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Effects of host characteristics and parasite intensity on growth and fecundity of Trichostrongylus retortaeformis infections in rabbits

Published online by Cambridge University Press:  07 January 2009

C. CHYLINSKI
Affiliation:
Division of Animal Production and Public Health, Faculty of Veterinary Medicine, The University of Glasgow, GlasgowG61 1QH, UK
B. BOAG
Affiliation:
Division of Animal Production and Public Health, Faculty of Veterinary Medicine, The University of Glasgow, GlasgowG61 1QH, UK
M. J. STEAR
Affiliation:
Division of Animal Production and Public Health, Faculty of Veterinary Medicine, The University of Glasgow, GlasgowG61 1QH, UK
I. M. CATTADORI*
Affiliation:
Division of Animal Production and Public Health, Faculty of Veterinary Medicine, The University of Glasgow, GlasgowG61 1QH, UK Center for Infectious Disease Dynamics, Department of Biology 208 Mueller Laboratory, The Pennsylvania State University, University Park, PA16802, USA
*
*Corresponding author: Division of Animal Production and Public Health, Faculty of Veterinary Medicine, Glasgow University, GlasgowG61 1QH, UK. E-mail: imc3@psu.edu

Summary

Host-mediated responses and parasite density-dependent processes can have a major influence on the growth and fecundity of parasitic nematodes. However, host characteristics and parasite intensity consistently change during the course of an infection and these could affect worm length and number of eggs in a non-constant way. We used a free-living population of rabbits naturally infected with Trichostronglyus retortateformis and examined how adult nematode length and the number of eggs in utero were affected by host characteristics (i.e. age, sex, breeding status) and parasite intensity, in a seasonal environment, between 2004 and 2007. Nematode length and number of eggs in utero decreased exponentially with host age; in contrast, parasite intensity increased, peaked in juveniles and decreased in older hosts. These patterns were consistent between rabbit cohorts. A negative relationship was observed between parasite intensity and nematode length, as well as number of eggs. Nematode length was strongly affected by nematode sex and host age, while the number of eggs was mainly influenced by nematode length. The direct influence of host-mediated effects appeared quantitatively more important than parasite density dependence in controlling length and egg production in naturally infected wild rabbits. However, their relative contribution changed during the course of the infection such that, while host immunity still influenced worm numbers, the direct effect of density-dependent interactions contributed the most at high parasite intensities.

Type
Research Article
Copyright
Copyright © 2009 Cambridge University Press

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