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Tuesday, January 30 • 2:40pm - 3:00pm
SMALL MAMMALS: Sex Biased Effects on Prevalence of Parasites in Southern Flying Squirrels

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AUTHORS. Christopher N. Jacques, Western Illinois University; Shelli A. Dubay, University of Wisconsin-Stevens Point; Bridget M. Walker, University of Wisconsin-Stevens Point; Robert W. Klaver, US Geological Survey

ABSTRACT. Environmental or intrinsic characteristics that predispose hosts to parasitic infections (and particularly to co-occurrence) are not well understood, but sex and age often influence prevalence and intensity of parasitic infections in hosts. Collectively, results from previous studies suggest that intersexual differences in hormonally-mediated immunosuppression and behavior may contribute to sex biases in parasitism. Southern flying squirrels (SFS; Glaucomys volans) are small-bodied, non-hibernating, communally nesting, rodents that occur in low densities across Midwestern landscapes and frequently defecate into substrate within communal nesting cavities. Thus, SFS are ideal organisms to evaluate several hypotheses related to host-parasite relations, including how parasite co-occurrence and sex-biased parasitism in hosts concurrently affect distributions of parasites. Of 52 SFS examined for parasites, prevalence of infection for Strongyloides robustus, Coccidia, and ectoparasites was 57.7%, 44.2%, and 46.2%, respectively. We documented similar patterns of infection with SFS harboring ectoparasites, in which case individuals also were infected with S. robustus (42%) or Coccidia (31%); 38% and 40% of SFSs that did not harbor ectoparasites also tested negative for S. robustus and Coccidia, respectively. Probability of infection with S. robustus increased 27.50 (OR = 27.500, 95% CI = 5.210–45.154) and 12.67 (OR = 12.667, 95% CI = 3.016–23.189) when animals also were infected with ectoparasites or Coccidia, respectively. We collected 107 ectoparasites from 52 squirrels, of which the morphology of 99 (92.5%) was consistent with the flea species Orchopeas howardi. Males were significantly more parasitized than females, and small males were more parasitized than large males. Because SFS exhibit plasticity in sexual dimorphism, sex differences in parasite loads may be attributable to immunosuppressive qualities of testosterone. Ectoparasite loads also may negatively influence body condition, and juvenile small males that are more susceptible to higher parasite loads may be unable to allocate as much energy to growth as large animals.

Tuesday January 30, 2018 2:40pm - 3:00pm CST
103B