title: Protection first then facilitation: a manipulative parasite modulates the vulnerability to predation of its intermediate host according to its own developmental stage.
abstract: Many trophically transmitted parasites with complex life cycles manipulate their intermediate host behavior in ways facilitating their transmission to final host by predation. This facilitation generally results from lowering host's antipredatory defenses when the parasite is infective to the final host. However, a recent theoretical model predicts that an optimal parasitic strategy would be to protect the intermediate host from predation when noninfective, before switching to facilitation when the infective stage is reached. We tested this hypothesis in the fish acanthocephalan parasite Pomphorhynchus laevis using the amphipod Gammarus pulex as intermediate host. Gammarids parasitized by noninfective stage of P. laevis (acanthella) hid significantly more under refuges than uninfected ones. In addition, acanthella-infected gammarids were less predated upon by trout than uninfected ones. As predicted, a switch toward decreased antipredatory behavior of G. pulex and enhanced vulnerability to predation was found when P. laevis reached the stage infective to its final host. The parasites appear to be able to exploit plasticity in host antipredatory responses, and shift the host optimal response toward their own optimal balance.
authors: Université de Bourgogne, Laboratoire Biogéosciences, UMR CNRS 5561, Equipe Ecologie Evolutive, 6 Boulevard Gabriel, 21000 Dijon, France. lucile.dianne@u-bourgogne.fr
authors: Lucile
authors: L
authors: Dianne
authors: Marie-Jeanne
authors: MJ
authors: Perrot-Minnot
authors: Alexandre
authors: A
authors: Bauer
authors: Mickaël
authors: M
authors: Gaillard
authors: Elsa
authors: E
authors: Léger
authors: Thierry
authors: T
authors: Rigaud
mesh_terms: D000049:Acanthocephala / Q000254:growth & development*; D033304:Amphipoda / Q000469:parasitology*; D000818:Animals; D004924:Escape Reaction; D020387:Food Chain; D005602:France; D006790:Host-Parasite Interactions; D011235:Predatory Behavior; D014337:Trout / Q000469:parasitology / Q000502:physiology