Consequences of coinfection with protective symbionts on the host phenotype and symbiont titres in the pea aphid system  

作　　者：Melanie Leclair Sarah Polin Thibaut Jousseaume Jean-Christophe Simon Akiko Sugio Stephanie Morliere Takema Fukatsu Tsutomu Tsuchida Yannick Outreman 

机构地区：[1]IGEPP, Agrocampus Ouest, INRA, Universite de Rennes 1, Universite Bretagne-Loire, Rennes, France [2]IGEPP, Agrocampus Ouest,INRA, Universit6 de Rennes 1, Le Rheu, France [3]Bioproduction Research Institute, AIST, Tsukuba, Japan [4]Graduate School of Science and Engineering, University of Toyama, Toyama, Japan

出　　处：《Insect Science》2017年第5期798-808,共11页昆虫科学（英文版）

摘　　要：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 pisurn, which is the host of an obligatory and several facultative symbionts. In particular, we study the influence of a coinfection with 2 protective symbionts： Harniltonella 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.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 pisurn, which is the host of an obligatory and several facultative symbionts. In particular, we study the influence of a coinfection with 2 protective symbionts： Harniltonella 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.

关 键 词：Acyrthosiphon pisum Hamiltonella defensa host fitness multiple infections protective symbionts symbiont abundance 

分 类 号：S858.31[农业科学—临床兽医学] TE988.2[农业科学—兽医学]