青杨楔天牛对杨树危害的研究

定量研究青杨楔天牛对白城杨的危害表明：寄生直径小于0.5cm的枝梢，侵入初期92.2%枯萎风折；寄生直径小于1.0cm的枝梢，侵入后期11.5%风折，成虫出孔后87.4%的寄生枝梢干枯风折。青杨楔天牛形成的虫瘿对枝梢的连年生长量影响时间长，影响量大。每主梢有1只和2只虫瘿其第1、2、3年连年生长量分别减少28.3%、16.4%、9.8%和42.0%、28.9%、17.2%。每侧枝上有1只和2只虫瘿其第1、2、3年连年生长量分别减少21.7%、12.1%、6.3%和34.8%、22.8%、13.8%。

Study on Saperda populnea Harming Populus × xiaozhuarica cv. ‘Baicheng'

Saperda populnea is one of the important pests on poplar's branch and top in Jilin Province. The damage of this insect to Populus × xiaozhuarica cv.'Baicheng' was studied. This pest parasites on the branches with diameter less than 0.5 cm. In the early stage,92.2% of the branches will be withered and wind broken.In the late stage,11.5% of the branches with diameter less than 1 0 cm will be wind broken. When the adult insect emerges,87.4% of the invaded branches will be withered and wind broken.The gall formed by S. populnea has serious influence on the consecutive increments of branch and top. If there is one or two galls on the top of a main branch,the increment of the branch will decrease by 28.3%,16.4% and 9.8%, 42.0%, 28.9% and 17.2% respectively in the first, second and the third year. If there is one or two galls on the top of a lateral branch,the increment will decrease by 21.7%, 12.1% and 6.3%, 34.8%, 22.8% and 13.8% respectively in the first, second and the third year.