Woodland bee diversity in the Mid-Atlantic

Delaney, Deborah A.Native bees are vital to both agricultural and natural systems for the valuable pollination services they provide. Honey bee colony losses have raised concerns over whether native pollinators are also at risk, and declines have been recorded in several species. However, the population status of most bee species remains unknown due to a lack of both historic and recent survey data, making it difficult to judge how bees are responding to habitat loss and other anthropogenic disturbances. The bulk of data has been collected in agricultural systems or open habitats, with forested areas rarely being surveyed for native bees. ☐ In an effort to establish a baseline dataset for monitoring of forest bee communities, we surveyed vernal bees from woodlands across the Mid-Atlantic. We found a community dominated by solitary, ground nesting species, primarily in the genera Andrena, Nomada, Osmia and Lasioglossum. One new state record was collected in Maryland, Andrena rufosignata. Additionally, several species previously considered uncommon in the region were prevalent in the forest community, suggesting that sampling bias towards open habitats has resulted in under-sampling of bees closely associated with woodlands. ☐ Sites differed in density of bees and species composition, but a typical list of forest bees emerged from our surveys. The most familiar faces in these communities are a few common Andrena species, Andrena carlini and Andrena perplexa, as well as the oligolectic Spring Beauty bee, Andrena erigeniae. The nest parasites of Andrena, species in the genus Nomada, are also usually present, as are a group of Lasioglossum species that seem to be associated with woodlands. Many of these forest dwelling species appear to be resilient to urban development; even our smallest forest fragments surrounded by dense urban development support many of these woodland associated bee species. ☐ The results of our occupancy and abundance modeling were also promising for the conservation of bees in urban areas, with development rarely being a major landscape predictor. Instead, most species seem to prefer bottomland woodlands with some penetration of wetlands or open water over extensive closed canopy forest. These wetland and riparian areas create more open canopy forests that are likely to be rich in the vernal forbs and flowering woody plants wild bees forage on. ☐ The results of our study offer a closer look into the forest bee community, how that community shifts across the landscape, and how species differ in their response to surrounding landcover. Our dataset can serve as a baseline for future monitoring of bees throughout the region, and the patterns that emerged will hopefully spur further investigation toward understanding wild pollinator ecology and population dynamicsUniversity of Delaware, Department of Entomology and Wildlife EcologyM.S