A meta-analytical evaluation of ecological factors driving induced expression of plant volatiles

Herbivore-induced plant volatiles (HIPVs) have important ecological roles for herbivores, predators/parasitoids, insects, and plants.  Herbivores use them to identify susceptible/resistant hosts. Predators/parasitoids locate their prey/hosts using these cues.  Even plants can sense changes in the volatiles released by their neighbors, and prepare their defenses for herbivores (Hare, 2011).  Our objective was determine if there are universal themes in the composition and quantity of herbivore induced plant volatiles due to evolutionary history, herbivore feeding style, and ecological context which could give insight into these key signals.  We conducted a meta-analysis of studies that had measured both HIPVs and ambient volatile levels.  We scored the total amount of volatiles, each individual volatile compound produced and the broader classes of volatiles.  We also scored more general information about the plant and herbivore used such as family, functional group, and area or origin for plants and feeding guild, diet breadth, and area of origin for insects.  We found strong effects due to evolutionary history, herbivore feeding style and ecology.  Interestingly, co-evolution between insects and plants did not have a significant effect on total volatile production.