斜纹夜蛾种群空间动态

利用频次分布法和分布型指数研究了斜纹夜蛾低中龄幼虫在菜芯Ｂｒａｓｓｉｃａ ｐａｒａｃｈｉｎｅｎｓｉｓ Ｂａｉｌｅｙ地内和种群空间分布图式，并研究了各龄幼虫在菜株上的垂直分布。结果表明：斜纹夜蛾 龄幼虫在菜株上呈聚集颁上，频次分布拟事的结果大部分样本符合负二项分布，半产本符合奈曼分布，而不符合泊松分布，频次分布拟事的结果大部样本符合负二项分布，半数样本符合奈曼分布，而不符合泊松分布，幼虫在菜株上的分

Spatial Dynamics of Common Cutworm,Spodopter litura Fab.Population on Brassica parachinensis B.

The frequency distribiution fit to the patterns of distribution and the dispersion indices were used to describe the spatial patterns of the common cutworm;Spodoptera litura Fab. and the vertical distribution of its larvae of all ages on vegetable plants were also studied in this paper.The results showed that most of samples of young and mid aged larvae dispersed collectively on the heart of vegetable;the results of frequency distribution assimilation agreed with Negative binomial or Neyman distribution expectation,while little agreed with expectation of the Poisson.The vertical distribution of the larvae on the plants varied with development stages of larvae.Most younger larvae lived on the upside of plants,while the 5th and 6th instar larvae hid themselves in soil,on the ground and under the droppings from plants in daytime.This meant that with the development of larvae,their dispersion lowered close to the ground. When larvae were infected with nuclear polyhedrosis virus,the dispersion of larvae moved to the up part of vegetable gradually.