Patterns of bee biodiversity across commercial New York apple orchards

With steady declines in the number of managed honey bee colonies across the United States over the past 50 years and with recent reports of catastrophic losses of honey bee colonies due to colony collapse disorder (CCD) in some regions, it is increasingly important that we examine the role of native bees in crop pollination. Here we report results of a 4-year study of native bee diversity in New York state apple orchards that reveals a surprising diversity of native bee species. Across the 25 orchards systematically surveyed, we found over 80 native bees species actively visiting apple blossoms during the period of apple bloom. Many of these species appear to be effective apple pollinators, especially members of the genera Andrena (primarily Melandrena), Colletes, Osmia, and Bombus. There was substantial variation among orchards in both the number of bee species and the abundance of individual bees. While at some orchards we found as few as 15 bee species, at others we found over 40 species. We examine the interactions between orchard size, surrounding landscape, and management practices on native bee diversity. In many orchards, native bees outnumber honeybees, indicating that native bees are likely playing an economically important role in apple pollination.