Assessing the role of Syrphidae in the suppression of woolly apple aphid inVirginia, USA

Abstract: The fate of individual woolly apple aphid colonies on the branches of potted apple trees deployed in an experimental and a commercial orchard or held in a screened cage was recorded at 2-day intervals over 14 days from late May to early June, 2008, in Virginia, USA. Colonies on trees in the orchards either became extinct or were severely disrupted by predation by day 14. Two syrphid species, Heringia calcarata and Eupeodes americanus were the predominant arthropod predators recorded in colonies. Colonies on trees in the cage showed no decline, despite the presence of large numbers of the parasitoid, Aphelinus mali.