CONICET | Buscador de Institutos y Recursos Humanos

The guanaco (Lama guanicoe) is the dominant herbivore of South American arid lands. In Reserva Provincial La Payunia (Argentina) there is a population of 10,000 individuals, part of which is live-sheared as part of a sustainable use program. Recently, the importance of parasites for wildlife population dynamics has been increasingly recognized. Moreover, stress can affect a populations ability to thrive, as it jeopardizes the immunity of individuals, increasing their vulnerability to parasites. With the aim of investigating factors associated with variability in gastrointestinal parasitism in guanacos, faeces collected during eight sampling sessions in Payunia were analized with cualitative and cuantitative copro-parsitological techniques. Additionally, plasmatic cortisol was determined by radioimmunoassay. Parasites found belonged to the Genera Eimeria, Nematodirus, Trichuris, and Capillaria, but the two former largely prevailed. Prevalence of Nematodirus spp. and oocyst counts of Eimeria spp. were significantly higher in spring, and had their lowest values in summer. Bachelor groups had lower Eimeria spp. intensities than family and mixed groups, while the latter had higher prevalence of Nematodirus spp. than other social groups. In males, oocyst counts and plasmatic cortisol were negatively correlated. Faeces from dung piles have lower loads of Eimeria spp. oocysts than those shed away from piles, even within the same host age group. Guanacos with higher intensities of Nematodirus spp. and Eimeria spp. had significantly lower body condition. These results are important to better understand how parasite ecology may influence guanaco population dynamics, which may be key knowledge for effective management and conservation programs.

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