Microhabitat Specificity of Macraeanthorhynchus ingens (Acanthocephala: Oligacanthorhynchidae) in the Raccoon {Procyon lotor)

摘要

Microhabitat specificity of Macracanthorhynchus ingens (Acanthocephala: Oligacanthorhynchidae) in the small intestine of raccoons {Procyon lotor) was investigated. Twenty-nine of 43 raccoons necropsied from Ossabaw Island, Georgia, U.S.A., were infected with 1-767 M. ingens. Macracanthorhynchus ingens occurred in the anterior 19 of 20 intestinal segments; however, over 71% of 1,481 total worms collected occurred in segments 4-9 of raccoon intestines. Worm location did not differ between sexes, among size classes, or between reproductive states (gravid vs. nongravid). Levin's standardized niche breadths for individual infrapopulations were significantly smaller than niche breadths calculated from a null model assuming random site selection. Observed niche breadths reached an asymptote at between 25 and 50 worms/raccoon. In addition, worms were observed attached to each other in segments 5-10 of the most heavily infected raccoon. These data suggest that M. ingens exhibits preferential site selection and that roughly the second quarter of the intestine encompasses the preferred habitat of M. ingens in raccoons.