Factors potentially limiting colony growth, foraging effort, and pollination efficiency of bumble bees in commercial tomato greenhouses

I examined several factors potentially limiting bumble bee colony population growth in commercial tomato greenhouses. I investigated whether bumble bees are obtaining adequate nutrition and growing to their maximum population size in commercial tomato greenhouses. As well, I compared Bombus occidentalis Greene and Bombus impatiens Cresson as pollinators and examined inter-specific competition between the two species. I also investigated how often bumble bees forage outside greenhouses and studied the effects of the protozoan parasite Nosema bombi and its treatment fumagillin in B. occidentalis colonies.;B. occidentalis colonies obtain adequate nutrition in commercial tomato greenhouses, but there is high loss of workers so colonies are not growing to their maximum population size. B. impatiens colonies are more effective pollinators than B. occidentalis colonies likely because they grow to larger population sizes and forage more frequently. (Abstract shortened by UMI.)...