Management of the Alfalfa Leafcutting Bee, Megachile rotundata (Hymenoptera: Megachilidae), for Pollination of Wild Lowbush Blueberry

The alfalfa leafcutting bee (Megachile rotundata F.) was investigated as an alternative pollinator to the honey bee (Apis mellifera L.) of wild lowbush blueberry (Vaccinium angustifolium Ait.). Pollinator effectiveness and stocking density were determined by examining the effect of M. rotundata on fruit set in relation to foraging distance from the nesting shelter. A significant relationship existed between distance from individual nesting shelters and percent fruit set for nine of 15 shelters. Megachile rotundata improved fruit set by as much as 30% over background pollination (pollination provided by honey bees and native bees). A recommended stocking density of 49,420 bees/ha was estimated. Fruit set was significantly higher in${\rm m}^{2}$plots visited by migratory M. rotundata (forage provided before blueberry bloom) than in plots visited by nonmigratory M. rotundata (no forage provided before bloom). Overall reproductive ratio was less than 0.2 loose cells produced to loose cells incubated. The alfalfa leafcutting bee can be a suitable and cost-effective alternative to the honey bee for pollination of V. angustifolium, but will probably need to be purchased annually.