As urban areas continue to expand globally, animal biodiversity is likely to experience altered habitat conditions, resource levels, and pathogen dynamics, with critical implications for insect pollinators. Specifically, local and regional land management may impact pollinator infectious disease prevalence, and this may be particularly relevant in urban garden systems where local food production depends on crop pollination. Further, because multi-host parasites can be spread across insect pollinator communities with varying impacts on host species, changes in pollinator community composition can lead to ‘amplification’ or ‘dilution’ effects, whereby increases in pollinator diversity could lead to higher or lower rates of parasitism, respectively. In this study, we investigate how urban garden management and regional landscape composition structure disease dynamics for a critical native pollinator, the bumble bee Bombus vosnesenskii. Parasite prevalence in our gardens was low in Nosema ceranae (1.06%) and Nosema bombi (1.06%), and Crithidia expoekii (0.5%), while we observed higher prevalence of Crithidia bombi (18%) and Apicystis bombi (6.4%). We found that gardens with higher pollinator taxonomic richness had significantly lower prevalence of Apicystis bombi in B. vosnesenskii hosts, providing evidence for the dilution effect. We also found that the prevalence of the parasite Crithidia bombi was significantly higher in gardens with higher mulch use and in gardens surrounded by greater proportions of impervious urban cover. Overall, we document a wide range of stressors facing urban bees, and show that parasitism is mediated by local ground management, regional land use, and pollinator community composition.