title: How herbivores coopt plant defenses: natural selection, specialization, and sequestration.
abstract: We review progress in understanding sequestration by herbivorous insects, the use of plant chemical defenses for their own defense. We incorporate sequestration into the framework of plant-insect coevolution by integrating three hierarchical issues: (1) the relationship between dietary specialization and sequestration of plant defenses, (2) the physiological mechanisms involved in sequestration, and (3) how sequestration evolves via interactions between trophic levels. Sequestration is often associated with specialization, but even specialized sequestration is not an evolutionary dead-end. Despite considerable progress in understanding physiological mechanisms, detailed knowledge of how plant toxins cross the insect gut epithelium is still largely lacking. Sequestration is likely a major vehicle for coevolutionary escalation in speciose plant-insect-predator interactions, suggesting that a strictly bitrophic view is untenable.
authors.affiliation: Institut für Insektenbiotechnologie, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany. Electronic address: Georg.Petschenka@googlemail.com.
authors.forename: Georg
authors.initials: G
authors.lastname: Petschenka
authors.affiliation: Ecology and Evolutionary Biology, Cornell University, E425 Corson Hall, Ithaca, NY 14853 USA.
authors.forename: Anurag A
authors.initials: AA
authors.lastname: Agrawal
mesh_terms: D000818:Animals; D005075:Biological Evolution; D060434:Herbivory; D006790:Host-Parasite Interactions / Q000502:physiology*; D007313:Insecta / Q000502:physiology*; D018521:Plant Physiological Phenomena; D010944:Plants / Q000469:parasitology*; D012641:Selection, Genetic