Auto Scroller

Insects

Terrestrial


Overview

Insects and their relatives are found in almost every conceivable habitat, and play many roles in Canadian ecosystems. These ecological roles have led to a pervasive economic importance, though this is not always obvious because many species are small and inconspicuous. Included in the group are species that eat living plants, species that feed on decaying materials, species that prey on other invertebrates, and parasites of other insects or of vertebrates. Many insects transmit various diseases to animals, including man, and to plants. Over half of Canada's flowering plants are pollinated by insects.

Although the numbers of kinds of insects and their relatives are reduced in the North, they remain the dominant group, far exceeding all other animals in numbers of species and numbers of individuals. For example, about 4000 species live in arctic regions beyond the limit of trees. Consequently, nearly all of the characteristic natural roles of insects are fully visible, even in the high arctic.

Because of this abundance, insects are relevant to management plans for natural areas in several different ways, for example:

  • Biting flies and bot flies affect wildlife directly, especially caribou
  • Insects are a main source of food for many fish and birds
  • Insect communities and species can act as environmental indicators of environmental change
  • Some particular kinds of species are especially likely to be vulnerable to habitat change

Biting flies (the insect order Diptera) are among the most conspicuous components of the North Slope insect fauna. They belong to one of several families, including mosquitoes, black flies, biting midges (also called no-see-ums, punkies, or sand flies), and horse flies and deer flies (collectively called tabanids). Although the number of northern species is not especially large, some of the pest species may occur in vast numbers in certain places, or during certain times of year. Poor drainage due to permafrost contributes largely to the abundance of biting flies. Mosquitoes reach their peak abundance in late June or early July, though their presence is felt well into the fall. They are by far the most severe and troublesome of all the biting flies. Tabanids emerge shortly after the mosquitoes, followed in mid- to late summer by black flies. The immature stages of black flies are confined to running waters, and emergences of Simulium nigricoxum can be troublesome in the vicinity of breeding sites. Biting midges are present, but occur in much lower numbers than representatives of the other families.

The bloodsucking activities of biting flies can seriously affect humans and other warm-blooded animals. Their influence ranges from mere annoyance, to severe allergic reactions and transmission of parasitic diseases. A malaria-like disease carried by black flies, for example, is known to cause mortality in populations of great horned owls in central Yukon. The role of biting flies in disease transmission is poorly studied at northern latitudes.

Biting flies and bot flies (which parasitize living flesh) can be a major source of stress for wildlife. Caribou become terror-stricken when adult bot flies are in the vicinity, galloping to shade or water in an effort to escape. This phenomenon, termed "gadding", often spreads to the whole herd. The Canadian Wildlife Service studied the effects of mosquitoes, warble flies, and bot flies on summering caribou. The study identified specific habitats as insect relief areas, and determined that maintenance of such areas are critical for the health of the herd.

Insects are the main source of food for northern fishes. Fish such as the Arctic Grayling, Dolly Varden, and the Arctic Cisco, are dependent on aquatic and terrestrial insects to fulfill their nutritional requirements. Insects are also important for nesting birds, because their abundance and high food value support the chicks of many migrant breeding species, even those that eat mainly plant material as adults. North Slope wetlands support enormous populations of chironomids (non-biting midges) and other aquatic insects that are crucial as food for birds.

In addition to their importance in northern food chains, insects may serve as indicators of environmental change, both in the shorter term, e.g. local habitat modification, and in the longer term, e.g. potential global warming. Insects are especially valuable for biomonitoring because their great diversity involves them in ecosystems in so many different ways. In addition, as mentioned below, many individual kinds of insects on the North Slope have particular habitat requirements or live at the limit of their ranges. Monitoring vulnerable species may serve as an early warning for environmental changes in temperature and other parameters.

Parts of the North Slope that were not glaciated during the last ice age served as a refugium ("Beringia") for certain organisms. The region has been a focus of study by northern biogeographers ever since the refugium was first postulated in the 1930's. Many of the insects that survived in Beringia are endemic or restricted to the region, and many of these have particular habitat requirements or vegetation associations. As such, they are especially vulnerable to habitat degradation or perturbations. Regions of high endemicity include unglaciated limestone areas and the White Mountains. In some groups of insects, most of the endemic species are associated with dry tundra habitats.

The many roles of the diverse insects in the North make them useful in environmental conservation and management of natural resources, as well as for general and applied scientific studies. The advantages of insects for management can best be exploited if studies are carefully planned and involve specialists able to identify the species involved. Basic knowledge of the fauna is the essential prerequisite for such uses. A book on the insects of the Yukon, published by the Biological Survey of Canada (Danks and Downes 1997), is a key step in establishing credible baseline information on the Yukon, including the North Slope fauna.

Research and Monitoring

Some species of insects have been collected on the Yukon North Slope as part of a Government of Yukon project (2005 and 2006) to look for and collect rare species of plants, butterflies, birds, snails and small mammals along the coastal plain. The objective of the study is to gather some baseline inventory information that is needed to monitor the status and distribution of these species. This information is important for monitoring environmental change in the area that may be occurring because of climate change.

Community-based Information

Community-based information on insects may also be found in the reports of the annual community-based monitoring program conducted in Aklavik and neighbouring communities by the Arctic Borderlands Ecological Knowledge Co-op. http://www.taiga.net/coop/community/index.html

Related Literature and Information Sources

Danks, H.V. and J.A. Downes (Eds.), 1997. Insects of the Yukon. Biological Survey of Canada (Terrestrial Arthropods), Ottawa. 1030 pp.