HERBIVORE-INFESTED PLANTS SELECTIVELY ATTRACT PARASITOIDS

In response to insect herbivory, plants synthesize and emit blends of volatile compounds from their damaged and undamaged tissues, which act as important host-location cues for parasitic insects(1-3). Here we u se chemical and behavioural assays to show that these plant emissions can transmit herbivore-specific information that is detectable by para sitic wasps (parasitoids), Tobacco, cotton and maize plants each produ ce distinct volatile blends in response to damage by two closely relat ed herbivore species, Heliothis virescens and Helicoverpa tea. The spe cialist parasitic wasp Cardiochiles nigriceps exploits these differenc es to distinguish infestation by its host, H. virescens, from that by H. zea. The production by phylogenetically diverse plant species and t he exploitation by parasitoids of highly specific chemical signals, ke yed to individual herbivore species, indicates that the interaction be tween plants and the natural enemies of the herbivores that attack the m is more sophisticated than previously realized.