Parelaphostrongylus tenuis is a nematode that affects the brain of various cervids, bovids, and camelids. Gastropods are the intermediate host and vector for P. tenuis transmission and white-tailed deer (Odocoileus virginianus) are the definitive host. In areas with high white-tailed deer density, moose (Alces alces) may be at increased risk of exposure to P. tenuis. Moose are aberrant hosts to P. tenuis and can acquire the parasite by accidentally ingesting infected gastropods. Because moose browse at greater heights than most ungulates, gastropod climbing behavior may affect the likelihood of disease transmission. We hypothesized that gastropods climb in response to precipitation to avoid drowning. We researched gastropod climbing behavior and P. tenuis prevalence in climbing and non-climbing gastropods. We surveyed 24 plots (4 m x 3 m). Each plot was surveyed 3 times with 3-4 days between surveys. Gastropods were collected on the ground and trees of each plot. The family, tree species, and vertical location (if >0 cm), was recorded for each gastropod. We regressed vertical height against several variables including temperature and precipitation. Gastropods were sent to the Cornell Animal Health and Diagnostic Center to determine if they were infected with P. tenuis.
Results/Conclusions
Of the 253 gastropods collected, 37% were climbing. Of the 161 Arionidae collected, 30% were found climbing at an average height of 51.90 cm. Though all Limacidae were found climbing, they were at relatively low heights (average = 31.44 cm). Seventy-one percent of Zonitidae and 60% of Succinidae were found climbing, collected at average heights of 47.29cm and 94.28 cm, respectively. Of the Philomycidae collected, 48% were found climbing at an average height of 26.08 cm. More gastropods were collected on deciduous trees than coniferous trees (47 and 31, respectively), indicating a greater potential for disease transmission due to the overlap in gastropod location and moose browsing preferences. There was no relationship between precipitation and height at which gastropods were found (p = 0.5326). The effect of temperature on climbing height was significant and negative (p = 0.3767). Gastropods were found on bark, not leaves, which may indicate less opportunity for disease transmission since moose prefer to browse on leaves. Future work will evaluate the prevalence of P. tenuis to investigate whether gastropods, specifically those that climb, are a source of disease transmission to moose.