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 , As and Se concentrations in three bee species were measured (Xylocopa tranque-barorum, Eucera floralia, 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 cor-relations 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.

Automated summary

Wild bees are essential for pollinating crops and fruits worldwide, but they are facing decline due to various stressors. This study focuses on the impact of metalloid pollution, specifically arsenic (As) and selenium (Se), on wild bee communities in Southeast China. The results show that metalloid concentrations in wild bees varied among species, with the large carpenter bee having significantly lower levels than the other two species. The proportion of semi-natural habitat was found to be significantly related to reduced selenium concentration in wild bee bodies. Arsenic pollution negatively affected bee diversity, but not abundance, while selenium had no significant impact on diversity or abundance. Therefore, monitoring metalloid pollution in wild bees and their food resources is recommended.