SPATIAL DISTRIBUTION PATTERNS OF THE PINE CATERPILLAR(DENDROLIMUS PUNCTATUS WALKER)AND ITS APPLICATION IN PRACTICE
Li Tian-sheng Forest Research Institute,Chinese Academy of ForestryChai Xi-min Forest Research Institute of Zhejiang ProvinceWu Zheng-Dong Chang Le Forest Farm of Zhejiang Province
Spatial distribution patterns for egg-masses,small larvae,large larvae and cocoons of the pine caterpillar were measured by means of several in- dexes of aggregation in Zhe Jiang Province.Frequency distribution of egg- masses fits to Poisson distribution quite well,and that of the small larvae, large larvae and cocoons obeys aggregation distribution,but the aggregation indexes are highest in small larvae and lowest in cocoons. Iwao's method of regression of mean crowding()on mean density() is a good method for detecting the aggregation patterns.In the pine caterpillar, small larvae,large larvae and cocoons,all relation in a series of distri- bution is fitted to a single linear regression for α0,β1.Iwao's equations for data transformation were applied and tested for its fitness,the transformed data all obey normal distribution and the tests of heterogeneity of variance and non-additivity indicate that the results of transformation are well fitted. From this method the optimal sampling size is determined,the sequential analysis is also applied. In the pine caterpillar,the basic component of the distribution (i.e.large larvae) is a loose colony.The size of the colony and the distribution of indivi- duals in colony remain to be studied.
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