Browsing by Subject "gastropod"

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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.
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    SPATIAL AND TEMPORAL ABUNDANCE OF GASTROPOD INTERMEDIATE HOSTS IN NORTHEASTERN MINNESOTA WITH IMPLICATIONS FOR PARELAPHOSTRONGYLUS TENUIS RISK IN MOOSE
    (2015-04) Cyr, Tim
    Parelaphostrongylus tenuis is a nematode meningeal parasite that requires white-tailed deer primary hosts and terrestrial gastropod intermediate hosts to complete its life cycle. While white-tailed deer are the only host in which P. tenuis can complete its life cycle, P. tenuis can be lethal to moose and other cervids that accidentally ingest infected gastropods while browsing. Describing the spatial and temporal changes in gastropod abundance will increase understanding about the risk of P. tenuis infection by moose at the individual and population levels. We used cardboard traps and hand searches to estimate terrestrial gastropod species composition and abundance in representative vegetation communities in Northeastern Minnesota. We also tested the gastropods for P. tenuis infection. We also measured various environmental factors that may explain terrestrial gastropod distribution. Gastropods were most abundant in conifer and regenerating forests (11.2/m2) while mixed forests had the lowest gastropod abundance (7.0/m2). Gastropods were more abundant in September than June and July and none were collected in November. Seventy four gastropods were found climbing on vegetation up to three meters off the ground. 0.1% of the identified gastropods were infected with P. tenuis. Spatial and temporal changes in gastropod abundance could provide different risk levels of P. tenuis infection for moose. Our research will help to evaluate infection risk in the most common moose habitats in Northeastern Minnesota.