Plant and insect microbial symbionts alter the outcome of plant-herbivore-parasitoid interactions: implications for invaded, agricultural and natural systems

1. Understanding how soil microbial communities influence plant interactions with other organisms, and how this varies with characteristics of the interacting organisms, is important for multiple systems. Solanum spp. are a suitable model for trophic interactions in studies of agricultural and natural systems and can also provide useful corollaries in invaded systems. This study examined the influence of soil mutualist arbuscular mycorrhizal (AM) fungi on growth of different Solanum types fed on by the potato aphid, Macrosiphum euphorbiae, in relation to presence of the aphid facultative endosymbiont Hamiltonella defensa. 2. Four Solanum types comprising two wild species, S. berthaultii and S. polyadenum, and two accessions of S. tuberosum, were grown with or without AM fungi and infested with one of four clonal lines of a single M. euphorbiae genotype (two with and two without H. defensa). Two experiments were conducted to i) characterise plant responses to AM fungi and aphids and ii)...