Plant communication and herbivore population dynamics

Insect herbivory can significantly affect plant metabolism. Some of these induced changes, notably those of non-volatile and volatile secondary metabolites can function as chemical information that mediates diverse and complex interactions with herbivores. Here we test the hypothesis that plant induced responses to herbivory, as well as plant-to-plant chemical information transfer, affect insect herbivore movement and the distribution of herbivore damage within plant populations. We use the tall goldenrod, Solidago altissima, and its diverse arthropod community as a model as well as field and laboratory bioassays and chemical analytical tools to test this hypothesis.

We demonstrate that induced responses to herbivory significantly affect the movements of herbivores and so the distribution of herbivore damage within plant populations. As a consequence, insect herbivores function as major agents of natural selection on the inducibility of chemical resistance as well as the plants’ ability to transmit and receive chemical information in response to herbivore attacks. We discuss the implication of these findings for insect population dynamics and the probability for insect populations to outbreak.