Within-wood Spatial Dispersion of the Pinewood Nematode, Bursaphelenchus xylophilus

Pinewood nematode, Bursaphelenchus xylophilus (Steiner &Buhrer) Nickle, spatial dispersion was determined in Scots pine, Pinus sylvestris L., bolts infested with the pine sawyer beetle, Monochamus carolinensis (Olivier) and in bolts without M. carolinensis. According to Taylor's power law and Green's index of dispersion, nematode dispersion was aggregated in both sets of bolts. The degree of aggregation did not differ significantly between beetle-infested and noninfested bolts, suggesting that the presence of M. carolinensis does not affect nematode dispersion within a bolt. Nematode population densities differed radially in bolts not infested with pine sawyers, but in a nonregular pattern. Moisture content of the bolts was correlated with population density of B. xylophilus, suggesting that nematode aggregates occur in areas of high moisture content.