Plants as green phone

Abstract

Plants can act as vertical communication channels or ‘green phones’ linking soil-dwelling insects and insects in the aboveg- round ecosystem. When root-feeding insects attack a plant, the direct defense system of the shoot is activated, leading to an accu- mulation of phytotoxins in the leaves. The protection of the plant shoot elicited by root damage can impair the survival, growth and development of aboveground insect herbivores, thereby creating plant-based functional links between soil-dwelling insects and insects that develop in the aboveground ecosystem. The interac- tions between spatially separated insects below- and aboveground are not restricted to root and foliar plant-feeding insects, but can be extended to higher trophic levels such as insect parasitoids. Here we discuss some implications of plants acting as communication chan- nels or ‘green phones’ between root and foliar-feeding insects and their parasitoids, focusing on recent findings that plants attacked by root-feeding insects are significantly less attractive for the para- sitoids of foliar-feeding insects.