3 Overwintering management of Osmia lignaria JESO Volume 139, 2008 WINTER MANAGEMENT OPTIONS FOR THE ORCHARD POLLINATOR OSMIA LIGNARIA SAY (HYMENOPTERA: MEGACHILIDAE) IN NOVA SCOTIA C. S. SHEFFIELD 1 , S. M. WESTBY 2 , P. G. KEVAN 3 , R. F. SMITH 2 Department of Biology, York University 4700 Keele St., Toronto, Ontario, Canada M3J 1P3 email: corys@yorku.ca Abstract J. ent. Soc. Ont. 139: 3–18 The Blue Orchard Bee, Osmia lignaria Say, a commercially available solitary bee, was recently introduced into the Annapolis Valley of Nova Scotia for assessment as a manageable pollinator of apple. An important component of this assessment was to investigate options for wintering this species as few apple growers have storage facilities suitable for the recommended wintering practices. Speciically, winter survival under ambient outside, albeit sheltered conditions was compared to wintering bees in controlled environmental chambers at 4°C. In addition, a comparison of survival was made between bees from two populations; one introduced into Nova Scotia the previous year and reared for a complete generation versus one reared in Utah and imported to Nova Scotia as dormant un-emerged adults. Populations wintered outside fared slightly but signiicantly better than those wintered inside, but each location proved suitable for wintering. Bees from both populations had high survival (as measured by emergence from natal cocoons), but rates were signiicantly greater in bees reared in Nova Scotia for one year. Overall, bees from both populations proved suitably cold hardy for wintering in Nova Scotia, as evidenced by both high rates of survival and by enhanced supercooling capacity. Wintering bees in controlled conditions offers the advantages of predictable climate, and controlled synchrony of emergence with crop lowering. However, access to and/or lack of climate controlled facilities may be a limiting factor in adopting this species for commercial use in the province. This study thus provides evidence that bees wintered outside have natural emergence coinciding favourably with apple lowering, and that placing nests in sheltered outdoor environments in Nova Scotia provides an affordable and safe approach for wintering O. lignaria populations for apple pollination. Published November 2008 1 Author to whom all correspondence should be addressed. 2 Agriculture and Agri-Food Canada, 32 Main St., Kentville, NS, B4N 1J5 3 Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1