The Temperature-Dependent Development of Varestrongylus eleguneniensis in Experimentally Infected Gastropod Hosts: A Threat with Climate Change?

Abstract

Varestrongylus eleguneniensis is a protostrongylid parasite infecting various subspecies of muskox, caribou, and moose in the Canadian Arctic. With climate change, its range has expanded in the past decade to novel areas, including Victoria Island. This paper investigates the temperature-dependence of the development of this parasite in hopes of understanding how climate change may affect this parasite and parasite-host dynamics in the future. Gastropod hosts (Deroceras laeve) collected from Alberta, Canada were experimentally infected and incubated at both 15oC and 24oC. They were digested at various intervals to determine the developmental time from the L1 to intermediate L3 stage. In Deroceras laeve, there was a direct relationship between larval developmental rate and temperature, and the regression equation y=0.0056x -0.0051 was determined to fit this model. From this equation, it was calculated that larvae of V. eleguneniensis are not expected to develop below the threshold temperature of 9.1oC, and the degree-days of development were determined to be 178.5. Knowledge of these developmental factors allows the direct comparison of V. eleguneniensis with other protostrongylids, and also provides the foundation for predicting future temporal and spatial patterns of this parasite’s distribution and transmission.