Data from: Parasitism of urban bumble bees influenced by pollinator taxonomic richness, local garden management, and surrounding impervious cover

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.