European Journal of Entomology (2000) 97, 545-550

G. Petersen, C. Matthiesen, W. Francke and U. Wyss (2000)
Hyperparasitoid volatiles as possible foraging behaviour determinants in the aphid parasitoid Aphidius uzbekistanicus (Hymenoptera: Aphidiidae)
European Journal of Entomology 97 (4), 545-550
Abstract: The foraging behaviour of individual females of Aphidius uzbekistanicus Luzhetski (Hymenoptera: Aphidiidae) on oat plants with one colony of the grain aphid Sitobion avenae F. (Homoptera: Aphididae) was examined in laboratory experiments. Patch time allocation was analysed under semi-natural conditions when individual hyperparasitoid females, Alloxysta victrix Westwood (Hymenoptera: Alloxystidae) or their volatiles 6-methyl-5-hepten-2-one or a mixture of iridoid substances soaked on vermiculite dummies were present simultaneously. Patch residence times of foraging primary parasitoid females were significantly reduced in all analysed treatment groups. Attack numbers on aphids and resulting aphid mummies were also significantly reduced. The presence of hyperparasitoids or their volatiles had no influence on the proportion of time spent engaged in different behaviour by the primary parasitoid. After encounters with hyperparasitoid females or vermiculite dispensers, which had been soaked with the synthetical iridoids, A. uzbekistanicus females changed their behaviour more frequently, and they left the aphid colony at a higher rate than in the controls, where dispensers had been soaked with only pure pentane: The identification of the associated iridoidsubstances, produced in the hyperparasitoid mandibular glands, is briefly described and their biological significance is discussed.
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Database assignments for author(s): Urs Wyss

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.
	Sitobion avenae	Oat (Avena sativa)
Aphidius uzbekistanicus (parasitoid)	Sitobion avenae	Oat (Avena sativa)