Status of Imported and Native Predators of the Balsam Woolly Aphid on Mt. Mitchell, North Carolina

摘要

On the Mt. Mitchell area during the summer of 1968, 20 stands of Fraser fir, Abies fraseri (Pursh) Poir., infested by the balsam woolly aphid, Adelges (piceatx), were examined for native and previously imported predators of the aphid. Laricobius erichsonii Bosenhauer (Coleoptera: Derodontidae) was the only foreign predator located, and it occurred on 30 percent of the sites sampled. In terms of distribution, this predator ranked below the native species, Allothrombium mitchelli Davis (Acarina: Trombidiidael, Bdellidae) (Acarina), and Hemerobius spp. (Neuroptera: Hemerobiidaef. Aphidecta obliterata) L. 1 (Coleoptera: Coccinellidae) was not found at sites where it waspreviously released nor at other sites. Its survival, in the face of naturally diminishing populations of the aphid, is regarded as tenuous at best.