Floral resource availability and surrounding land cover influence bumble bee community composition in an agricultural landscape

Agricultural intensification and the loss of floral resources are suspected factors in bumble bee declines in North America. Understanding the effects of land use on bumble bee communities at the local and landscape scale is important to support conservation efforts.

We surveyed 55 prairie and grassland sites in a highly agricultural landscape in 2023 and 2024. We used a multispecies occupancy model to estimate effects of site characteristics on both community‐level and species‐level occupancy probability. We also evaluated the relationship between species richness and the land cover within 1.6 km of sites.

We detected 13 species of bumble bees, including four that are threatened or endangered. Bumble bee community occupancy probability was positively associated with local plant diversity ( β  = 0.545, 95% CRI: 0.0293, 1.22) and was generally higher in more forested landscapes ( β  = 0.530, 95% CRI: −0.0727, 1.24), but this varied greatly among species.

Species richness was significantly lower at sites with high corn/soybean land cover (Spearman's rank correlation coefficient ρ  = −0.318, 95% CRI: −0.570, −0.0705) and significantly greater at sites with high forest cover within 1.6 km ( ρ  = 0.491, 95% CRI: 0.273, 0.687).

Maintaining sites with a continuous availability of flowering plants during bumble bee foraging periods within proximity to forests may be an effective means of sustaining diverse bumble bee communities in highly agricultural landscapes.