Author
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De Moraes, Consuelo |
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MESCHER, M. - UNIV. GEORGIA |
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Tumlinson Iii, James |
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Submitted to: Nature
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/31/2001 Publication Date: 3/29/2001 Citation: N/A Interpretive Summary: Plants respond to insect herbivory by synthesizing and releasing complex blends of volatile compounds that provide important host location cues for insects that are natural enemies of herbivores. When tobacco plants are damaged by tobacco budworm caterpillars feeding on the leaves they emit an odor during the daytime, comprised of a blend of volatile chemicals, that attracts parasites and predators, natural enemies of the caterpillars. Scientists at the Center for Medical, Agriclutural and Veterinary Entomology in Gainesville, FL, have discovered that during the night the plants in direct response to the caterpillar feeding emit a distinctly different odor from that released during the day. Furthermore, the nighttime odor repels tobacco budworm female moths and deters them from laying eggs on the plants. Plants that are mechanically damaged or not wounded do not release these odors. Thus, plants have a natural chemical defense that attracts allies during the day and repels pests at night. These results indicate that it may be possible to develop crop varieties, via plant breeding or gentic engineering, capable of defending themselves effectively against insect pests. Technical Abstract: Plants respond to insect herbivory by synthesizing and releasing complex blends of volatile compounds that provide important host location cues for insects that are natural enemies of herbivores1-3. Until now, the effect of these volatile blends on herbivore behavior has been investigated to only a limited extent4,5. The paucity of research on this subject is due in part to the assumption that herbivore induced volatile synthesis depends on photosynthesis and thus that volatile emissions occur mainly during the light phase of the photoperiod5,6. Since many moths, whose larvae are some of the most important insect herbivores, are active only at night, herbivore-induced plant volatiles were not previously considered to be temporally available as host-location cues for ovipositing females. Here we present chemical and behavioral assays showing that tobacco plants (Nicotiana tabacum) release herbivore induced volatiles during both night and day. Moreover, several volatile compounds are released exclusively at night and are highly repellent to female moths (Heliothis virescens). The demonstration that tobacco plants release temporally different volatile blends and that lepidopteran herbivores exploit induced plant signals released during the dark phase to choose appropriate sites for oviposition adds a new dimension to our understanding of the role of chemical cues in mediating tritrophic interactions. |
