Bumblebee workers are efficient pollinators. However, despite their flower visits and less
intense grooming the role of males as pollen vectors is largely unexplored. We compared the quantity
and diversity of pollen on the bodies (pollination-active pollen) of free-foraging workers and males of
two bumblebee species (Bombus lapidarius and Bombus terrestris) to assess their pollination potential.
In both species, males exhibit worker-like flower constancy, but differ significantly from workers in the
predominantly collected pollen types. Mean pollen loads of approximately 10,000 grains/individual
suggest that males can contribute to the colony pollination service. Bumblebee males add to the diversity
of pollinators, associated to increased crop pollination and facilitate pollen flow in specific ways,
worthwhile further investigation.