Journal of Chemical Ecology (2002) 28, 1717-1732

N. Neveu, J. Grandgirard, J.P. Nenon and A.M. Cortesero (2002)
Systemic release of herbivore-induced plant volatiles by turnips infested by concealed root-feeding larvae Delia radicum L.
Journal of Chemical Ecology 28 (9), 1717-1732
Abstract: When attacked by herbivorous insects, many plants emit volatile compounds that are used as cues by predators and parasitoids foraging for prey or hosts. While such interactions have been demonstrated in several host-plant complexes, in most studies, the herbivores involved are leaf-feeding arthropods. We studied the long-range plant volatiles involved in host location in a system based on a very different interaction since the herbivore is a fly whose larvae feed on the roots of cole plants in the cabbage root fly, Delia radicum L. (Diptera: Anthomyiidae). The parasitoid studied is Trybliographa rapae Westwood (Hymenoptera: Figitidae), a specialist larval endoparasitoid of D. radicum. Using a four-arm olfactometer, the attraction of naive T. rapae females toward uninfested and infested turnip plants was investigated. T. rapae females were not attracted to volatiles emanating from uninfested plants, whether presented as whole plants, roots, or leaves. In contrast, they were highly attracted to volatiles emitted by roots infested with D. radicum larvae, by undamaged parts of infested roots, and by undamaged leaves of infested plants. The production of parasitoid-attracting volatiles appeared to be systemic in this particular tritrophic system. The possible factors triggering this volatile emission were also investigated. Volatiles from leaves of water-stressed plants and artificially damaged plants were not attractive to T. rapae females, while volatiles emitted by leaves of artificially damaged plants treated with crushed D. radicum larvae were highly attractive. However, T. rapae females were not attracted to volatiles emitted by artificially damaged plants treated only with crushed salivary glands from D. radicum larvae. These results demonstrate the systemic production of herbivore-induced volatiles in this host-plant complex. Although the emission of parasitoid attracting volatiles is induced by factors present in the herbivorous host, their exact origin remains unclear. The probable nature of the volatiles involved and the possible origin of the elicitor of volatiles release are discussed.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Julie Grandgirard, Anne Marie Cortesero

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Delia radicum	Brassica - other species
Trybliographa rapae (parasitoid)	Delia radicum	Brassica - other species