Constant association of ophiostomatoid fungi with the bark beetle Ips subelongatus invading Japanese larch logs

Ceratocystiopsis, Ceratocystis, Grosmannia, and Ophiostoma species were isolated from Ips subelongatus and beetle-infested Japanese larch logs collected at several areas in central and northern Honshu Island, Japan, to determine constant associates of I. subelongatus. Ceratocystiopsis minuta, two species of Ceratocystis, three species of Grosmannia, and four species of Ophiostoma were isolated. Of the fungi isolated in the present study, G. laricis, O. brunneociliatum, and O. piceae were constant associates of the beetles. Ceratocystis fujiensis, Ceratocystiopsis minuta, and Ophiostoma sp. F were occasionally isolated with high frequencies of occurrence but were not consistent associates. Ceratocystis fujiensis was most often isolated as the leading fungal invasion in the sapwood of Japanese larch logs invaded by I. subelongatus, confirming that the fungus acts as a primary invader of sapwood in beetle-attacked logs.