Decline in wild bee species richness associated with honey bee (Apis melliferaL.) abundance in an urban ecosystem

Abstract

The spatial heterogeneity of urban landscapes, relatively low agrochemical use, and species-rich floral communities often support a surprising diversity of wild pollinators in cities. However, the management of Western honey bees (Apis mellifera L.) in urban areas may represent a new threat to wild bee communities. Urban beekeeping is commonly perceived as an environmentally friendly practice or a way to combat pollinator declines, when high-density beekeeping operations may actually have a negative influence on native and wild bee populations through floral resource competition and pathogen transmission. On the Island of Montréal, Canada there has been a particularly large increase in beekeeping across the city. Over the years following a large bee diversity survey ending in 2013, there was an influx of almost three thousand honey bee colonies to the city. In this study, we examined the wild bee communities and floral resources across a gradient of honey bee abundances in urban greenspaces in 2020, and compared the bee communities at the same sites before and after the large influx of honey bees. Overall, we found a negative relationship between urban beekeeping, pollen availability, and wild bee species richness. We also found that honey bee abundance had the strongest negative effect on small (inter-tegular span <2.25 mm) wild bee species richness. Small bee species may be at higher risk in areas with abundant honey bee populations as their limited foraging range may reduce their access to floral resources in times of increased competition. Further research on the influence of urban beekeeping on native and wild pollinators, coupled with evidence-based beekeeping regulations, is essential to ensure cities contain sufficient resources to support wild bee diversity alongside managed honey bees.

Drivers of arthropod biodiversity in an urban ecosystem

“…Considering the ubiquity of feral and managed non-native honey bees throughout our study area, we think it is plausible that the negative effect of temperature on hover fly densities is a consequence of honey bee competition. This is compatible with recent results showing a negative effect of urban honey bees on native pollinators 56 .…”

Insect ecology and conservation in urban areas: An overview of knowledge and needs

“…Recent studies, however, suggest that a focus on Apis honeybees does little to raise awareness of insect conservation generally (Smith & Saunders, 2016). The impacts of this practice on local pollinator communities are still poorly understood (Casanelles‐Abella & Moretti, 2022; Graystock et al, 2016; MacKell et al, 2023) and may negatively impact the richness, abundance and activity of wild bees, even in areas of A. mellifera 's native range (MacInnis et al, 2023; Ropars et al, 2019). More research is critical to understanding the impacts and potential misuse of honey bees as a conservation flagship species.…”

How Informed Design Can Make a Difference: Supporting Insect Pollinators in Cities

“…In fact, wild bees are equally if not more critical for staple crop pollination (e.g., apples and blueberries [42]), and A. mellifera is non-native in most areas of the world and known to compete with native bees for limited floral resources [43]. While A. mellifera are the most frequently recorded and often the most abundant species in urban areas worldwide [29], an increase in urban beekeeping (hives specifically for A. mellifera) can negatively impact more diverse native bee assemblages in cities [44]. Thus, urban efforts to increase ecosystem services of pollination need to recognize the value of pollinator diversity to maintain services, as well as to consider the critical difference between managing habitat for pollinator services and preserving overall pollinator biodiversity [45].…”