重庆尾巨桉林云斑天牛危害程度及影响因素分析

The Difference of Damage Degree of Batocera lineolata in Different Eucalyptus urophylla×E. grandis Plantations in Chongqing and Its Influencing Factors Research Using Factor Analysis

云斑白条天牛是尾巨桉的重要蛀干害虫,严重威胁重庆三峡库区等生态经济区的尾巨桉人工林建设.通过对重庆2个区30块不同尾巨桉人工林地云斑天牛越冬期虫情调查,分析了该虫的发生和危害情况,在此基础上利用因子分析方法研究该虫在各地发生和危害程度产生差异的原因.结果表明：云斑白条天牛对重庆尾巨桉的危害在近2年呈爆发趋势,各地发生和危害程度存在显著差异,受害株率为0-57.6%,平均为19.6%,以轻度和重度危害为主,其中最高的为九龙坡金凤镇的57.6%,虫口密度主要集中在20头/株以下,树干上以1-2 m为主.云斑天牛在各地危害与海拔和树龄存在一定相关性,虫口密度与受害树杆胸径呈显著正相关,海拔与虫口密度无相关性,海拔与受害株率呈显著负相关.因子分析结果显示,造成该虫在各地发生和危害巨大差异现象最主要原因受林地是否靠近公路、 人为扰动程度和虫口密度的差异影响,即上述三者组成的第一公因子的总方差贡献率达56%,影响程度大小依次为林地是否靠近公路〉人为扰动程度〉虫口密度;对个别林地的危害情况还需结合其他影响因素进行综合分析.

Batocera lineolata, an important stem-borer on eucalyptus, affects seriously the development of fast-growing eucalyptus plantations in the Three-Gorges-Reservoir-Area of Chongqing. In this paper, field investigations were conducted during overwintering period at 30 plantations of Eucalyptus urophylla x E. grandis in 2 districts of Chongqing, China, to assess the situations of occurrence and damage of the stem-borer. Furthermore, based on these findings, factor analysis was applied to the analysis of influencing factors of difference in the damage degree caused by the stem-borer among these eucalyptus forestlands. The results showed that the damage of B. lineolata to the eucalyptus had increasing trend of the outbreak in the last two years, and significant differences in damage de-gree among these eucalyptus forestlands, and damage rates was 0-57. 6% with an average of 19. 6, which belongs to light or serious damage degree in most forestlands. The highest damage rate was 57. 6% in Jinfeng town of Jiu-longpo district. The insect density was mainly below 20 insects/plant and the trunk was mainly 1-2 m. The dam-age of B. lineolata has a certain correlations with the altitude and tree-ages, and the insect density was significantly positive correlated with diameter of damaged trunks, and altitude has no correlation with insect density and was sig-nificantly negative correlated with damged rate of the trunks. The factor analysis showed that the first factor accoun-ted for 56% of the total variance, which means highway, artificial disturbance degree and insect density were the characteristic elements in influencing the pest occurrence in different forestlands. The sequence of influencing factors was highway〉artificial disturbance degree〉insect density. Moreover, for a special case in damaged forest, it is necessary to consider other influencing factors to give out a reasonable explanation in the damage degree of the pest in eucalyptus forestlands.