Summary: © 2005 The Netherlands Entomological Society Entomologia Experimentalis et Applicata 115: 97105, 2005 97
Blackwell Publishing, Ltd.
Future directions in the study of induced plant
responses to herbivory
Anurag A. Agrawal*
Department of Ecology and Evolutionary Biology, Cornell University, Corson Hall, Ithaca, NY 14853-2701, USA
Accepted: 11 February 2005
Key words: plantinsect interactions, phenotypic plasticity, induced defense, herbivory, phylogeny,
insect community structure, costs of defense, plant resistance
Abstract This paper reviews current progress and makes recommendations for future studies of induced plant
responses to herbivory in three research areas: the role of induction in structuring herbivore
communities, costs associated with the expression of induced responses, and theory and data on the
macro-evolution of induced responses. It is argued that although mechanistic approaches will be
important for progress, it is also critical to maintain a holistic approach, including a consideration of
field environments, multi-species interactions, and patterns over ecological and evolutionary time.
Induced plant responses to herbivory that reduce the pre-
ference or performance of subsequently feeding herbivores
are a paradigm of plant defense (Karban & Baldwin,1997).
Originally formulated as a potential novel mechanism of