Worldwide, bee conservation faces threats from pathogens, habitat alteration, and resource limitation, among other factors. These three stressors are mediated by a combination of anthropogenic forces as well as the community and population dynamics of hosts and parasites. One increasingly widespread habitat where these three stressors may be particularly impactful are urban habitats, which can have positive and negative impacts on pollinator communities, depending on local and landscape management. However, little is known about how urban management impacts infectious disease prevalence in wildlife, which is especially pertinent in urban garden systems where local food production depends on the services provided by the pollinator community. While floral resources within urban gardens may act to provision urban pollinator populations, it may also lead to pollinator aggregation and increased health risks. In this study, we show that urban garden management and regional landscape composition play key roles in structuring the disease dynamics in critical native pollinators. Specifically, we found that parasitism in B. vosnesenskii is directly influenced by the intensity of local garden management practices and regional land-use patterns, where higher management intensity and higher proportion urban cover leading to higher rates of parasitism. We also found that diversity in the local pollinator community reduces parasite prevalence in B. vosnesenskii, providing another example of the dilution effect in a natural experiment. Overall, we documented slightly lower rates of infection than have previously been documented in this region, indicating some stochasticity in the interaction between bumblebee hosts and their parasites.
