Bumble bee (Bombus impatiens) pollination of greenhouse tomatoes

Bumble bee (Bombus impatiens Cresson) pollination of commercial greenhouse tomatoes has become common in Ontario, but little research has been done on this system. The purpose of this study was to address problems associated with bumble bee pollination of greenhouse tomatoes, such as loss of bees, low levels of bee activity, inadequate levels of pollination and poor tomato quality. Separate experiments examined relationships among, (1) bee loss and activity, and greenhouse temperature and plastic type; (2) bee activity and pollination; and (3) pollination level and tomato quality. The degree of anther cone bruising resulting from buzz pollination by bumble bees was categorized into levels of pollination in commercial greenhouses and in laboratory settings. Activity was 94% greater and colony sizes were 111% greater under UV transmitting plastics than in commercial greenhouses with plastic that transmitted low levels of UV. Bee activity was weakly correlated with internal greenhouse temperature (r2 = 0.18). Pollination decreased with distance from colonies. Tomato quality improved with greater pollination in a diminishing returns relationship.