D3488: Floral composition of pollen collected from rusty patched bumble bee (Bombus affinis, Cresson) nests in southeastern Minnesota

Tuesday, November 12, 2024

9:00 AM – 5:00 PM MST

Location: Phoenix Convention Center, Exhibit Hall 6, PCC

Presenting Author(s)

Elaine Evans (she/they)

Extension Professor
University of Minnesota
Saint Paul, Minnesota

Co-Author(s)

MS

Michael Simanonok

United States Geological Survey
Jamestown, North Dakota
CO

Clint Otto

Research Ecologist
U.S. Geological Survey
Jamestown, North Dakota
RC

Robert Cornman

U.S. Geological Survey
Fort Collins, Colorado
DI

Deborah Iwanowicz

United States Geological Survey
Kearneysville, West Virginia
TS

Tamara Smith

United States Fish and Wildlife Service
Minneapolis, Minnesota

Understanding the forage diets of imperiled bumble bees can improve conservation planning and habitat restoration efforts. In this study we describe the taxonomic composition of bee-collected pollen from two rusty patched bumble bee (Bombus affinis, Cresson) nests located in Southeastern Minnesota. This is the first published reporting of pollen collected from an active B. affinis nest. We also compared pollen identification via traditional palynological light microscopy with genetic identification via ITS metabarcoding. Among the 49 pollen samples analyzed, we detected 41 and 56 distinct taxa via light microscopy and metabarcoding, respectively; 27 of 47 total genera overlapped between the two methods bittersweet nightshade (Solanum dulcamara) was the most detected species for both metabarcoding and microscopy identification for pollen prevalence. Pollen volume from the microscopy data showed that lesser burdock(Arctium minus), alfalfa (Medicago sativa), bittersweet nightshade (Solanum dulcamara), plumeless thistle (Carduus acanthoides), and red clover (Trfolium pratense) together comprised more than half of the total volume of pollen. Light microscopy and metabarcoding revealed compositionally distinct plant communities when analyzed at the species level. Methodological concordance improved when analyzing pollen data at genus level, but both methods still reveal marginally distinct groupings. Our study highlights specific plant taxa that are important components of B. affinis pollen diets and provides actionable research for conservation efforts in urban systems. Our study also supports the hypothesis that B. affinis is a generalist forager and will collect pollen from a variety of native and non-native host plants.