Release of Predators of the Balsam Woolly Aphid in North Carolina

摘要

The balsam woolly aphid, Chermes piceae Ratz. (Homoptera: Chermidae), was accidentally introduced into North America from Europe about 1900 (Balch 1952). The aphid is now a serious pest of Fraser fir, Abies fraseri (Pursh) Poir., in the Southern Appalachians. Since its discovery in North Carolina 1957 (Speers 1958), the aphid has killed thousands of trees annually. Fraser fir is an especially, valuable aesthetic resource along the Blue Ridge Parkway, in the Great Smoky Mountains National Park, and Mt. Mitchell State Park where it is viewed by millions of persons annually. The balsam woolly aphid may possibly be controlled with insect predators which are its natural enemies in Europe, as well as by predators that feed on closely related aphid species in other areas of the world. The first introductions of foreign insect predators to aid in control of the balsam woolly aphid in North Carolina were made in 1959 and 1960 (Amman 1961). Since then an additional 15 species of predators were tried in the field and laboratory. Two species were received from Germany and 13 species from India and Pakistan. Predators were released in the field in cloth or wire-screen cages placed around the trunks of Fraser fir trees moderately to heavily infested with the aphid. Predators tested in the laboratory were released in cages containing heavily infested fir bolts, the ends of which were placed in damp sand to maintain the bark moisture.