Keystone Herbivores and the Evolution of Plant Defenses

Plants need to defend themselves against a diverse and dynamic herbivore community. Such communities may be shaped by keystone herbivores that through their feeding alter the plant phenotype as well as the likelihood of attack by other herbivores. Here, we discuss such herbivores that have a large effect on the interaction network structure with associated fitness consequences for the plant, as dominant agents of selection on plant defense traits. Merging the keystone herbivore concept with plant fitness and trait selection frameworks will provide an approach to identify which herbivores drive selection in complex multispecies interactions in natural and agricultural systems.