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Q&A ViewAttendees 4

Plant-Insect Ecosystems

Student Competition 10-Minute Paper

Grad P-IE: Ecology 3

Fungicide impacts on bumble bees are mediated via effects on bee-associated fungi

Monday, November 1, 2021
11:30 AM - 11:42 AM MT
Location: Colorado Convention Center, Meeting Room 210-212
In-Person Student Competition
Native bees including bumble bees are important pollinators but face threats from multiple sources, including agrochemical application. Declining bumble bee populations have been linked to fungicide application, which could directly affect the fungi often found in the stored food and GI tract of healthy bumble bees. Here, we test the hypothesis that fungicides impact bee health by disrupting bumble bee -fungi interactions. Using two species, Bombus vosnesenskii and B. impatiens, we test the interactive effect of the fungicide propiconazole and fungal supplementation on the survival, reproduction, and microbiome composition of microcolonies (queenless colonies). We found that both bee species benefitted from fungi, but were differentially affected by fungicides. In B. vosnesenskii, fungicide exposure decreased survival while fungal supplementation mitigated fungicide effects. For B. impatiens, fungicide application had no effect, but fungal supplementation improved survival and offspring production. Fungicides altered fungal microbiome composition in both species, and reduced fungal abundance in B. vosnesenskii microcolonies, but not in B. impatiens, where instead fungal addition actually decreased fungal abundance. Our results highlight species-specific differences in both response to fungicides and the nature of fungal associations with bees, and caution the use of results obtained using one species to predict the responses of other species. These results suggest that fungicides can alter bee- fungi interactions with consequences for bee survival and reproduction, and suggest that exploring the mechanisms of such interactions, including interactions within bee-associated fungal communities, may offer insights into bumble bee biology and bumble bee conservation strategies.