Catherine Pouchet
Master student
Department of Biology
Laval University

Supervised by:

Steeve Côté (Regular member)

Christian Dussault (External collaborator)

Research project description

Combined effects of parasitism on moose body condition in relation with winter ticks (Dermacentor albipictus) load and environmental conditions

Introduction: Host-parasite relationships are a fragile balance that can be altered by several environmental factors. Host population density and climate change can modulate the prevalence and intensity of parasite infestation, which may have a direct impact on host body condition and population dynamics. In addition to winter ticks (Dermacentor albipictus), moose (Alces alces) in eastern North America are infected by a large variety of endoparasite species. The combined effects of these parasites can be antagonistic or additive. Moose endoparasites and ectoparasites could interact, possibly exacerbating the effects that a single parasite species would have on its host. Considering environmental conditions, we will assess the impact of different parasite species on moose body condition to understand potential synergetic effects within a common host. First, we will assess to what extent moose body condition is determined by winter tick and endoparasite loads. We will also determine whether there is a synergetic or antagonist relation between moose endoparasites and ectoparasites, i.e whether winter tick load modulates endoparasite loads in moose. Finally, we will determine whether parasite loads depend on moose population density and climatic conditions. Study sites: We will sample three major hunting areas in Quebec. Zones 1 and 2 (according to the Quebec government's nomenclature) correspond to the Lower St. Lawrence-Gaspésie Peninsula, where moose density was estimated at 8.9 moose/10 km2 in winter 2018 (MFFP, 2018). Zone 10 corresponds to Outaouais, where moose density was estimated at 1.5 moose/10 km2 in 2010 (MFFP, 2015). Finally, zone 27 corresponds to the National Capital. We will sample in the Seigneurie de Beaupré, where the moose density was estimated at 14.8 moose/10 km2 in 2013 (MNR, 2013). We will also use natural mortality among marked moose from 4 regions of Quebec within a controlled tick load experimental study, on which we will be able to perform a more detailed autopsy than for hunted animals. Material and methods: We will use weather conditions (date of complete snow cover melting in spring, average of daily minimum and maximum temperatures in summer and fall, average of daily relative humidity in summer and fall) from Environment Canada stations for each sampled area. To determine the intensity of parasitic infestation, we will use tick counts and collected organs. We will do a count and visual identification for endoparasites of the liver, heart, lungs and brain. We will take a blood sample and use PCR to identify blood microparasites and we will take part of the intestinal content for the identification and counting of gastrointestinal parasites. We will weigh moose and measure subcutaneous fat thickness to assess their body condition, corrected for sex and age. Expected results: We expect a better understanding of parasitic infections on moose health in Quebec in a context of climate change and an increase of winter tick prevalence. This project will allow us to determine whether there are potential interactions between winter ticks and endoparasites, i.e whether the presence of ticks on moose contributes to secondary endoparasitic infections, and whether the combined effect of these infestations are additive or not on moose body condition. This project will allow us to quantify tick infestation and provide us with an overall picture of endoparasites diversity and abundance in moose in Quebec. Finally, we expect a better understanding of how climatic conditions and increased moose densities in certain regions of Quebec influence parasitic infections.

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