Report on an Ecological Survey of Terrestrial Insect Communities in the AOSERP Study Area

Insect communities were sampled in 12 sites representative of major vegetation types in the study area of the Alberta Oil Sands Environmental Research Program (AOSERP). Insect biomass in 1978 averaged 8.2 kg ha-2 (oven dry weight), ranging from 2.8 kg (jack pine site) to 31.1 kg (fen site). In 1979, average biomass per site was 5.9 kg ha-2, ranging from 0.9 kg (disturbed site) to 20.9 kg (fen). Most insects were soil dwellers as only 1.6 to 8% of biomass was collected on foliage. Diptera larvae dominated soil collections. Ants (Hymenoptera, Formicidae) at most sites contributed heavily to the biomass total. Coleoptera and Lepidoptera were the third and fourth ranked contributors to biomass totals. Members of 261 insect families were found in the study area, of which 220 were collected in this survey. A collection of butterflies yielded 51 species, making a total 55 species known from the area. Representatives of 80 species of carabid beetles were collected, and the total carabid fauna of the AOSERP vicinity was found to be 139 species. Insect damage surveys showed great variation in the rates of insect attack on dominant plant species. Dogwood leaves bore the greatest frequency of insect scars (84 to 100%), while aspen leaves had the most leaf area •removed (1.4.7%). Few deciduous tree stems bore damage, but gall and bud damage were common on spruce. Insects caused little crown mortality. Trophic structure analysis showed that herbivores comprised the largest insect group. Carnivores, which were mostly entomophagous, were over-represented in quantitative samples due to their activity. The saprovore food chain allows protein concentration by microbes which are then consumed by saprovore animals.