Volatile Chemical Interaction Between Undamaged Plants: Effects at Higher Trophic Levels

This chapter discusses whether plant chemical communication is a mechanism by which plant genetic diversity can affect the natural enemies of herbivores. Plant genetic diversity influences natural enemies, and these insects use volatile chemical cues to locate suitable habitats. However, the importance of chemical communication for these interactions has not been considered. In this chapter, the latest research on chemical communication between undamaged plants is reviewed. Evidence for the fact that volatile chemical communication between weeds and barley, and between different barley genotypes, can influence host plant and habitat selection by aphid natural enemies, polyphagous ladybirds and parasitic wasps, is presented. The results suggest that aphid natural enemies may recognise the effects of plant–plant volatile interaction and volatile mixing as cues denoting favourable habitats. This represents a new aspect of the ecology of plant communication that may be exploited for sustainable plant protection.