Abstract: To understand the relationship between stand factors of Pinus densiflora pure forest and Cephalcia kunyushanica occurrence, and thus to provide theoretical guidance for P. densiflora pure forest management as well as the prevention and control of C. kunyushanica, we investigated seven stand indices of stand density, canopy cover, herb coverage, tree height, height under branch, diameter at breast height (DBH) and crown size as well as the nest number of C. kunyushanica in P. densiflora pure forests with relatively consistent stand age (34±2 years old) in the Kunyushan Mountains. The plots were divided into four groups according to the distribution range of the pest severity index (PSI). The differences of stand factors in four groups were examined by means of variance analysis and multiple comparison. Stepwise regression was used to select key factors affecting C. kunyushanica. The relationship between the critical stand factors and the PSI was further clarified by partial correlation analysis and oneway ANOVA. The results showed that all the seven stand factors were significantly different among the four groups. Crown size, height under branch and stand density were the key factors affecting the PSI among the seven factors following results from stepwise regression. Then, the prediction equation of pest severity index was established. The effects of crown size and height under branch on PSI were significant and positive (P<0.01), while stand density had a negative effect (P<0.01). However, the key factors affecting the insect pest index may be inconsistent in different forests. Forest structure should be adjusted according to the critical factors to achieve the goal of controlling the epidemic of insect pests.

Key words: cotton, flowering and bolling stage, drought and waterlogging, boll, carbohydrate, biomass accumulation.