POTENTIAL OF THE ALFALFA LEAFCUTTER BEE, MEGACHILE-ROTUNDATA (F) (HYM., MEGACHILIDAE) TO POLLINATE HAIRY AND WINTER VETCHES (VICIA SPP.)

The effectiveness of the alfalfa leafcutter bee, Megachile rotundata ( F.), as a potential pollinator of winter (woollypod) vetch, Vicia dasy carpa Ten., and hairy vetch, Vicia villosa Roth., was evaluated over a 3-year period. Populations of the most important pollinator of the cr op, the honey bee, Apis mellifera L. continue to decrease in North Ame rica, thus there is a need to evaluate alternate pollinators so that s eed growers can optimize their choice of pollinator. Treatments consis ted of plants caged to exclude all pollinators, plants caged with leaf cutter bees, and plants exposed to resident pollinators including alfa lfa leafcutter bees. These Vetches were self-sterile and produced very little seed when bees were excluded. Pods and seeds per raceme, seeds per pod, percentage seed set and yield were significantly higher for plants of both species exposed to resident pollinators compared to pla nts caged with leafcutter bees. Significant differences between the tw o treatments indicate that the alfalfa leafcutter bee would not serve as an effective pollinator for these vetches. However, if insufficient populations of honey bees or resident native bees exist in an area, o nly then may leafcutter bees have a place in commercial seed productio n. Several species of bumble bee were the main pollinator of these cro ps in Alberta, Canada. The seed production of these vetches indicates they may have potential as new legume crops for western Canada.