Effects of Farmland and Seasonal Phenology on Wild Bees in Blueberry Orchards

A diverse wild bee fauna can greatly enhance crop yields, but on-going declines in populations of global pollinators may jeopardize food security in the future. Diversity of wild bees in agricultural settings is shaped by a multitude of factors including farming practice, farm size and surrounding land-use type. However, these factors may vary greatly across regions and agricultural systems, making broad generalizations difficult. Therefore. there is a critical need to describe communities of wild bees in relation to farm size and adjacent land-use type. We collected wild bees using pan trapping and sweep netting throughout the summer season. We compared wild bees among 3 blueberry orchards of varying sizes and percentage of adjacent forest margins. We used complementary metrics to characterize the bee fauna at the species and community level including phylogenetic diversity, functional traits, and indicator species. We found that bee diversity and abundance was highest at the smaller orchard, which had more adjacent forest. A particularly depauperate bee fauna was found at the 2 larger orchards with less adjacent forest. Here, the blueberry-associated bee communities differed markedly among the 3 surveyed orchards. The large and medium orchards harbored clustered communities and had almost no parasitic bees. Our results support the notion that environmental filtering by larger agricultural landscapes act on species and functional traits and can lead to community homogenization. Our study provides the first-of-its-kind data for wild bees in New Hampshire's blueberry-orchards. These results can inform farmers about the diversity and pollination services of wild bees and guide implementation of improved management and conservation strategies for the preservation of wild bees in their orchards.