紫胶虫种群死亡率探讨与计算方法改进

A Probe into the Mortality of Lac Insect Population and Improvement of the Mortality Formula

对紫胶蚧夏代的7种寄主植物生长情况及紫胶蚧死亡状况进行了研究。结果表明:不同寄主植物生长速度不一样,到紫胶蚧世代末,不同寄主植物未被紫胶蚧寄生枝条的面积增长值为30%～50%,被紫胶蚧寄生枝条面积增长值为15%～40%;紫胶蚧寄主植物枝长和枝径的增长速度差异为5倍;紫胶蚧寄主植物在紫胶蚧世代初(前45d)的生长量约占整个世代生长量的15%,而在紫胶蚧成虫期的生长量占整个世代中的生长量的85%。紫胶蚧在幼虫期死亡率较高,到世代末,紫胶蚧累计死亡率达到90%以上。目前的紫胶虫死亡率计算公式是:M=(d-d')/d,该公式没有考虑紫胶虫寄主植物的生长对紫胶虫死亡率统计的影响,本研究结合紫胶虫寄主植物的生长情况,采用校正系数C对紫胶虫死亡率计算公式进行了改进,新的公式为:M=(d-Cd )/d,并对利用校正系数改进原统计方法进行了探讨。

Field research was conducted on 7 host tree species and lac insect population dynamic of lac insect during estival generation. The results are as follow: Different host tree has different growing speed, the increment of the area of branch without lac insect is up to 30%～50% among different host trees at the end of lac insect life history, otherwise, the increment of the area of branch with lac insect is up to 15%～40%; the branch has different growing speed in different orientation, the longitude growth is 5 times faster than transverse growth; the host trees of lac insect grow slowly at the beginning of lac insect life history, but grow fast during lac insect adult period. Differently aged branches of the same host tree have different growing speed. Younger branches grow faster than order ones. Host tree of lac insect grows slower during winter than that during estival. Lac insect has higher mortality in larvae stage, and the total mortality of lac insect is more than 90%. Former formula for lac insect mortality M=(d-d')/d, ignores that host tree growth has influence on the statistical result of lac insect population. According to the truth that host tree of lac insect grows continuously during the whole life cycle of lac insect, an improved new formula to count mortality of lac insect M=(d-Cd')/d is proposed.