Biological control of woolly apple aphid by Aphelinus mali in an integrated fruit production programme in Nelson

Woolly apple aphid Eriosoma lanigerum (Hausmann) populations were monitored at the Appleby Research Orchard near Nelson (1994/1996) in two apple cultivars as part of an experimental Integrated Fruit Production programme which included the insect growth regulator insecticide tebufenozide. The aphid population increased dramatically during the first season in one cultivar ('Sturmer Pippin') from mid February and reached 90% shoot infestation by late summer. Parasitism of the aphid by the specific endoparasitoid, Aphelinus mali (Haldeman), was first recorded in late March 1995 and peaked at 13% by the end of April 1995 when monitoring ceased. In the second season the parasitoid was present from early summer and >80% parasitism was recorded by late April 1996. Aphid control was achieved without the need for specific aphicide sprays. The results indicate the potential for biological control of woolly apple aphid by A. mali within a selective insecticide programme.