Using ten years of plant-pollinator interactions to study microbial and viral communities in subalpine bumble bees

The southern Rocky Mountains of Colorado are a regional hotspot for bumble bee (Bombus) diversity and home to 23 different species. Several of these bumble bee species are experiencing major declines, with parasites and pathogens acting as significant stressors. Bees can acquire parasites by visiting flowers that were previously contaminated by an infected bee, and observing pollinator visits can reveal how pathogens and other microorganisms are moving between bees. However, documenting these visitation patterns can be challenging, as observations are fleeting. These challenges can be overcome by long-term studies with extensive sampling. The University of Colorado Mountain Research Station hosts one of the longest running plant-pollinator network studies in a subalpine meadow. Using a decade of observations, we ask how well floral resource overlap between Bombus species can predict their microbial communities. We propose two hypotheses: 1) bees that share the most resources with each other will also have similar gut microbiota and virus communities, and alternatively, 2) bees more closely related to each other will have similar microbial communities, regardless of their interactions with other bees. Using 16S sequencing and RNAseq, we evaluate how the bacterial and viral communities differ between bumble bees and how microbial transfer may occur, potentially leading to novel management strategies for Bombus conservation.