Bursaphelenchus xylophilus virulence in response to increase of Pinus thunbergii resistance

松材线虫无性系对松材线虫的抗性水平不同。接种线虫后，抗病母树的生根插条成活率高于感病母树。越短越细的黑松插条生根能力越强。虽然我用不同抗性水平的松枝和苗木选择了线虫的致病力，但松树的抗性水平并不影响所选线虫的致病力。从温州卫山台市的抗病林和感病林中提取的线虫分离物显示出几乎相同的毒力水平。

The resistant level against Bursaphelenchus xylophilus was different among P. thunbergii clones. The rooted cuttings from resistant mother trees showed higher survival rate than that from susceptible mother trees after nematode inoculation. The shorter and thinner Pinus thunbergii cuttings tended to show better rooting ability. Although I selected nematode virulence using pine cuttings and seedlings with different resistant level, the resistant level of pines did not affect the virulence of the selected nematodes. Nematode isolates extracted from resistant forest and susceptible forest in Satsumasendai City showed almost the same level of virulence.