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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。
According to the calculation formula of the theoretical sampling number proposed by Iwao, the larvae of cabbage budworm larvae were collected at different densities The number of samples is: n = 40.9611-2.2401. After analysis, four kinds of sampling methods to “checkerboard” sampling more samples, and the layout is uniform, sampling error is small.