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Titre :
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Opposite, linear and non-linear effects of plant stress on a galling aphid
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Auteurs :
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C. Bjorkman
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Type de document :
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article/chapitre/communication
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Année de publication :
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1998
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Format :
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177-183
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Langues:
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= Anglais
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Mots-clés:
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Sacchiphantes abietis
;
Adelgidae
;
Homoptera
;
Picea abies
;
drought
;
irrigation
;
fertilization
;
gall density
;
gall size
;
Deficit hydrique
;
Stress
;
Contrainte
;
Essai exterieur
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Résumé :
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The impact of plant stress on the occurrence and performance of the gall-making aphid Sacchiphantes abietis (Homoptera: Adelgidae) was investigated by estimating the density and size of galls on experimentally stressed Norway spruce (Picea abies) trees. Plots with 25-yr-old spruce trees were treated so as to create a range of stress. Trees were exposed to an untreated control or one of the following five treatments: drought, irrigation, ammonium sulphate addition, nitrogen-free (''vitality'') fertilization and optimum fertilization with irrigation. The occurrence of galls was higher on drought-stressed trees than on trees in other treatments; Gall size varied continuously among treatments, with the largest galls being found on ''vitality''-fertilized trees and the smallest on drought-stressed trees. Mechanisms that might explain the inconsistent effects of stress on aphids are discussed. I conclude that plant stress has opposite effects on different life-stages of this galling insect and possibly on other species of gall-makers as well.
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Source :
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Scandinavian Journal of Forest Research - 0282-7581, vol. 13, n° 2
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