Journal of Chemical Ecology (2006) 32, 1897-1909

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Michael Rostás, Jurriaan Ton, Brigitte Mauch-Mani and Ted C.J. Turlings (2006)
Fungal infection reduces herbivore-induced plant volatiles of maize but does not affect naïve parasitoids
Journal of Chemical Ecology 32 (9), 1897-1909
Abstract: Plants attacked by insects release volatile compounds that attract the herbivores' natural enemies. This so-called indirect defense is plastic and may be affected by an array of biotic and abiotic factors. We investigated the effect of fungal infection as a biotic stress agent on the emission of herbivore-induced volatiles and the possible consequences for the attraction of two parasitoid species. Maize seedlings that were simultaneously attacked by the fungus Setosphaeria turcica and larvae of Spodoptera littoralis emitted a blend of volatiles that was qualitatively similar to the blend emitted by maize that was damaged by only the herbivore, but there was a clear quantitative difference. When simultaneously challenged by fungus and herbivore, the maize plants emitted in total 47% less of the volatiles. Emissions of green leaf volatiles were unaffected. In a six-arm olfactometer, the parasitoids Cotesia marginiventris and Microplitis rufiventris responded equally well to odors of herbivore-damaged and fungus- and herbivore-damaged maize plants. Healthy and fungus-infected plants were not attractive. An additional experiment showed that the performance of S. littoralis caterpillars was not affected by the presence of the pathogen, nor was there an effect on larvae of M. rufiventris developing inside the caterpillars. Our results confirm previous indications that naïve wasps may respond primarily to the green leaf volatiles.
(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): Michael Rostas, Jurriaan Ton, Ted C.J. Turlings, Brigitte Mauch-Mani

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Spodoptera littoralis Maize/corn (Zea mays)
Exserohilum turcicum Maize/corn (Zea mays)
Cotesia marginiventris (parasitoid) Spodoptera littoralis
Microplitis rufiventris (parasitoid) Spodoptera littoralis