Discussion
Despite the recognised influence that ongoing human driven changes on nitrogen and ozone availability have on plant communities (Fowleret al. 2013; Mills et al. 2013; Guerreiro et al.2014), little is known about how such changes impact pollinators and the services they provide to crop pollination, or how this interacts or is moderated by other drivers of pollinator decline. Recent studies showed that ozone pollution can impact directly and indirectly many fundamental ecological processes with consequences on biodiversity and sustainability of ecosystem services, such as pollination (Tai et al. 2014; Fuhrer et al. 2016; Duque et al. 2020; Emberson 2020). Here, we highlighted that ozone is part of a complex interacting system, mediating the strength of the effects pesticide exposure has on crop pollinators and the contribution of these pollinators to crop production. Below, we discuss in detail the potential mechanisms behind the patterns detected and the implications of our findings for conservation and management of crop pollination.