间伐修枝措施对松突圆蚧的控制效果

4 a的调查研究结果表明：不同强度的修枝间伐措施对松突圆蚧虫口密度和雌蚧死亡率均有一定的影响,从总体上看,松突圆蚧虫口密度减退率和雌蚧死亡率随着修枝间伐强度的增大而增大.从时间上看,间伐控制害虫危害作用限于2 a左右,间伐2 a后虫口密度和雌蚧死亡率均不存在显著差异;从间伐强度上看,对照与30%以上的间伐强度（C、D、E）之间、间伐强度25%（B）与40%（E）之间虫口密度有显著差异,其他两两之间没有显著差异;35%以上的间伐强度（D、E）与对照之间、间伐强度25%（B）与40%（E）之间雌蚧死亡率有显著差异,其他两两之间没有显著差异.

Control effects of pruning and thinning on Hemiberlesia pitysophila

Four years of investigation showed that pruning and thinning helped to decrease Hemiberlesia pitysophila population density and increase the mortality of its female adults and the effect increased with pruning and thinning intensities. The control effect could only be seen within the first 2 years and after that it was not that significant. Pruning and thinning at the intensity of 30%, 35% or 40% all could decrease H.pitysophila population density but no significant differences could be found among the 3 intensities. Similarly, pruning and thinning at the intensity of 35% or 40% both could increase the mortality of H.pitysophila female adults but no significant difference existed between the 2 densities.