Cases of Naturally-Occurring Biological Control in Canada

Abstract

There are, in Canada, many documented reports of naturally-occurring biological control of arthropod pests. The examples we have chosen are a few recent cases from forest and orchard entomology. Changes in densities of apple pest populations, initiated through destruction of natural enemies by spray chemicals, have been under investigation in Nova Scotia since 1943, and of peach pests in Ontario since 1946; intensive ecological studies on forest pest populations began about the same time in New Brunswick. We have selected from the many examples available the native black-headed budworm, Acleris variana (Fern.), found in forests; and European red mite, Panonychus ulmi (Koch), a lecanium scale, Lecanium coryli (L.), and codling moth, Laspeyresia [=Carpocapsa] pomonella (L.), commonly found as pests in orchards. These orchard pests apparently have reached North America from Europe since the apple was introduced early in the 17th century. They are well established, widely distributed species.