title: Virulence reaction norms across a food gradient.
abstract: Host-parasite interactions involve competition for nutritional resources between hosts and the parasites growing within them. Consuming part of a host's resources is one cause of a parasite's virulence, i.e. part of the fitness cost imposed on the host by the parasite. The influence of a host's nutritional conditions on the virulence of a parasite was experimentally tested using the mosquito Aedes aegypti and the microsporidian parasite Vavraia culicis. A condition-dependent expression of virulence was found and a positive relation between virulence and transmissibility was established. Spore production was positively influenced by host food availability, indicating that the parasite's within-host growth is limited by host condition. We also investigated how the fitness of each partner varied across the nutritional gradient and demonstrated that the sign of the correlation between host fitness and parasite fitness depended on the amount of nutritional resources available to the host.
authors.affiliation: Centre d'Etudes sur le Polymorphisme des Microorganismes, UMR CNRS-IRD 9926, 911 avenue d'Agropolis BP 64501, 34394 Montpellier 5, France. bedhomme@mpl.ird.fr
authors.forename: Stephanie
authors.initials: S
authors.lastname: Bedhomme
authors.forename: Philip
authors.initials: P
authors.lastname: Agnew
authors.forename: Christine
authors.initials: C
authors.lastname: Sidobre
authors.forename: Yannis
authors.initials: Y
authors.lastname: Michalakis
mesh_terms: D000330:Aedes / Q000469:parasitology* / Q000502:physiology; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001824:Body Constitution; D001938:Brazil; D003163:Competitive Behavior / Q000502:physiology*; D006790:Host-Parasite Interactions; D016814:Microsporidia / Q000254:growth & development* / Q000472:pathogenicity*; D008954:Models, Biological; D014774:Virulence / Q000502:physiology