Relationship between plant community composition and disease dynamics in a multi-host system

Pollinator habitats can be designed to address multiple stressors while increasing the abundance and richness of pollinators. Increasing the proportion of Asteraceae in conservation habitat may help decrease infection by the bee gut pathogen Crithidia in a bee community. Previous research has found that Asteraceae pollen diets (compared to mixed pollen diets) and high sunflower abundance near farms (compared to low sunflower abundance) reduced Crithidia infection in the common eastern bumble bee (Bombus impatiens). However, how the proportion of Asteraceae plant species in a conservation habitat affects bee pathogen infection, pollinator richness and abundance is unknown. We measured plant and pollinator community traits in 20 pollinator habitats in the eastern United States. We hypothesized that pollinator habitats with a higher proportion of Asteraceae floral resources would have reduced prevalence and intensity of Crithidia infections in B. impatiens but maintain similar pollinator richness and abundance compared to habitats with lower Asteraceae resources. We found that Crithidia prevalence and intensity in B. impatiens was not correlated with Asteraceae richness and abundance. However, a higher percentage of Asteraceae floral richness in pollinator habitats was associated with increased bee and non-bee pollinator abundance, as well as non-bee pollinator richness. We are continuing to analyze whether Crithidia prevalence and intensity is better predicted by previous floral composition, due to lags in disease development. In conclusion, while Asteraceae floral resources did not affect Crithidia infections in B. impatiens, habitats with high Asteraceae species richness supported pollinator richness and abundance.