甘蓝夜蛾幼虫在甜菜田的空间分布型及抽样技术

A Study on Spatial Distribution and Sampling Techniques of the Larvae of Cabbage Army Worm in the Sugarbeet Fields

用多种方法分析了甘蓝夜蛾幼虫在甜菜田的分布型为采集分布，聚集原因由昆虫本身特性所致；按Ｉｗａｏ提出的理论抽样数计算公式，得出了甘蓝夜蛾幼虫在不同密度下的抽样数为：ｎ＝４０．９６１１－２．２４０１。经分析，４种取样方法中以“棋盘试”取样样点多，且布局均匀，取样误差小。

We have got a result that spatial distribution of the larvae of Cabbage army worm（Barathra brassicae）in the sugarbeet with bome methods which can be classified into focaldistribution，due to the specific properties of the larvae. According to Iwao＇s calculating for-mula for theoretical sampling number，we get the formula for calculating the sampling num-ber of the larvae with different densities．By comparison，the sam-pling method of chessboard-type from the 5 type methods is more distribution of samplingpoints and sampling error smaller.