Diversity of parasitic Hymenoptera (Ichneumonidae: Campopleginae and Ichneumoninae) in Great Smoky Mountains National Park and eastern north American forests
Skillen, Elizabeth Lockard
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I examined species richness and composition of Campopleginae and Ichneumoninae (Hymenoptera: Ichneumonidae) parasitoids in cut and uncut forests and before and after fire in Great Smoky Mountains National Park, Tennessee (GSMNP). I also compared alpha and beta diversity along a latitudinal gradient in Eastern North America with sites in Ontario, Maryland, Georgia, and Florida. Between 1997- 2000, I ran insect Malaise traps at 6 sites in two habitats in GSMNP. Sites include 2 old-growth mesic coves (Porters Creek and Ramsay Cascades), 2 second-growth mesic coves (Meigs Post Prong and Fish Camp Prong) and 2 xeric ridges (Lynn Hollow East and West) in GSMNP. I identified 307 species (9,716 individuals): 165 campoplegine species (3,273 individuals) and a minimum of 142 ichneumonine species (6,443 individuals) from 6 sites in GSMNP. The results show the importance of habitat differences when examining ichneumonid species richness at landscape scales. I report higher richness for both subfamilies combined in the xeric ridge sites (Lynn Hollow West (114) and Lynn Hollow East (112)) than previously reported peaks at mid-latitudes, in Maryland (103), and lower than Maryland for the two cove sites (Porters Creek, 90 and Ramsay Cascades, 88). These subfamilies appear to have largely recovered 70+ years after clear-cutting, yet Campopleginae may be more susceptible to logging disturbance. Campopleginae had higher species richness in old-growth coves and a 66% overlap in species composition between previously cut and uncut coves. Ichneumoninae had similar richness in both cut and uncut coves and a 75% overlap in species composition. Parasitoid relative abundance declines one year post fire, but community composition appears the same. Campopleginae parasitoids may be more susceptible to fire disturbance, one year post fire. Eastern North American Campopleginae and Ichneumoninae, in most cases, appear to have a consistent pattern of decay in similarity with distance. Altitude may be a confounding factor. In general, common species represent a higher percentage of species richness at distant sites than do rare species. Stratified sampling methods are superior to sampling at one location or at one time, and undisturbed habitats contain more species of specialized groups like the Campopleginae.