Hyperparasitoid volatiles as possible foraging behaviour determinants in the aphid parasitoid Aphidius uzbekistanicus (Hymenoptera: Aphidiidae)

• Main Authors: Gert PETERSEN, Christin MATTHIESEN, Wittko FRANCKE, Urs WYSS
• Format: Article
• Language: English
• Published: Institute of Entomology, Biology Centre, Czech Academy of Science 2000-12-01
• Series: European Journal of Entomology
• Subjects: foraging behaviour; aphidiidae; aphidius uzbekistanicus; hyperparasitoids; alloxysta victrix; volatiles; 6-methyl-5-hepten-2-one; trans-fused iridoids; iridomyrmecin; dihydronepetalactone
• Online Access: https://www.eje.cz/artkey/eje-200004-0017_Hyperparasitoid_volatiles_as_possible_foraging_behaviour_determinants_in_the_aphid_parasitoid_Aphidius_uzbekist.php

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 iridoid substances, produced in the hyperparasitoid mandibular glands, is briefly described and their biological significance is discussed.