Data from: Effects of live yeasts and their metabolic products on bumble bee microcolony development

Bumble bees can benefit from fungi, though the mechanisms underlying these
benefits remain unknown and could include nutrition, resource
supplementation, or pathogen protection. We tested how adding living
yeasts or their metabolic products to Bombus impatiens diets in a
factorial experiment affects microcolony performance, including survival,
reproduction, and pathogen presence. We additionally assessed the effects
of yeast treatments on diet (nectar and pollen) chemical composition using
untargeted metabolomics. Yeasts impacted microcolony reproduction and
survival, but effects depended on the source colony. Colonies containing
the putative pathogen Aspergillus showed reduced reproduction, but yeast
treatments reduced Aspergillus prevalence. Yeast treatments altered the
chemical composition of nectar and pollen, but most distinguishing
compounds were unidentified. Our results suggest limited direct effects of
yeasts via nutrition, resource supplementation, or modification of diets,
instead suggesting that yeasts may benefit bees through interactions with
the pathogens, including Aspergillus. Overall, the effects of yeast
supplementation are context-dependent, and more research is necessary to
better understand the factors important in determining their impacts on
bee hosts.