红脂大小蠹的发生和危害规律

采用标准地调查和单株调查的方法，研究了红脂大小蠹的发生和危害规律。结果表明：红脂大小蠹主要为害油松的基部和根部，多为胸径7．5cm以上、树龄30年生以上的树木，幼龄树受害很少；海拔850m以上的树木受害重，且随海拔的增高危害加重；路边树木受害最为严重，其次是山顶，林缘树木受害较轻，林内树木受害最轻；在不同坡向分布的树木，阴坡受害大于半阴坡，半阴坡大于阳坡；此外，该害虫一般侵害树势衰弱的林木，随着树势衰弱程度的增加，其危害程度加重，树体内害虫数量与树木的衰弱程度呈线性相关，其方程为Y=13．32X-16．25，此方程可以用来推断红脂大小蠹可能发生的程度。

The Generation and Damage Regulation of Red Turpentine Beetle

The generation and damage regulation of red turpentine beetle (Dendroctonus valens) are studied with the method of sample plot and tree-by-tree survey. The results show that the pests mainly damage the base and root portions of Chinese pine (Pinus tabulaeformis) with the diameter at breast height over 7.5 cm and the age over 30 years. The pests damage the trees at an elevation of over 850 m, and the higher the elevation is, the more serious the tree is damaged. The damage also varies in different environment situations: trees along roadside are most seriously damaged, and trees at the peak are more seriously damaged than in inner forest. The pests usually damage weak tree. The weaker the tree is, the more seriously it is damaged. The number of the insect pests is related to the health situation of the tree. The quarter is Y13.32X-16.25, by which the damage degree of pest can be inferred.