Examining plant-parasitoid interactions in tritrophic systems

the demonstration that parasitoids are attracted to volatile compounds released by plants in response to herbivore feeding has generated a great deal of interest over the past ten years. the release of volatile signals by plants occurs not only in response to tissue damage but is also specifically initiated by exposure to herbivore salivary secretions. although some volatile compounds are stored in plant tissues and immediately released when damage occurs, others are induced by herbivore feeding and released not only from damaged tissue but also from undamaged leaves. thus, damage localized to only a few leaves results in a systemic response and the release of volatiles from the entire plant. new evidence suggests that, in addition to being highly detectable and reliable indicators of herbivore presence, herbivore-induced plant volatiles may convey herbivore-specific information that allows parasitoids to discriminate even closely-related herbivore species at long range. here we give an overview of the recent developments in the investigation of plant-parasitoid interactions.