THE RESPONSES OF PRAON SPP PARASITOIDS TO APHID SEX-PHEROMONE COMPONENTS IN THE FIELD

In autumn 1991, aphid parasitoids of the genus Praon (Hymenoptera; Bra conidae) were caught in water traps with lures containing synthetic ap hid sex pheromone components at three sites in England and one in Germ any. At two of the English sites and at the German site, the traps wer e placed in winter cereal fields whilst the third English site was in woodland. Three species were caught, P. volucre, P. dorsale and P. abj ectum. Those caught in cereal fields were almost entirely P volucre, w hilst P dorsale dominated at the woodland site. Of the known aphid sex pheromone components, the most effective lure was the (+)-(4aS,7S,7aR )-nepetalactone. Nepetalactone traps placed at the woodland site in sp ring and summer caught few Praon females, and attraction may be confin ed to the autumn, when sexual female aphids are present in the held. M ale parasitoids did not respond to the aphid pheromones at any time, a lthough they were caught in suction traps operated at the woodland sit e during the autumn. At the cereal sites height had a significant infl uence on the efficiency of the pheromone traps, those placed just abov e the crop canopy being most effective. There was no evidence that any other genus of parasitoid responded to aphid sex pheromones at these sites.