How do plants perceive folivorous insects to trigger specific defense and tolerance responses?

The ability of plants to recognize herbivores constitutes a form of plant immunity that is essential for plant survival. This process relies on the ability to perceive signals from the insect, to transmit this information to unattacked tissues to anticipate future attacks and to mount defenses that reduce insect performance and/or activate mechanisms that allow plants to tolerate the damage. Little is known about recognition events that trigger plant responses. One of these recognition systems involves the perception of insect-derived molecules delivered to plant cells during larval feeding.