Alpine Ibex show a great sexual dimorphism and a peculiar life history characterised by slow growth coupled with a marked age-related change in survival: high survival during early age stages followed by a sharp decline. This pattern is interpreted to be an adaptation to the limited energy resource that alpine environment may provide. Review in different host-parasite systems highlighted the strong influence of host sex and age on the parasite infection. We investigated whether in Alpine Ibex sexual differences in morphology and age-related changes in survival are reflected on the dynamics of parasite infection. Faecal samples were obtained from individually marked Ibex during the summer 2008 in Gran Paradiso National Park and analysed through modified McMaster method in order to determine number of parasite eggs per gram (EPG). The eggs have been classified as Nematodirus spp., Marshallagia marshalli and others Trichostrongylidae species. EPG have been considered for these three groups and for the total eggs count. The three parasite groups show a clear seasonal variation, with higher Trichostrongylidae species values on August, corresponding lowest levels of Nematodirus spp. and M. marshalli. The effect of sex on EPG has been observed only in M. marshalli. EPG increase with age in total eggs count and Trichostrongylidae species group. Moreover in Nematodirus spp., Ibex of different age showed a different dynamics of EPG emission during the summer months.
Factors affecting summer dynamics parasite egg emission in Alpine Ibex / R. Pedrotti, S. Orizio, N. Ferrari, A. Von Hardenberg, P. Lanfranchi. ((Intervento presentato al 21. convegno Meeting of the Alpine Ibex European Specialist Group (GSE-AIESG) tenutosi a Ceresole Reale nel 2008.
Factors affecting summer dynamics parasite egg emission in Alpine Ibex
N. Ferrari;P. LanfranchiUltimo
2008
Abstract
Alpine Ibex show a great sexual dimorphism and a peculiar life history characterised by slow growth coupled with a marked age-related change in survival: high survival during early age stages followed by a sharp decline. This pattern is interpreted to be an adaptation to the limited energy resource that alpine environment may provide. Review in different host-parasite systems highlighted the strong influence of host sex and age on the parasite infection. We investigated whether in Alpine Ibex sexual differences in morphology and age-related changes in survival are reflected on the dynamics of parasite infection. Faecal samples were obtained from individually marked Ibex during the summer 2008 in Gran Paradiso National Park and analysed through modified McMaster method in order to determine number of parasite eggs per gram (EPG). The eggs have been classified as Nematodirus spp., Marshallagia marshalli and others Trichostrongylidae species. EPG have been considered for these three groups and for the total eggs count. The three parasite groups show a clear seasonal variation, with higher Trichostrongylidae species values on August, corresponding lowest levels of Nematodirus spp. and M. marshalli. The effect of sex on EPG has been observed only in M. marshalli. EPG increase with age in total eggs count and Trichostrongylidae species group. Moreover in Nematodirus spp., Ibex of different age showed a different dynamics of EPG emission during the summer months.Pubblicazioni consigliate
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