Browsing by Subject "Parelaphostrongylus tenuis"

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    Moose and deer resource selection and co-occurrence in northeast Minnesota
    (2019-08) McGraw, Amanda
    A parasite, Parelaphostrongylus tenuis, carried by white-tailed deer (Odocoileus virginianus) has often been cited as a significant factor contributing to moose (Alces alces) population declines. Moose suffer from neurologic disease and usually die when infected with P. tenuis. The strength of the three-way relationship between moose, deer, and P. tenuis, and the resulting negative impact on moose health, is thought to be driven by deer densities. Despite its importance for moose and deer management, only one peer-reviewed study to date has tested the relationship between deer and moose densities, and therefore the potential for parasite-mediated competition between moose and deer, using empirical data. A deer density threshold above which moose populations declined was identified using the empirical data collected for the study. However, the nature of the data and apparent outliers suggest that the modeling approach used to develop that threshold may not have been appropriate. Here we tested, using data from the original study, whether alternative models, including linear models and negative binomial models would be less sensitive to outliers and could better explain the relationship between deer and moose densities in this study system. We found no evidence in our analysis that moose density decreases as deer density increases. We conclude that while the proposed moose-deer-P. tenuis relationship could be partially density dependent, additional factors such as frequency dependence of disease transmission and shared use of resources by moose and deer should also be considered.
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    R code and data for "Spatial compartmentalization: a nonlethal predator mechanism to reduce parasite transmission between prey species"
    (2021-11-15) Oliveira-Santos, L. Gustavo R.; Moore, Seth A.; Severud, William J.; Forester, James D.; Isaac, Edmund J.; Chenaux-Ibrahim, Yvette M.; Garwood, Tyler; Escobar, Luis E.; Wolf, Tiffany M.; seve0135@umn.edu; Severud, William J.
    This collection of files provides data and R code supporting the publication "Spatial compartmentalization: a nonlethal predator mechanism to reduce parasite transmission between prey species" in review at Science Advances. We provide all necessary code to reproduce the analysis along with simulated movement data of white-tailed deer, moose, and wolves.
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    R code and data for "Terrestrial gastropod species-specific responses to forest management: implications for Parelaphostrongylus tenuis transmission to moose"
    (2022-12-14) Severud, William J; Petz Gigure, Matt; Walters, Tyler; Garwood, Tyler J.; Teager, Kim; Marchetto, Katherine M.; Oliveira-Santos, L. Gustavo R.; Moore, Seth A.; Wolf, Tiffany M.; seve0135@umn.edu; Severud, William
    Landscape management can influence the distribution, abundance, and diversity of the terrestrial gastropods that host known parasites of managed species of ungulates. Multiple taxa of terrestrial gastropods are important intermediate hosts in the lifecycle of the parasitic nematode Parelaphostrongylus tenuis, for which white-tailed deer (Odocoileus virginianus) are definitive hosts. Moose (Alces alces) become infected with P. tenuis when they incidentally ingest gastropod intermediate hosts, leading to morbidity and mortality. Populations of moose in Minnesota have declined and P. tenuis infection has been identified as a leading cause of mortality. We investigated the role of forest management disturbance on the terrestrial gastropod community, and specifically known intermediate host species of P. tenuis, on the Grand Portage Indian Reservation in northeastern Minnesota, USA, where moose are an important subsistence species to the Grand Portage Band of Lake Superior Chippewa. Field crews surveyed gastropods through timed searches of soil and litter, and opportunistic collections from browse and pellets of white-tailed deer and moose. We digested all identified gastropods to determine prevalence of P. tenuis infection. We examined gastropod community responses to management and forest cover type using multivariate regressions. We additionally used regressions to examine total gastropod richness and abundance, as well as P. tenuis intermediate host responses to cover type, soil moisture class, canopy cover, treatment, and years since treatment. Digestions detected no infected gastropods from the 621 identified specimens. Gastropod community assemblages differed with recent understory treatment, but no other predictors. Total gastropod abundance, richness, and host abundance (liberal definition, including Deroceras spp.) were lower in sites treated within the last five years. For known intermediate host taxa, we observed species-specific responses to forestry treatments through time. Specifically, Deroceras spp. recolonized sites post-treatment (0–30 years), Discus cronkhitei were higher in abundance immediately following treatment, and the Succinea ovalis group, along with pooled intermediate hosts, displayed no discernable patterns. Our results underscore the complexity of P. tenuis lifecycles and transmission dynamics to moose, the importance of management disturbance and disturbance frequency in regulating gastropod populations, and the potential of forest management treatments to reduce P. tenuis infection in moose.