烤烟留种田棉铃虫幼虫分布型与抽样技术研究

Studies on the Larval Spatial Pattern of Distribution and Sequential Sampling Technique for Cotton Bollworm in Seed Plots of Flue-cured Tobacco

棉铃虫是陕西省烤烟留种田后期主要害虫之一。幼虫分布型调查表明，它主要为波松和负二项分布，且随密度而变化，但适合于Ｔａｙｌｏｒ幂法则：Ｓ~２＝１．０７５２３ｍ^（０．９９３１）。经推导演算，得出理论抽样公式为：ｎ＝１．０７５２３（ｔ／Ｄ）~２·ｍ^（－１．００６９）适合烟田棉铃虫幼虫调查的序贯抽样模型为最多只需抽取１６株。对各种机械抽样方法比较后，认为实践中用平行线１０点１００株取样比较合适。

The cotton bollworm, Helicoverpa armigera (HUbner), is a serious pest in the seed plots of flue-cured tobacco in Bac n, Shaanxi province. It damages the flower and capsule,and cause yield loss. The investigation in the early September 1993 shows that the larval spatial patterns of distribution fits both poisson and Negative Binomial, and changes with its mean density. But they all conform to Taylor's power law,S2 = 1. 07523m0. 9931If the economic threshold (m0) is given as 0. 15 larva per plant, the Iwao's sequential sampling technique would be with the maximum sampling size of 16 plants. Having compared the different fixed-sample-size techniques, we conclude that the parallel lines technique is among the best.