McCoy, Karen M.Sc. - Advisor: Prof. T.D. Nudds

TRANSMISSION ECOLOGY OF PARELAPHOSTRONGYLUS TENUIS: FACTORS AFFECTING PREVALENCE IN GASTROPOD POPULATIONS

Current understanding of the transmission of Parelaphostrongylus tenuis through gastropod intermediate hosts can not explain high and low prevalence, respectively, in white-tailed deer (Odocoileus virginianus) and gastropod populations. I found interspecific variation in the climbing of gastropods, and in the representation of species in collections from trap samples, consistent with a hypothesis that prevalence is underestimated in gastropod populations due to sampling bias. Conversely, gastropods avoided infected deer feces, suggesting that prevalence may actually be low in these populations. Further, the hypothesis that P. tenuis altered gastropod climbing behaviour, thus increasing the probability of transmission to deer, was not supported and so could not account for high prevalence in deer. I eliminated some of the hypotheses advanced to explain observed prevalence and suggest that Deroceras laeve and Succinea ovalis should be focal species for further examination of the relative importance of gastropod species in transmission.