Study On The Population Dynamics Of Hemiberlesia Pitysophila Takagi

1.The population fluctuation of Hemiberlesia pitysophila Takagi has four peaks. Taking placing in April , July, October and December respectively. The surivival probability dynamics displays four peaks too, occuring in middle ten days of-April, latter ten days of May, Octobcr to December. The population density of Hemiberlesia pitysophila Takagi in the early half of the year is most than that in later half of the year. Temperature is a key factor effecting the mortality rate of the insect. It effect the population' s survive rate by acting on 1st instar larvae.2. Distribution of Hemiberlesia pitysophila Takagi is different between on the new tips and old ones. The population density on the new tips reached the same as on old tips in 105 days since the first instar was found on the new tips. The population density on old tips is much higher than that on new tips remarkably. The density of 2st instar larvae undifferentiated is the highest among the instars. The mortality rate of 1st instar larvae is higher than the others on new tips but contrary on old tips.3.The distribution patterns of Hemiberlesia pitysophila Takagi belongs to high aggregation. It' s changing is not notable. It is only the highest aggregated distribution in December. In the total, the distribution patterns of Hemiberlesia pitysophila Takagi in new tips and olds all belongs to aggregated distribution. But it is higher in old tips than new ones.4. Establish the natural population lifetable by synthesizing A. A. Berryman methods. And analysis it's key factors by Exclusion Indexof Population Control, EIPC, it showed that the key factor were natural mortality. And the 1st instar larvae is key stage. The index of population tendency was 4.12,it indicated population of Hemiberlesia pitysophila Takagi is expanding.5. By means of investigation of the chest measurement of Pinus massoniana, population density of Hemiberlesia pitysophila Takagi and the percentage of death tipS etc.in the middle-aged pine forest. The research results indicated: there are no existed significant difference of Hemiberlesia pitysophila Takagi population density among different chest measurement pine tree, but its percentage of death tips existed significant difference, which the percentage of death tips in chest measurement 40~50cm pine tree was higher than that others significantly, so the competition ability to nutrition and space didn' t incarnated the resistance to the pest; there existed a trend of pine tree damaged more severely with the tree' s chest measurement increasing in middle-aged pine forest. By analysis of correlation, there are no existed significant difference of the pest population density among different chest measurement pine tree, but its percentage of death tips existed significant difference, And it show that the formula of the relation between the percentage of death tips and percentage of death tips: y=3. 7821x-30. 0479 (y express percentage of death tip, and x express chest measurement). The difference of the pest density among different layer in pine tree were not significant.