Comparison of geographical isolates of Bursaphelenchus tadamiensis (Tylenchomorpha: Aphelenchoididae) with remarks on its preferred habitat

Bursaphelenchus tadamiensis, which was initially isolated from a stag beetle, Dorcus striatipennis, collected from sap flow of Quercus crispula in Fukushima, north-eastern Japan, was re-isolated three times from sap flow of Quercus spp. in western Japan. The re-isolated populations were mostly morphologically consistent with the type population, but the male bursal flap showed high variations in the newly collected populations. Molecularly, the type and new populations showed differences in the internal transcribed spacer region of ribosomal DNA and mitochondrial cytochrome oxidase subunit I gene, suggesting that the species is genetically divided into several local populations. The isolation pattern of B. tadamiensis, i.e., the species was initially isolated from sap flow-associated beetles and subsequently isolated from sap flow, suggests that the species prefers and is adapted to the sap flow environment as its habitat.