The Effect Of The Bacteria Carried By Pine Wood Nematode Bursaphelenchus Xylophilus On Its Reproduction And Development

The site of the bacteria on pine wood nematode was observed and the effect of the bacteria on the fecundity, egg hatch, and development of pine wood nematode was also researched in this paper. The main results are as follows:1. The observation on pine wood nematode with SEM and TEM showed that there are bacteria on the nematode body surface. Bacteria appeared on NB medium after surface sterilizing and triturating live nematodes, then cultivating for 16h. It confirmed that there were bacteria deep under the nematode body surface.2. The bacterium Pseudomonasfluroescens GcM5-lA strain could increase the fecundity of pine wood nematode: In the period of the observation, the mean egg number of the pine wood nematode treated with Pseudomonasfluroescens GcM5-1A strain was 45 per female, the egg number of the control group was only 2 per female.3. The bacterium Pseudomonas fluroescens GcM5-1A strain could accelerate the development rate of pine wood nematode: Pine wood nematode treated with Pseudomonas fluroescens GcM5-1A strain needs 4 days to complete one generation. However it needs 5.6 days for control. There is significant difference between Pseudomonas fluroescens GcM5-1A strain and control group by Duncan test.4. The bacterium Pseudomonas fluroescens GcM5-lA strain could promote the development of pine wood nematode: The pine wood nematodes treated with Pseudomonas fluroescens GcM5-1A strain are significantly greater than the group treated with Pantoeu sp. SH1C strain, Pseudomonas putida ZpHl-2A strain, Peptostreptococcus asaccharalyticus AH 1C strain and the control group in body length, body diameter and body volume.5. The nematode has high egg hatch rate even treated with 30% H2O2. It showed that the nematode egg had high resistance to adversity. So we can treat nematode eggs with 30% H2O2 about 10min to get aseptic nematode eggs, then we can get aseptic nematodes easily by aseptic eggs. It provided us a shortcut to get aseptic nematodes.6. New way to get nematode eggs and to separate the eggs from nematodes was found. Nematodes were put on 2% agar in a dish for 6~24h to get eggs, and live nematodes were killed by 30% H2O2 for lOmin while eggs still kept high hatch rate. Then some precise researches such as nematodes production and development, eggs hatch rate could be made possibly.Four bacteria species isolated from nematode which appeared in relatively high frequency were studied, and among the four bacteria, there are strong-pathogenic bacterium, weak-pathogenic bacterium and non-pathogenic bacterium, the result showed that only the strong-pathogenic bacterium Pseudomonasfluroescens GcM5-1A strain has consistent effect on everyobservational value, such as the number of egg production, development rate, body length, body diameter and body volume, and there is significant difference between the group treated with Pseudomonas fluroescens GcM5-1A strain and the control group.Evidences that the pathogenic bacteria carried by pine wood nematode affect the egg production and development of PWN were given. The author concluded that relationships between pine wood nematode and the pathogenic bacteria carried by PWN is mutualism, the bacteria live on PWN's body surface, the mutual relationship is formed through long time coevolution. It is important to further clarify the mechanism of pine wilt disease.