Pesticides and Their Impacts on Wild Bee Populations

Wild bees are a vast and diverse group of Hymenoptera that provide crucial ecosystem and economic services, including the pollination of both wild plants and crops. Unfortunately, many species of wild bees have been facing progressive declines in recent years, endangering their valuable services. This alarming disappearance is driven by multiple factors of anthropogenic origin. Among these factors, pesticides play a pivotal role as drivers of this loss. However, accurately assessing the impact of agrochemicals on these important insects is challenging due to limited data on their presence and abundance in both natural and managed environments. Furthermore, the official risk-assessment guidelines for evaluating pesticide safety use very few representative species of commercial bee pollinators as models and do not account for the wide diversity in the life histories and habits of these taxa, which are likely to result in different sensitivities to pesticides. In the present chapter, we provide the available knowledge on the link between wild bees’ decline and the impact of pesticides, highlighting the harmful effects that these products can have on different groups of bees. We point out the current weaknesses in pesticide risk-assessment protocols concerning these taxa and the recent efforts to update and implement them. Finally, we focus on sustainable alternatives and practices to mitigate the deleterious effects of pesticides on wild bees, enhance their conservation, and ensure their survival, thereby maintaining the crucial ecological and economic services that they provide.