Chemotype of tansy (Tanacetum vulgare L.) determines aphid genotype and its associated predator system

Field assessments and genetic analyses on tansy aphid, Metopeurum fuscovirideStroyan were made aiming to investigate whether a specialist aphid species and its associated predator density differ between chemotypes of the plant host, tansy, and whether the essential oil composition of the plant host determines the genetic differences observed between colonies of M.fuscoviride inhabiting these different chemotypes. Tansy plants were defined after volatile extractions as Camphor Pure and Borneol Pure, respectively, with hybrid chemotypes defined as Camphor Hybrid, Borneol Hybrid, and Thujone Hybrid, respectively. Ladybird beetles, Coccinella septempunctata (L.), clearly dominated Pure Camphor plants, whereas significantly higher numbers of the nursery web spider, Pisaura mirabilis (Clerck), were detected on Borneol Pure and Borneol Hybrid plants. Genetic analyses using five polymorphic microsatellite markers revealed that higher genetic similarity existed between M.fuscoviride aphids from Borneol Pure and Borneol Hybrid plants and between Camphor Pure and Camphor Hybrid plants, respectively, whereas a lower level of genetic similarity was seen between these aphids from Thujone Hybrid plants. Accordingly, it is possible that host plant-adapted species can create much context-dependency in the nature and strength of predation effects, which may in turn alter costs and benefits of host plant chemical differentiations, or even the prey genotype variations.(c) 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114, 709-719.