COMPARITIVE POLLINATION EFFECTIVENESS OF THE ALFALFA LEAFCUTTER BEE
Mark W. Hardman
Abstract
Last summer I worked for Dr. Kenna MacKenzie ofAgriculture Canada. Our objective was to determine if the alflala leafcutter bee was as effective as the honey be in pollinating hybrid seed canola. Canola fields have alternating strips of male fertile plants (the pollen source) and seed parents that must receive pollen in order to produce hybrid seeds. Our study site was a 10 hectare
field near Great Village, Nova Scotia. Honeybee hives were placed on the northern edge of the field. Shelters of alfalfa leafcutter bees were placed to the south and east. We followed bees that flew from one strip of plants to the next. Leafcutter bees crossed more often and visited more flowers than did honeybees.Before bloom we covered flowers of male-sterile plants with sacs of gauze to prevent bee pollination. At bloom we removed sacs and allowed bees to visit the flowers. Afterwards we examined stigmas under the microscope. Leafcutter bees deposited about 20% more pollen than honey bees. Both species deposited at least some pollen on most of the flowers they visited. We also measured performance of populations of bees.
Leafcutter bees caused more pollen to be deposited on stigmas of seed parent but yields of hybrid seed canola were similar in the leafcutter and honey bee zones of the field. We conclude that leafcutter bees are just as effective as honey bees in pollinating hybrid seed canola.
