Journal of Chemical Ecology (2003) 29, 261-274

Robert Glinwood, Jan Pettersson, Elham Ahmed, Velemir Ninkovic, Michael Birkett and John Pickett (2003)
Change in acceptability of barley plants to aphids after exposure to allelochemicals from couch-grass (Elytrigia repens)
Journal of Chemical Ecology 29 (2), 261-274
Abstract: The response of the bird cherry-oat aphid, Rhopalosiphum padi, to barley plants was investigated following exposure of the plants to root allelochemicals from the aggressive weed couch-grass, Elytrigia (Agropyron) repens. Plants were treated either with root exudates from living couch-grass plants or with previously identified couch-grass root compounds [5-hydroxyindole-3-acetic acid, DL-5-hydroxytryptophan, L-5-hydroxytryptophan hydrate, and 6-hydroxy-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid (carboline)] either separately or in mixtures. In choice and no-choice settling tests, aphid acceptance of barley plants was significantly reduced following treatment with root exudates, and the carboline when tested alone or in combination with the other compounds. In contrast, the other compounds without the carboline were less active in reducing aphid acceptance. In a probing bioassay, individual substances were either neutral or stimulatory to aphids, indicating that the reduced settling was probably not due to direct effects on aphids, but rather due to effects on the plant. This was confirmed in olfactometer assays, in which aphids were repelled by odors from barley plants following treatment with a mixture containing all four chemicals.
(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): Robert T. Glinwood, Velemir Ninkovic, Michael A. Birkett, John A. Pickett

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Rhopalosiphum padi	Barley (Hordeum vulgare)
	Elymus repens (weed)	Barley (Hordeum vulgare)