Non-staining fungi associated with the bark beetle Dendroctonus brevicomis (Coleoptera: Scolytidae) on Pinus ponderosa

Abstract

Three fungi—Ceratocystis nigrocarpa Davidson, an unidentified hyphomycete, and an unidentified basidiomycete—were isolated from extensive non-stained areas of sapwood of ponderosa pine infested with western pine beetle, Dendroctonus brevicomis Lec., in California. The two unidentified fungi were also present in the thoracic mycangium of the female beetle while C. nigrocarpa was found only externally on the beetle. The mycangium and its contents are illustrated. Ceratocystis minor (Hedgc.) Hunt, which was also found externally on the beetle but not in the mycangium, was isolated only from scattered patches of blue-stained sapwood. It is suggested that non-staining fungi play a role in causing the death of ponderosa pine trees attacked by D. brevicomis.