Variation in prevalence and intensity of macroparasites in moose and their interactions with winter tick load in eastern Canada

Abstract

Wild animals are infected with a large diversity and abundance of parasites that can affect their behavior, growth, body condition, and ultimately their survival. Although the adverse effects of parasites and the mechanisms involved in the interactions between a host and its parasites are generally well studied, much less is known about the additive or synergistic effects of multiple parasite species on a host. Moose populations in eastern Canada are infected by several species of endoparasites. In the last decades, the intensity of infestations by winter ticks, an ectoparasite, on moose have increased as a result of increased moose densities and favorable weather conditions that benefit winter tick survival. We aimed to document the diversity, intensity, prevalence, and distribution of different parasite species of moose in southern Quebec, Canada. We then evaluated the potential interaction between winter tick and endoparasites of moose, and we evaluated the effect of the simultaneous presence of ticks and endoparasites on moose body condition. To do so, we collected organs to identify and count endoparasite species, estimate winter tick abundance, and measure subcutaneous fat thickness from 174 hunted moose in fall 2019 in 8 regions of Quebec. Our results showed that the prevalence and intensity of winter tick and gastrointestinal parasites differed among regions, as well as the prevalence of the heart parasite Taenia krabbei and the intensity of lung parasite Echinoccocus granulosus. Moose body condition, however, was not influenced by the simultaneous presence of winter tick and endoparasites. The documentation of the interactive effects of multiple parasite species on a host is fundamental given that future environmental conditions in temperate climate will favor the reproduction, development, and survival of several parasite species, which could affect parasite diversity and abundance in the environment and modify host–parasite dynamics.