Abstract: In order to study the hazard degree of Hemiberlesia pitysophila Takagi to different strains of Pinus massoniana, and reveal the direct and indirect damage reflected by indicators of the number of insects, six indicators consisting of population density etc. in a selected test forest was investigated, and one-way path analysis method was adopted. The results showed that the most positive indicators of direct impact were population density and the ratio of damaged needle, but the largest negative indicator of indirect impact just was the ratio of damaged needle. Generally speaking, the important indicators reflecting the increasing degree of damage were successively as follows: population density, the ratio of infested slash pine trees, the number of the breeding insects in a certain time, the survival rate of the 1st instar larvae, the survival rate of the 2nd instar larvae, the ratio of damaged needle. The 28 masson pine strains surveyed could be divided into four categories, of which no. 390 and no. 439 strains were the most damaged, while no. 458 and no. 469 strains were the least damaged. The analyzed results were basically coherent and in line with the reality. Therefore, the results provided an important reference to select study indicators and the selecting and breeding of insect-resistant pedigree. One-way path analysis method, with a certain degree of rationality and innovation in theory, was feasible in practice and worthy of research and popularization.

Key words: Hemiberlesia pitysophila, Pinus massoniana, strain, hazard degree, one-way path analysis