Recent Studies in Canada of Crop Pollintion by Insects

A. P. Arnason


In Canada more than half a million hectares are used for the production of crops that require (or at least partly depend on) insect pollination if they are to produce near mximum yeilds of seed or fruit that other conditions permit. The chief native pollinators are wild bees: mainly leaf-cutter bees, bumble bees, and in some crops and areas andrenids and halictids. Their numbers vary considerably from year to year and from feild to feild, so that seed or fruit set varies unpredictably. Also, in districts where most of the land is under cultivation, the numbers of wild bees tend to fall to such low levels that the pollinating force is always inadequate. Fortunately, most fruit crops requiring pollination by insects and forage crop legumes (with the exception of alfalfa and to some degree red clover) are readily pollinated by honeybees, which can be provided in numbers that will result in maximum production of fruit or seed. Under Canadian conditions of cool weather high incidence of other attractive bloom, honeybees have proved of little value in seed production. Special management practices are required to ensure that they will forage on red clover and set worthwhile crops of seed from it. No methods of getting high pollination of alfalfa by honeybees are available. In general, growers have not yet adopted practices of management for eithe wild bees or honeybees that ill produce maximum production of these crops; and with crops like alfalfa and low-brush blueberries reliable means of maintaining adequate forces of insect pollinators have yet to be fully developed.