Bees have evolved mutualistic associations with plants, but flowers also expose bees to parasites and pesticides. It is unknown how floral foraging traits influence bee decline. We collected 11 species of wild bees (n=866) from sunflower farms in Yolo County that vary in local and landscaped features. We extracted DNA from each sample and tested each bee for Crithidia spp., Nosema spp., Apicystis spp., Aspergillus spp., and Ascosphaera spp. We analyzed pesticide residue representative samples from each species. We examined the composition of bacteria in the gut microbiome of each specimen and the plant species present in the pollen using Illumina Miseq sequencing.
Results/Conclusions
Preliminary data indicates that bees vary in their parasite communities (e.g. 20.32% of all specimens tested positive for Aspergillus fungus (n=310) but Svastra obliqua significantly hosts more Aspergillus than other bees (p<0.01)). To understand how flowers shape bee-microbe and bee-parasite interactions, we will use a network approach to model interaction patterns between bees, their plant partners, their parasites, and their microbes. We examine how foraging generalization, centrality, and niche overlap influence parasite load using linear models. To examine how microbiome and parasite community composition are influenced by network characteristics, we use simple Mantel tests to compare dissimilarity correlations between the following: plant-parasite communities, microbe-parasite communities, and plant-microbe communities. Theory predicts that generalist species are less vulnerable to the extinctions of their mutualistic partners. Our work may complicate this theoretical assumption if generalists also host more parasites.