Effects of land-use change on the foraging preferences of a purported specialist bee (Habropoda laboriosa)

Our growing human population requires increasing access to agricultural and urban habitat leading to rapid land-use change. Pollinator dietary specialists may be more sensitive to land-use changes and subsequent changes in plant communities than their generalist counterparts. The southeastern blueberry bee, Habropoda laboriosa, is a purported oligolege of blueberry and related plants in the Vaccinium genus. Habropoda laboriosa presents and ideal system for examining the effects of land-use change and plant domestication on bee foraging preferences because H. laboriosa and wild and cultivated Vaccinium spp. are commonly found in a variety of habitat types. To assess the foraging preferences of H. laboriosa, we collected over 500 H. laboriosa from 21 sites including 7 urban, 7 agricultural (blueberry farms), and 7 native habitats (flatwoods) and quantified the proportion of different pollen types in each bee pollen load. Additionally, we assessed inflorescence richness and abundance at each site. We hypothesized that H. laboriosa would select for Vaccinium or closely related plants in the Ericaceae family, as shown by a high proportion of Vaccinium or related pollen relative to the abundance of those plants in the landscape. We found that pollen loads contained pollen from a diversity of plants and did not contain proportionally more Vaccinium pollen than was available in the landscape. Despite apparent specialist behaviors, our results suggest H. laboriosa is utilizing the most abundant plants in the landscape rather than specializing on Vaccinium, indicating that it may be resilient to land-use change and subsequent changes in plant community composition.