title: Consequences of coinfection with protective symbionts on the host phenotype and symbiont titres in the pea aphid system.
abstract: Symbiotic associations between microbes and insects are widespread, and it is frequent that several symbionts share the same host individual. Hence, interactions can occur between these symbionts, influencing their respective abundance within the host with consequences on its phenotype. Here, we investigate the effects of multiple infections in the pea aphid, Acyrthosiphon pisum, which is the host of an obligatory and several facultative symbionts. In particular, we study the influence of a coinfection with 2 protective symbionts: Hamiltonella defensa, which confers protection against parasitoids, and Rickettsiella viridis, which provides protection against fungal pathogens and predators. The effects of Hamiltonella-Rickettsiella coinfection on the respective abundance of the symbionts, host fitness and efficacy of enemy protection were studied. Asymmetrical interactions between the 2 protective symbionts have been found: when they coinfect the same aphid individuals, the Rickettsiella infection affected Hamiltonella abundance within hosts but not the Hamiltonella-mediated protective phenotype while the Hamiltonella infection negatively influences the Rickettsiella-mediated protective phenotype but not its abundance. Harboring the 2 protective symbionts also reduced the survival and fecundity of host individuals. Overall, this work highlights the effects of multiple infections on symbiont abundances and host traits that are likely to impact the maintenance of the symbiotic associations in natural habitats.
authors: IGEPP, Agrocampus Ouest, INRA, Université de Rennes 1, Université Bretagne-Loire, Rennes, France.
authors: Mélanie
authors: M
authors: Leclair
authors: IGEPP, Agrocampus Ouest, INRA, Université de Rennes 1, Université Bretagne-Loire, Rennes, France.
authors: Sarah
authors: S
authors: Polin
authors: IGEPP, Agrocampus Ouest, INRA, Université de Rennes 1, Le Rheu, France.
authors: Thibaut
authors: T
authors: Jousseaume
authors: IGEPP, Agrocampus Ouest, INRA, Université de Rennes 1, Le Rheu, France.
authors: Jean-Christophe
authors: JC
authors: Simon
authors: IGEPP, Agrocampus Ouest, INRA, Université de Rennes 1, Le Rheu, France.
authors: Akiko
authors: A
authors: Sugio
authors: IGEPP, Agrocampus Ouest, INRA, Université de Rennes 1, Le Rheu, France.
authors: Stéphanie
authors: S
authors: Morlière
authors: Bioproduction Research Institute, AIST, Tsukuba, Japan.
authors: Takema
authors: T
authors: Fukatsu
authors: Graduate School of Science and Engineering, University of Toyama, Toyama, Japan.
authors: Tsutomu
authors: T
authors: Tsuchida
authors: IGEPP, Agrocampus Ouest, INRA, Université de Rennes 1, Université Bretagne-Loire, Rennes, France.
authors: Yannick
authors: Y
authors: Outreman
mesh_terms: D000818:Animals; D001042:Aphids / Q000235:genetics / Q000382:microbiology* / Q000469:parasitology; D060085:Coinfection; D044125:Coxiellaceae / Q000502:physiology*; D004755:Enterobacteriaceae / Q000502:physiology*; D005260:Female; D006790:Host-Parasite Interactions; D008297:Male; D010641:Phenotype; D013559:Symbiosis; D014863:Wasps / Q000502:physiology*
keywords: Acyrthosiphon pisum; Hamiltonella defensa; host fitness; multiple infections; protective symbionts; symbiont abundance