Seasonal changes in the nematode fauna in pine trees killed by the pinewood nematode, Bursaphelenchus xylophilus

Abstract

The seasonal changes in the number of free-living nematodes and the pinewood nematode (PWN), Bursaphelenchus xylophilus, in 15-year-old Japanese black pine (Pinus thunbergii) trees killed by the PWN were determined. Fifteen species of nematodes were isolated, i.e. one species, each of Mononchida and Plectidae, two species, each of Monhisterida, Rhabditida and Tylenchida, three species of Bursaphelenchus including the PWN, and four species of Diplogasterida. The PWN and one species of Diplogasterida were the most prevalent nematodes isolated. The numbers of PWNs decreased from August to December, 2004, but then increased in February, 2005, then decreased again until June, 2005. During the experimental period the population changes of the Diplogasterida nematode mimicked those of the PWN, however, correlations between the numbers of the two nematodes varied considerably both among trees and seasons. Both the PWN and the Diplogasterida nematode were more abundant around the pupal chambers of the vector beetle, Monochamus alternatus, than elsewhere in the tree wood. Jpn. J. Nematol. 36 (2), 87-100 (2006). Key words: pine wilt disease, nematode community, population dynamics.