Behaviorally plastic host-plant use by larval Lepidoptera in tri-trophic food webs

•Caterpillars show plastic behavioral responses to plants and carnivores.•These behavioral responses include diverse feeding and movement tactics.•Behavioral plasticity of herbivores plays an active role in plant–insect interactions.•Adaptive plasticity in herbivore behavior may stabilize populations and communities.

Plant–insect interactions research emphasizes adaptive plasticity of plants and carnivores, such as parasitoids, implying a relatively passive role of herbivores. Current work is addressing this deficit, with exciting studies of behavioral plasticity of larval Lepidoptera (caterpillars). Here I use select examples to illustrate the diversity of behaviorally plastic host-plant use by caterpillars, including anti-predator tactics, self-medication, and evasion of dynamic plant defenses, as proof of the agency of caterpillar behavior in plant–insect interactions. I emphasize the significance of adaptive behavioral plasticity of caterpillars in the context of tri-trophic interactions. Recent research on trait-mediated indirect interactions places adaptive behavioral plasticity of herbivores at the center of community and food web dynamics, with far-reaching consequences of issues such as community stability.