Sex-biased parasitism in Skrjabingylus nasicola infection in ermine (Mustela erminea) Ermine (Mustela erminea) are trapped as legal furbearers but are not actively managed by the Wisconsin Department of Natural Resources. We are concluding a long-term parasite assessment of ermine through collection and necropsy of carcasses provided by trappers. Our aim is to better understand the host-parasite relationship between ermine and Skrjabingylus nasicola, a parasitic nematode of the nasal sinus. Specifically, we investigated sex-biased parasitism, where one sex of a host displays higher intensities (number of worms per host) than the other sex. Additionally, we wanted to investigate if size of the cranium limits the intensity of S. nasicola by limiting the size of the nasal sinuses that the adult parasites inhabit. We hypothesized that male ermine would have higher intensity infections of S. nasicola and that ermine with larger cranial volume would have higher intensities. Ermine were necropsied and S. nasicola were identified using reference specimens in the Steven Taft Parasitological Collection. Sex of ermine was determined by the presence or absence of a baculum. Cranial volume was calculated by measuring the length, width, and depth of the cranium with calipers. We used a two-way ANOVA to determine if intensity differed with sex and a simple linear regression to determine the relationship between cranial capacity and intensity. Over the last 6 years, average intensity for male ermine was 19.35 worms per host (SD = 11.60) and average intensity for female ermine was 10.69 worms per host (SD = 7.55) resulting in males having significantly higher intensities (F1, 231 = 27.571, P < 0.001). Cranial capacity was positively related to intensity (F1, 32 = 15.381, P < 0.001), suggesting that cranium size may limit intensity for S. nasicola. Ermine natural history traits such as a polygynous mating structure, difference in home range size, and sexual dimorphism likely influence sex-biased parasitism in ermine. Oral Mentors: Dr. Shelli Dubay and Dr. Todd Huspeni Consider for Judging
Matthew Buchholz Major: Wildlife Research & Managment Minor: Biology
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University of Wisconsin Stevens Point College of Natural Resources