The Influence of Nematode Parasites and Associates on Bark Beetles in the United States

Abstract

Bark beetles destroy many mil1ions of board feet of timber in the United States each year. Detailed studies have been made, or are being made, on the biology and ecology of the more important economic species. Little is known, however, of the role of nematodes in the ecology of these insects. Nematodes were acknowledged as parasites of bark beetles nearly 75 years ago, when Von Linstow (1880) published on the presence of the genus Allantonema in the body cavity of Ips typographus L. The writer has recovered the parasites from most species of bark beetles examined from various sections of the United States. Many species are infested with two or three separate genera. In numerous cases these parasites appear to be host specific. They have been taken from the abdominal cavities of Orthotamicus ornatus Swaine, which measures approximately 2 mm. in length, and from Dendroctonus valens LeConte and Dendroctonus terebrans (Olivier), measuring up to 9 mm. long. The adult parasites range in length from ½ mm. to 7 mm. They have been collected from entomophagous associates such as Corticeus , and from Coeloides dendroctoni Viereck, a braconid parasite of various species of Dendroctonus and Ips .