油松毛虫的空间分布型及抽样技术

采用Iwao(1968—1977)的(m)对m的回归方法以测定油松毛虫Dendrolimus tabulaeformis Tsai et Liu越冬幼虫、茧、卵块的空间分布型, 并用不同的抽样方法比较了抽样精确度.油松毛虫越冬幼虫, 茧、卵块在油松人工林内都呈聚集分布.幼虫和茧分布的基本成分是双重个体群.卵块分布的基本成分是卵块个体, 其遵从有一公共K值的负二项分布.抽样方法:当越冬幼虫在低密度情况下以单对角线法最佳, 茧在中密度情况下, 卵块在中低密度条件下均以双对角线法为最佳.

SPATIAL PATTERNS OF THE PINE CATERPILLAR POPULATIONS AND THEIR SAMPLING METHODS

Spatial patterns for egg-masses, smali larvae and cocoons of the pine caterpillar Dendroli-nus tabulaeformis are analyzed by means of Iwao's method of regression of mean crowding (m) on mean density (m) from data obtained in Beijing. All indices indicate that the egg-masses, small larvae and cocoons are of the aggregation pattern. The basie components of the egg-masses are individuals which fit to negative binomial series with a coramon k(k=-1.0107). The hasic cornponents of smali larvae and cocoons occur as loose double clumps, in which the mean size of samll colonies of small larvae were 19 to 22 square meters and that of largc clumps were 47 to 66 square meters and thc mean size of smali colonies of cocoons were 19 to 28 square mciers and that of large clumps were 63 to 99 square meters. The distribuition of the chunps was aggregative and that of the colonies within largc clumps was regular. The intracolonial distribution was random. Several simpling methods have been compared by the averaged crrors. The results show that for latvar in carlies instars with low density the single diagonal method is the best, for cocoons with mediure density and the egg-masses with medium and low densities the double diagonal method is the best.