Studies On The Pathogenicity Of The Bacteria Carried By Pine Wood Nematode And The Relationship Between The Bacteria And The Nematode

The article studied the relationship between pine wood nematode and bacteria, compared their ability of carrying bacteria and determined bacteria's pathogenicity. The main results are as follow:1. The bacteria carried by different nematodes are not same. The bacteria isolated from the surface of B. xylophilus were Pseudomonas fluorescens and Flavimon oryzihabitans. The bacterial of Pseudomonas fluorescens with a high percentage were considered as main bacterium on the body of pine wood nematode. The main bacterium isolated from Bursaphelenchus mucronotus were identified as Xanthomonas maltophilia. The main bacterium isolated from Rhabditida and from Aphelenchoides sp. were identified as Enterobacter aerogenes and Xanthomonas maltophilia respectively.2. The virulence tests indicated that bacterial of Pseudomonas fluorescens has the most virulent and Enterobacter aerogenes is nontoxic. The other bacteria isolated from different nematodes have virulence to a certain extent.3. The results of artificial inoculation experiments indicated that the seedling wilting and callus browning occur while inoculated with the mixed suspension of nematode and bacterium, but not occur while inoculated with nematode or bacteria individually. This revealed that the bacteria play a decisive role in the development of wilting, which give the opinion a strong evidence that pine wilt disease was a disease complex involving nematode and bacteria.4. Studies on the relationship between pine wood nematode and bacteria indicated that living nematode are favorable for the propagation of the bacteria and the pine wood nematode was better than others. On the other hand, the bacteria are favorable for the propagation of pine wood nematode. The propagation ability of pine wood nematode was strongly stimulated when the bacteria had been mixed with the aseptic pine wood nematode.5. The number of bacteria adhered to the boby surfaces of aseptic nematodes body are different. The number of bacteria adhered to the aseptic pine wood nematode was about 250 cells, which was larger than Bursaphelenchus mucronatus, Rhabditida and Aphelenchoides sp.6. Body surface of pine wood nematode is covered with a layer of viscous polysaccharose. Quantitative analysis indicated that the amount of solublepolysaccharose is about 59.17 g every 10 thousand nematodes, which was more than the other nematodes. The soluble polysaccharose was partly lost after asepsis.7. Aseptic pine wood nematode was inoculated at the 10 years old black pine in the field. Although the 3 contrast pines inoculated with wild pine wood nematode were died after 9 month later, most treatment pines were still healthy. Reisolation from the healthy pines indicated that only pine wood nematodes can be separated, and the nematodes were all aseptic. It proved that only pine wood nematode can not lead to the pine wilting, and the pines would wilt only the bacteria existing and carried by pine wood nematode.