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Article Dans Une Revue Parasitology Année : 2011

Parasite-induced changes in the diet of a freshwater amphipod : field and laboratory evidence

Résumé

Trophically transmitted parasites are likely to strongly in␣uence food web-structure. The extent to which they change the trophic ecology of their host remains nevertheless poorly investigated and ␣eld evidence is lacking. This is particularly true for acanthocephalan parasites whose invertebrate hosts can prey on other invertebrates and contribute to leaf-litter breakdown. We used a multiple approach combining feeding experiments, neutral lipids and stable isotopes to investigate the trophic ecology of the freshwater amphipod Gammarus roeseli parasitized by the bird acanthocephalan Polymorphus minutus. Infected compared to uninfected amphipods consumed as many dead isopods, but fewer live isopods and less leaf material. Infection had no in␣uence on the total concentration of neutral lipids. Contrary to what we expected based on laboratory ␣ndings, the nitrogen isotope signature, which allows for the estimation of consumer's trophic position, was not in␣uenced by infection status. Conversely, the carbon isotope signature, which is used to identify food sources, changed with infection and suggested that the diet of infected G. roeseli includes less perilithon (i.e. ␣xed algae on rocks, stones) but more terrestrial inputs (e.g. leaf material) than that of uninfected conspeci␣cs. This study shows evidence of changes in the trophic ecology of P. minutus-infected G. roeseli and we stress the need to complement feeding experiments with ␣eld data when investigating top-down e␣ects of infection in an opportunistic feeder which adapts its diet to the available food sources.
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Dates et versions

halsde-00580578 , version 1 (28-03-2011)

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Vincent Médoc, Christophe Piscart, Chafik Maazouzi, Laurent Simon, Jean-Nicolas Beisel. Parasite-induced changes in the diet of a freshwater amphipod : field and laboratory evidence. Parasitology, 2011, 138, pp.537-546. ⟨10.1017/S0031182010001617⟩. ⟨halsde-00580578⟩
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