玉米叶螨空间格局及其二阶抽样技术研究

Study on the Space Pattern and Subsampling Technique of Corn Leaf Mites

玉米田叶螨空间格局，在较低螨口密度时呈聚集分布，在较高密度时呈均匀分布。玉米植株叶层之间，分布叶螨数量差异显著，在不同田块之间，差异不显著，玉米发育到１５～１６叶片时，第１～１０叶层上分布叶螨量占总螨量的９５．１％．应用Ｉｗａｏ根据Ｍ＊－ｍ关系提出的两阶抽样模型估计，在给定Ｄ＝０．１０，０．１５，０．２０精确水平时，每株查第１～１０叶层螨量，需要抽查的玉米株数的平均值分别为７７，３４，１９株。当取９５％置信度时，区间估计下层：Ｐ下＝〔０．９２７８，０．９７１８〕，Ｐ下＝０．９４９８，上层：Ｐ上＝〔０．０２８２，０．０７２２〕，Ｐ上＝０．０５０２．

The research results show that the space pattern of corn leaf mites has a gathering distribution form in lower density of mites while a uniform distribution in higher one.The difference of the leaf mite quantities among corn stem leaf layers is obvious while among various fields it is unobvious.When corn grows to its 15-16 leaves the quantity on the first 10 leaves accounts for 95.1% of the total amount.According to the subsample model appraisal with application of Iwao and M * m under the condition of D =0.10, 0.15 and 0.20 exact level,the averages for the sampling are 77,34 and 19,if we have an assessment of the quantity of mites on every stem from the first leaf to the tenth.While we take 95% degree of confidence,the estimation of smaller interval is P d own (0.9278-0.9718) and d own=0.9498,and the larger interval is P up (0.0282-0.0722 and up =0.0502.