Abstract
Analysis of host selection in 57 spider wasp species and 1 species-complex from the eastern Great Lakes Region revealed new ecological, taxonomic, and size relationships, supplementing and updating information for the family Pompilidae in the Catalog of Hymenoptera in America North of Mexico (Krombein 1979). The spider wasps preyed on large, moderate-size, or somewhat small spiders, according to their own size, and disregarded very small and tiny spiders when stocking a nest cell with a single host spider and wasp's egg. Large pompilid species preyed mainly on adult, penultimate, and subadult female spiders, and small spider wasp species captured mostly immature/juvenile spiders. Three different-sized spider wasp species inhabiting sandy soils-Anoplius cleora (large), A. apiculatus (medium-size), and Priocnemis cornica (small)-exclusively or frequently captured different sizes, sexes, and stages of the shoreline sand spider Arctosa littoralis (Lycosidae). Anoplius nigritus, A. semicinctus, and A. cylindricus, living in some of the same sandy areas, stung, paralyzed and stocked a large or small (A. cylindricus) burrow-inhabiting wolf spider (Lycosidae), Geolycosa wrighti, in the spider's own burrow. Caliadurgus fasciatellus, Agenioideus humilis, Episyron biguttatus, E. quinquenotatus, and Poecilopompilus interruptus preyed on different sizes, sexes, and stages of several common orb-weaver species (Araneidae) according to their own size. Two related, strongly polyphagous spider wasp species of the same size and color-Anoplius splendens, a psammophile, and A. marginatus species-complex, a group of 5 species found in sandy, gravelly and loamy areas and difficult to distinguish from one another in female form-provisioned nests with similar sizes, sexes, and stages of many of the same host spider species. Anoplius semirufus, a slightly smaller pompilid species cohabiting sandy areas with species in the A. marginatus species-complex and A. splendens, was rather oligophagous in host selection and provisioned nests mainly with small and moderate-size cursorial-hunting wolf spiders of several genera. Four large spider wasp species from abandoned, overgrown fields and woodland edges-Entypus unifasciatus, Tachypompilus ferrugineus, Anoplius aethiops, and A. atrox-preyed on large, mainly adult female fishing spiders (Pisauridae) and/or large wolf spiders (A. aethiops). Four different-sized, polyphagous, deciduous woodland pompilid species-Priocnemis minorata, P. germana, P. scitula, and Anoplius virginiensis-partitioned different sizes, sexes, and stages of common woodland cursorial-hunting and retreat-dwelling host spiders of several families, especially the hacklemesh-weaver spider Callobius bennetti (Amaurobiidae), according to their own size. Paired and 3-way statistical analyses of host selection in species of Auplopus (mellipes, nigrellus), Anoplius s. str. (imbellis, ithaca), Ammosphex (angularis, michiganensis), Arachnospila (arctus, scelestus), and Aporinellus (completus, medianus, taeniatus) disclosed significant ecological and predatory differences. Species of Pompilidae were associated with specific natural communities at Presque Isle State Park, Erie County, PA; Selkirk Shores State Park, Oswego County, NY; and Southwick Beach State Park, Jefferson County, NY.