Nearby forest habitat increase wild bee diversity in managed blueberry fields

Global declines in managed honey bee populations have been a major concern for the agricultural sector. Similarly, continued habitat fragmentation and degradation of natural and semi-natural habitats have been identified as a major threat for wild bee communities. In Canada, wild bees and managed honey bees both pollinate blueberries (Vaccinium spp.), which is the largest fruit commodity and accounts for a market value of over $250 million per year. I assessed whether the amount of forest land cover surrounding highbush blueberry fields affects the diversity of wild bee pollinators. Specifically, I sampled wild bee communities in 18 blueberry fields during the blooming period in Monteregie, Quebec, Canada. Sampling consisted of placing pan trap triplets and direct observation of flower visitations on blueberry bushes. I also quantified the surface area representing natural, semi-natural, and anthropogenic landscape cover in a radius of 500m, 1000m, and 2000m around each field. Then I related wild bee abundance and richness to forest land cover proportion. The proportion of forest land cover varied along different scales from 0.00% to 50.8% at 500m radius and from 0.17% to 62% at 2000m radius. Wild bee abundance and richness were positively related to the proportion of the forest habitat adjacent to the crop field. Moreover, the strength of these relationships increased with spatial scale. By understanding how the nearby natural habitat benefits wild bee diversity in highbush blueberry fields and, ultimately, pollination services, conservation efforts can focus on land cover features to help halt the decline in bee diversity.