Influence of the hyperparasitoid Dendrocerus carpenteri on the reproduction of the grain aphid Sitobion avenae

Abstract

1. Alate S. avenae (F.) reproduced earlier and produced more offspring in the vicinity of Dendrocerus carpenteri (Curtis) females than control aphids without neighbouring hyperparasitoids. 2. This effect was evident only during the first 6 days of the aphid's reproduction period and did not affect the physiological condition of the aphids or their offspring. 3. Virgin hyperparasitoid females had a stronger influence on the reproduction rate of the aphids than did mated females, probably due to an unidentified emitted volatile sex pheromone.