Journal of Chemical Ecology (2012) 38, 348-360

Islam S. Sobhy, Matthias Erb, Awad A. Sarhan, Monir M. El-Husseini, Nasser S. Mandour and Ted C.J. Turlings (2012)
Less is more: Treatment with BTH and laminarin reduces herbivore-induced volatile emissions in maize but increases parasitoid attraction
Journal of Chemical Ecology 38 (4), 348-360
Abstract: Chemical plant strengtheners find increasing use in agriculture to enhance resistance against pathogens. In an earlier study, it was found that treatment with one such resistance elicitor, BTH (benzo-(1, 2, 3)-thiadiazole-7-carbothioic acid S-methyl ester), increases the attractiveness of maize plants to a parasitic wasp. This surprising additional benefit of treating plants with BTH prompted us to conduct a series of olfactometer tests to find out if BTH and another commercially available plant strengthener, Laminarin, increase the attractiveness of maize to three important parasitic wasps, Cotesia marginventris, Campoletis sonorensis, and Microplitis rufiventris. In each case, plants that were sprayed with the plant strengtheners and subsequently induced to release volatiles by real or mimicked attack by Spodoptera littoralis caterpillars became more attractive to the parasitoids than water treated plants. The elicitors alone or in combination with plants that were not induced by herbivory were not attractive to the wasps. Interestingly, plants treated with the plant strengtheners did not show any consistent increase in volatile emissions. On the contrary, treated plants released less herbivore-induced volatiles, most notably indole, which has been reported to interfere with parasitoid attraction. The emission of the sesquiterpenes (E)-β-caryophyllene, β-bergamotene, and (E)-β-farnesene was similarly reduced by the treatment. Expression profiles of marker genes showed that BTH and Laminarin induced several pathogenesis related (PR) genes. The results support the notion that, as yet undetectable and unidentified compounds, are of major importance for parasitoid attraction, and that these attractants may be masked by some of the major compounds in the volatile blends. This study confirms that elicitors of pathogen resistance are compatible with the biological control of insect pests and may even help to improve it.
(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): Ted C.J. Turlings

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.
	Spodoptera littoralis	Maize/corn (Zea mays)
Campoletis sonorensis (parasitoid)
Cotesia marginiventris (parasitoid)	Spodoptera littoralis
Microplitis rufiventris (parasitoid)