Relationships Between Flowering Plants and Four Species Ofbombus(hymenoptera: Apidae) in Southern Ontario

An attraction to certain plant species by Bombus terricola , B . bimaculatus , B . perplexus , and B . ternarius was observed. The gathering of pollen was observed as a behavioural act distinct from nectar gathering. Pollen analyses indicated that pollen collectors restricted their activities to a small number of plant species. These bees’ life histories and flower preferences made them potentially effective pollinators of early-flowering economic crops, Ribes spp., and Pyrus Malus in particular, and of common weeds such as Solanum Dulcamara and Hypericum perforatum . The same reasons prevented them from being important in the pollination of Trifolium pratense and Medicago sativa .