Plant responses induced by herbivores.

Physiological and chemical traits of many plant species change in response to real or simulated herbivory. These changes often have significant impacts on behavior, growth, survivorship, feeding and oviposition of insects. However, evidence that plants gain direct or indirect protection from insect enemies thereby is equivocal at present. Evidence is lacking for an impact of induced defenses on insect population dynamics, but few studies have sought it. More detailed studies of plant physiology, biochemistry, genetics and net benefit to individual plants are needed to identify the adaptive significance of induced defenses.