The impact of forest harvesting on a boreal parasitoid (Hymenoptera: Ichneumonidae) community

Ichneumonidae are parasitoids of other arthropods, particularly among the Lepidoptera and Symphyta. As such, they play a large role in the regulation of potential pest species, and may be an important driver of diversity patterns in other organisms. However because of their highly specialized life histories and high trophic level they may also be particularly vulnerable to ecological disturbances. This study was conducted in 2008 at the EMEND (Ecosystem Management Emulating Natural Disturbance) research site, approximately 90 km northwest of Peace River, Alberta. I collected ichneumonids from four harvesting treatments (uncut, 50% retention, 20% retention, clearcut), 8 years post-harvest, in deciduous-dominated stands, to assess the impact of variable retention harvesting on the ichneumonid community. A total of 47,710 ichneumonids (68 individuals/trap/day) from 23 subfamilies were counted. Three subfamilies (Pimplinae, Poemeniinae, and Rhyssinae) were further identified to species, with a total of 2336 specimens in 55 species. Species-richness was highest in the clearcut sites, but did not differ among the other treatments. Four subfamilies and one pimpline species were significant indicators of the uncut stands. The overall community patterns and the challenges of studying parasitoids in a management framework are discussed.