Abstract
BackgroundUmingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis are two potentially pathogenic lungworms of caribou and muskoxen in the Canadian Arctic. These parasites are currently undergoing northward range expansion at differential rates. It is hypothesized that their invasion and spread to the Canadian Arctic Archipelago are in part driven by climate warming. However, very little is known regarding their physiological ecology, limiting our ability to parameterize ecological models to test these hypotheses and make meaningful predictions. In this study, the developmental parameters of V. eleguneniensis inside a gastropod intermediate host were determined and freezing survival of U. pallikuukensis and V. eleguneniensis were compared.MethodsSlug intermediate hosts, Deroceras laeve, were collected from their natural habitat and experimentally infected with first-stage larvae (L1) of V. eleguneniensis. Development of L1 to third-stage larvae (L3) in D. laeve was studied at constant temperature treatments from 8.5 to 24 °C. To determine freezing survival, freshly collected L1 of both parasite species were held in water at subzero temperatures from -10 to -80 °C, and the number of L1 surviving were counted at 2, 7, 30, 90 and 180 days.ResultsThe lower threshold temperature (T0) below which the larvae of V. eleguneniensis did not develop into L3 was 9.54 °C and the degree-days required for development (DD) was 171.25. Both U. pallikuukensis and V. eleguneniensis showed remarkable freeze tolerance: more than 80% of L1 survived across all temperatures and durations. Larval survival decreased with freezing duration but did not differ between the two species.ConclusionBoth U. pallikuukensis and V. eleguneniensis have high freezing survival that allows them to survive severe Arctic winters. The higher T0 and DD of V. eleguneniensis compared to U. pallikuukensis may contribute to the comparatively slower range expansion of the former. Our study advances knowledge of Arctic parasitology and provides ecological and physiological data that can be useful for parameterizing ecological models.
Highlights
Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis are two potentially pathogenic lungworms of caribou and muskoxen in the Canadian Arctic
We fitted a linear model for our parameter estimates for three reasons: (i) linear model fitted our data well, (ii) our objective was to derive days required for development (DD) and Lower development threshold (T0), and (iii) we wanted to compare to other protostrongylids, especially with lungworm U. pallikuukensis, and linear models were used to derive the parameters for these protostrongylids
From equation 1, the threshold temperature was determined as T0 = 9.54 °C and DD was 171.25, which are within the range determined for other northern protostrongylids (Table 2)
Summary
These parasites are currently undergoing northward range expansion at differential rates. The summers are short, cool, and dry, providing a narrow developmental window for ectotherms, including parasites, and a short growing season for endotherms and plants [1,2,3]. Nematodes are often used as sentinels of climate-change impacts because larval development inside the intermediate host is temperature-driven and free-living larval stages are influenced by the external environment [5, 11,12,13]. In order to determine the current and future impacts of climate change on disease dynamics and ecosystem health, laboratory- and field-based experiments can shed light on the temperature-dependent biology and ecology of both nematode parasites and host species [16,17,18]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
