INSECTS ASSOCIATED WITH BUTTERNUT AND BUTTERNUT CANKER IN MINNESOTA AND WISCONSIN

Butternut, Juglans cinerea, is being killed throughout its native rang e in North America by the fungus Sirococcus clavigignenti-juglandacear um. In addition to rain splashed spores, it is thought that the fungus may have spread over long distances to infect widely scattered butter nut by insect vectors. During surveys in 1995 and 1996 we found severa l insect species in close association with diseased butternut trees, a nd spores of S. clavigignenti-juglandacearum were isolated in pure cul ture from the bodies of some of these insects. Potential insect vector s were species in the coleopteran genera Eubulus (Curculionidae), Laem ophlaeus (Laemophloeidae), and Glischrochilus (Nitidulidae). Because s everal insect species become contaminated with fungal spores, further study is needed to determine if any of these insects might transmit th e fungus to healthy trees and thereby infect them.