Copyedited by: OUP Annals of the Entomological Society of America, XX(X), 2018, 1–6 doi: 10.1093/aesa/say028 Research Research Pollen Use by Osmia lignaria (Hymenoptera: Megachilidae) in Highbush Blueberry Fields Mario S. Pinilla-Gallego1,2,4 and Rufus Isaacs1,3 1Department of Entomology, Michigan State University, 578 Wilson Road, East Lansing, MI 48824, 2Applied Ecology Department, North Carolina State University, Campus Box 7617, 100 Brooks Avenue, Raleigh, NC 27607-7150, 3Ecology, Evolutionary Biology, and Behavior Program, Michigan State University, 103 Giltner Hall, 293 Farm Lane, East Lansing, MI 48824, 4Corresponding author, e-mail:
[email protected] Subject Editor: Allen Szalanski Received 8 May 2018; Editorial decision 14 July 2018 Abstract The blue orchard bee, Osmia lignaria (Say) (Hymenoptera: Megachilidae), is an alternative managed pollinator of rosaceous tree-crops, and potentially could be used for blueberry (Ericaceae) pollination. However, the floral preferences of this species for other types of flowers could prevent them from visiting blueberry flowers when alternative forage is available. To evaluate O. lignaria suitability for pollination of commercial blueberries in Michigan, we identified the main pollen sources in scopal loads and brood provisions, and determined the contribution of blueberry pollen to pollen collected by females nesting inside or at the border of a large blueberry field. Across two bloom seasons, we found that blueberry pollen was not the most abundant pollen type in either the scopal loads (≈6%) or the brood provisions (13–20%). Black cherry (Prunus serotina, Rosaceae), white clover (Trifolium repens, Fabaceae), and red clover (Trifolium pratese, Fabaceae) were the most abundant pollen types in the brood provisions.