Sophie Labaude PhD thesis

frEffect of the environment on the interaction between gammarids (Crustacea: Amphipoda) and their manipulative acanthocephalan parasites

Funding: école doctorale ES

Supervisors: Thierry Rigaud and Frank Cézilly

Beginning: october 2013

 

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Abstract

Many parasites with complex life cycle have developed the ability to alter the phenotype of their hosts. It is recognized that such changes in appearance and behavior are responsible for an increase in the probability of predation of their intermediate hosts by their definitive hosts. This phenomenon of parasite manipulation can have numerous consequences at the scale of the ecosystem, modifying the interactions between host populations and altering their ecological role. However, manipulative parasites received little attention from an ecological point of view. Thus, the effect of the environment on the interaction between these parasites and their hosts, in particular in terms of manipulation, is largely unknown. In this thesis, I studied the effect of the environment on the interaction between gammarids – ecologically important crustacean amphipods in rivers – and their acanthocephalan parasites. My experiments showed that the conditions of food resources and temperature experienced by gammarids during the development of their parasites influenced several infection parameters, but did not affect behavioral manipulation in terms of use of refuges. Nevertheless, while the geotaxis was not either effected by temperature, the impact of parasites on gammarids phototaxis was stronger at high temperature. Moreover, my studies showed that the cumulative effect of temperature and parasitism could alter the shredder role of gammarids. In a context of global changes, this work provides a better understanding of the importance of the impact of parasites on their hosts, allowing to make previsions on their subsequent ecological consequences.

 

Keywords

manipulative parasites, acanthocephalan, gammarids, environment, manipulation, ecological role, host, parasite

 

 

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Publications

Labaude, S., Cézilly, F., Tercier, X. & Rigaud, T. 2015. Influence of host nutritional condition on post-infection traits in the association between the manipulative acanthocephalan Pomphorhynchus laevis and the amphipod Gammarus pulex. Parasites & Vectors, 8, 403.

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Labaude, S., Rigaud, T. & Cézilly, F. 2015. Host manipulation in the face of environmental changes: ecological consequences. International Journal for Parasitology: Parasites and Wildlife, 4, 442-451.

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Labaude, S., Rigaud, T. & Cézilly, F. 2016. Additive effects of temperature and infection with an acanthocephalan parasite on the shredding activity of Gammarus fossarum (Crustacea: Amphipoda): the importance of aggregative behavior. Global Change Biology, doi: 10.1111/gcb.13490.

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