Evaluating commercially-reared bumble bees for pollination of highbush blueberry

As with most bee-pollinated crops, growers of commercial highbush blueberry (Vaccinium corymbosum L.) typically rent honey bee colonies because the native bee fauna is thought to be unpredictable or insufficient for commercial acreage. However, honey bees are not ideally suited to northern climates during spring and are not well adapted to pollinate blueberry flowers. Consequently, other managed pollinators are being sought to pollinate this crop. One such pollinator is the native bumble bee, Bombus impatiens Cresson. Bumble bees are well adapted to pollinate blueberry because of their ability to sonicate or buzz pollinate flowers. They also are known to be active during cooler, more inclement weather than honey bees. Commercially reared bumble bees have been used successfully in greenhouse pollination, but less is known about their utility in open field settings. Here we report on the results of two years of field studies of B. impatiens in which we evaluated their performance for pollination of highbush blueberry. Experiments were conducted to compare fruit set and yield in fields stocked with bumble bees or honey bees. Pollen collected from bumble bee workers returning to colonies set at different distances away from an isolated field were also used to determine the foraging range of B. impatiens to this crop and the fidelity of this species to blueberry.