Foraging activity and pollination by managed colonies of Bombus impatiens (Hymenoptera: Apidae) in highbush blueberry (Vaccinium corymbosum)

Highbush blueberry (Vaccinium corymbosum) requires insect-mediated pollination to produce marketable fruit. Introduction of honey bee colonies to fields during bloom is the primary management strategy for pollination, but colonies of the common eastern bumble bee (Bombus impatiens) are also available as a supplementary or replacement pollinator. Combining honey bees and bumble bees is expected to provide benefits during variable weather conditions, thereby minimizing pollen limitation and ensuring maximal crop yield. In a two-year study, blueberry pollination was compared between fields stocked only with honey bees and fields stocked with both honey bees and managed bumble bees. Fruit set, berry weight and seed set were measured from focal bushes, and the activity of bumble bee colonies was measured at the hive and on blueberry flowers. Furthermore, composition of pollen loads and hive growth parameters were analyzed to determine bumble bee foraging fidelity to the crop and hive success throughout blueberry bloom. The relative benefits of the two pollination management strategies for commercial blueberry production will be discussed.