Relationship between the pathogenicity of the pine wood nematode, Bursaphelenchus xylophilus, and phenylacetic acid production.

Phenylacetic acid (PA), a toxin produced by three strains of bacteria accompanying the pine wood nematode, Bursaphelenchus xylophilus, was found to be formed in a culture of the nematode. An animal nutrient, nutrient broth (NB) medium, was more suitable for PA production of the accompanying bacteria than a vegetable nutrient, potato sucrose malt extract (PSM) medium. It is presumed that dead nematodes in the PSM medium provided the bacteria with nutrient for PA production. In the culture of virulent isolate OKD-3, more PA was detected than in that of less-virulent isolate OKD-1. PA production of the accompanying bacteria can dominate the pathogenicity of the nematode.