the other two wild bee species. No significant correlations were found between As and Se concentrations in all three wild bee species. Interestingly, the proportion of semi-natural habitat was found to be significantly related to reduced Se concentration in wild bee bodies, though no such effect was observed for As. As pollution negatively impacted bee diversity but not abundance, whereas Se significantly impacted neither bee diversity nor abundance. Furthermore, both As and Se pollution had no significant effect on the abundance of small-bodied wild bees. Given the essential role of wild bees for pollination services, monitoring of As and Se pollution in wild bee bodies and their food resources (pollen and nectar) is recommended across agricultural and other potentially impacted systems.