Pollination by Apis and non-Apis bees in North Carolina blueberry agroecosystems

Managed honey bees (Apis mellifera) provide essential pollination services for many commercial crops. However, wild (non-Apis) bees may contribute significant ecosystem services in the absence of Apis bees or by complementing, and potentially enhancing, pollination by honey bees. In blueberry (Vaccinium spp.), the long corollas and narrow openings of flowers may hinder visitation by relatively short-tongued Apis bees. However, longer-tongued native bees capable of sonication (e.g. southeastern blueberry bees, Habropoda laboriosa) may provide more efficient pollination. This study sought to determine the role of species richness, abundance, and diversity in pollination in the southeast blueberry agroecosystem. Preliminary assessments in spring 2009 established five functional groups of blueberry pollinators: A. mellifera, Bombus spp., H. laboriosa, small native bees (belonging to Andrenidae, Halictidae, and Megachilidae), and X. virginica. For the first of three field seasons, pollination data was collected at seven plantings across North Carolina. The study sites were chosen to reflect a diversity of management strategies, farm sizes, geographic regions, and blueberry varieties. At individual flowers, caging-studies were used to determine single-visit pollination efficiencies of each functional group. Diversity was sampled using pan-traps, blue-vane traps, and timed transect walks. The results of this study could have implications for the management of pollination services in blueberry and other pollinator-dependent agroecosystems. Ultimately, a diversity of pollinator species (including highly social generalists and solitary specialists) may prove to benefit crop pollination more than any bee species on its own.