Tritrophic Associations between Spider Wasps (Hymenoptera: Pompilidae), Wolf Spiders (Araneae: Lycosidae), and Grasshoppers (Orthoptera: Acrididae) on Mixedgrass Prairie

摘要

Tritrophic associations between spider wasps, spiders, and grasshoppers were studied at 28 mixedgrass prairie sites in northwestern South Dakota. The multivariate ordination technique, detrended correspondence analysis (DCA), and correlation analysis were used to assess spatial change in the community structure of spider wasps collected with malaise traps and to define underlying ecological gradients associated with community change. Results indicated that community composition of spider wasps changed along gradients defined partly by activity of the ground-dwelling lycosid, Schizocosa mccooki (Montgomery), and percentage of sand in soils. Distinct habitat segregation was found for two of the three dominant species of spider wasps, Cryptocheilus attenuatum Banks and C. terminatum (Say). Factor analysis of species at three trophic levels indicated associations between numbers of the spider wasp Pompilus apicatus Provancher, S. mccooki, and the obligate grass-feeding grasshopper Trachyrhachys kiowa (Thomas). All three species were abundant in habitats with high grass coverage.