|Tumlinson Iii, James|
Submitted to: Nature Magazine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 10, 1996
Publication Date: N/A
Interpretive Summary: We need to find ways to increase the use and effectiveness of natural organisms for biological control of insect pests of agricultural crops in order to reduce the use of pesticides and protect the environment. Scientists at the USDA, ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL have discovered that cotton plants damaged by feeding beet armyworm caterpillars synthesize and release odors that attract wasps that sting and kill the caterpillars. Thus, the plants can be very active in recruiting allies to help in their defense against their enemies. Also, wild varieties of cotton release more odor and are more attractive to the wasps than domestic varieties. Therefore, based on these findings it should be possible to develop crop varieties that are more attractive in recruiting parasites and predators of damaging insects. By enhancing the effectiveness of natural enemies, less pesticide will be required for pest control, thus reducing the cost of crop production and contamination of the environment.
Technical Abstract: Wounding of plant tissue by insect feeding triggers the release of volatile compounds, which have been implicated in attraction of natural enemies of the insect herbivores, and are derived from several biosynthetic pathways. The release of indole and several, but not all, terpenes is delayed and is induced only by interaction of a substance(s) in the oral secretions of the insects with damaged plant tissues. We used carbon 13 labeled carbon dioxide to show that cotton plants damaged by feeding beet armyworms synthesize induced volatile compounds de novo. Furthermore, carbon 13 labeled carbon dioxide volatiles were released from the leaves soon after synthesis and rapidly replaced by unlabeled compounds when carbon 13 labeled carbon dioxide was replaced by carbon 12 labeled carbon dioxide. This is the first demonstration of de novo synthesis of volatiles induced by insect damage to a plant and clearly shows the dynamic role of the plant in interactions with the second trophic level (insect herbivores) and third trophic level (parasitoids and predators).