|Tumlinson Iii, James
Submitted to: Phytochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/1997
Publication Date: N/A
Interpretive Summary: When cotton plants are damaged by beet armyworm caterpillars feeding on the leaves they emit an odor, comprised of a blend of volatile chemicals, that attracts natural enemies of the caterpillars. Scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL, have discovered that several of the constituents of this odor are freshly synthesized by the plants in direct response to the caterpillar feeding. Furthermore, this synthesis occurs not only in the damaged leaves, but also in undamaged leaves distant from the site of damage. Thus, when the plant is attacked by caterpillar pests the entire plant synthesizes and releases odors that attract natural enemies of the pests. Plants that are not wounded do not release these odors. When this important defense mechanism of plants is more fully understood it can be enhanced in crop plants. Then, plants under attack by insects will be more attractive to natural enemies of the herbivores. This, in combination with other methods, can be used to develop more effective biological control of crop pests.
Technical Abstract: Cotton plants (Gossypium hirsutum) damaged by herbivorous insects release volatile compounds that act as chemical signals to attract natural enemies of the herbivore to the damaged plant. Feeding by beet armyworm larvae (Spodoptera exigua) on the lower leaves of cotton plants triggers the systemic release of six readily detectable terpenes and hexenyl acetate, a product of the lipoxygenase pathway. Labeling with [13C] carbon dioxide established that the terpenes released systemically after herbivore damage are synthesized de novo at or near the site of emission. Hexenyl acetate rapidly incorporated 13C into the acetate but not the hexenyl moiety within our pulse labeling interval. Activation of the lipoxygenase pathway in undamaged leaves of insect damaged plants, as it relates to the release of volatiles' is discussed. Copyright 1997 Elsevier Science Ltd.