Movements of male and worker bumblebees on and between flowers

Male bumblebees leave the nest after hatching, but workers bring pollen and nectar to the nest during their entire life. We thus predicted that males and workers differ in foraging activity and long-distance movements, and thereby contribute differently to pollination. We analysed flower-handling efficiency, pollinia-carrying capacity, movement patterns between patches of flowers, and daily activity patterns of Bombus terricola and B. vagans individuals while foraging on milkweed Asclepias syriaca, and goldenrod Solidago spp. in Maine, USA and followed Bombus pratorum foraging on fireweed Epilobium angustifolium in Dalsland, Sweden. Males and workers differed in flower handling only on Solidago, where males visited more flowers per stalk and fewer inflorescences per minute than workers. Both males and workers carried similar numbers of milkweed pollinaria for similar periods and flew similar distances between patches of flowers. However, proportionately more males foraged in the afternoon than in the morning. Thus, males forage less than workers but appear to differ little in how they forage.