Plant-Mediated Interactions between Two Cereal Aphid Species: Promotion of Aphid Performance and Attraction of More Parasitoids by Infestation of Wheat with Phytotoxic Aphid Schizaphis graminum

Here, we investigated changes in physiological characteristics in wheat affected by phytotoxic-aphid Schizaphis graminum feeding and nonphytotoxic-aphid Sitobion avenae feeding. We also determined whether shared host-mediated interspecific interactions occur between S. graminum and S. avenae. S. graminum feeding but not S. avenae feeding induced significant chlorophyll loss and hydrogen peroxide accumulation in wheat. Gene-expression analysis and GC/MS metabonomic results indicated that S. graminum infestation induced stronger salicylic acid mediated defense responses than S. avenae did and significantly increased the contents of several amino acids in wheat leaves. Feeding on wheat preinfested with S. graminum significantly increased the reproduction of both aphids and shortened the development time of S. graminum. However, olfactometer bioassays showed that the parasitoid wasp Aphidius gifuensis was more attracted to the odors of S. graminum infested wheat than to those of control and S. avenae infested wheat. This study demonstrates that S. graminum and S. avenae feeding induced different defense responses and changes in plant nutritional quality. Additionally, plant-mediated interactions occurred between these cereal aphids.