Journal of Chemical Ecology (1995) 21, 761-774

Maarten van Helden, Hanneke P.N.F. van Heest, Teris A. van Beek and W. Freddy Tjallingii (1995)
Development of a bioassay to test phloem sap samples from lettuce for resistance to Nasonovia ribisnigri (Homoptera, Aphididae)
Journal of Chemical Ecology 21 (6), 761-774
Abstract: The Nr-gene-based resistance of lettuce to the aphid Nasonovia ribisnigri (Mosley) has previously been shown to be located in the phloem. Since chemical analyses of the phloem sap had shown no differences between resistant and susceptible lines, a bioassay was developed in order to test samples from resistant and susceptible plants on aphid feeding. For this, whole-plant extracts, honeydew, and EDTA-collected phloem extracts were obtained, and a sensitive bioassay was developed using EDTA samples. The EDTA was removed, and samples were added to a simple sucrose solution or to a complex artificial diet and presented in a choice situation comparing extracts from resistant and susceptible plants. EDTA-collected phloem sap samples from susceptible plants were preferred to those from resistant plants. The resistance is probably based on a feeding deterrent activity of the phloem sap in the resistant plant.
(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): W. Fred Tjallingii, Maarten Van Helden

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Nasonovia ribisnigri	Lettuce (Lactuca)