LB 34-282 - Forest-associated bees are important pollinators of spring-blooming crops

The yields of spring-blooming fruit crops are frequently limited by pollinator visitation, likely due in part to declines in pollinator abundance, in addition to inclement spring weather conditions that limit pollinator activity. To support spring crop pollination, wild pollinator management should be tailored to wild spring-flying bees, which are known to enhance fruit quality and quantity and are better adapted to cool, windy spring weather than managed honey bees. A majority of spring-flying bee species in eastern North America are dependent on deciduous forest habitat, yet current wild pollinator management practices exclude these bees by focusing on open meadow habitats and on plants that bloom in the summer, after the flight seasons of spring-flying, forest-associated bees have ended. We evaluated the extent to which wild bees that act as important pollinators of spring-blooming crops are forest-associated. We cross-referenced known habitat associations with 11 published datasets comprising 19,162 flower visitation records of 227 bee species netted from 5 spring-blooming crop species in eastern North America—apple, highbush blueberry, lowbush blueberry, tart cherry, and strawberry. We defined important wild bee pollinators for each dataset as the minimum species set cumulatively accounting for 80% of recorded wild bee visits to crop flowers.Of 71 wild bee species identified as important spring crop pollinators, habitat associations were available for 46. Of these 46, 18 were forest specialists and 13 were habitat generalists that frequently use forests. Thus, among species with known habitat associations, 67% of important wild bee pollinators of spring crops were forest-associated. The best-represented genera among the forest-associated spring crop pollinators were Andrena, Lasioglossum, and Bombus. These results highlight the importance of forest-associated bees for spring crop pollination and suggest that forests could be managed to promote spring pollinators. However, there are currently no management guidelines for forest-associated bees because it is unclear what factors influence the quality of a forest as habitat for forest bees. Future research on (1) the variables that drive bee abundance and diversity in forests and (2) the response of forest bee communities to forest management strategies will be key for understanding how forests adjacent to crop fields can be managed to increase yields.