MAN AND INSECTS: THE INFLUENCE OF HUMAN SETTLEMENT ON THE INSECT FAUNA OF CANADA

Abstract Because little is known of the pre-settlement insect fauna of Canada it is now almost impossible to assess all of the changes that have been caused by settlement. For most of the time that has elapsed since colonization began, settlements have been small and scattered, and land use has been non-intensive. Many refuges for native insects persisted until very recently, and many still persist but are diminishing. Thus probably few aboriginal species have been driven to extinction. Many ruderal and cultivated plants accompanied settlers from Europe and Asia. Some of these provide an expanded food supply for a few native insects and these have expanded their numbers and ranges. Other native insects have been displaced and diminished by depletion of forests and planting of crops. Exotic plants are inevitably accompanied by exotic insects and Canada has provided a hospitable home for a multitude of exotic insects. Over 300 species have been deliberately introduced for biological control. Once established in a colonial environment, the exotic origins of immigrant species are difficult to detect. Seven criteria for detecting exotic insect populations are suggested. The impacts of settlement on the principal geographic regions of Canada and their probable influence on insect faunas are briefly discussed. It is concluded that the insect fauna of Canada has been greatly enhanced by settlement.