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在斜纹夜蛾发生盛期,应用Iwao和Taylor两种回归方法及采用扩散系数C、平均拥挤度M’、聚集指数I、负二项分布K值、扩散指数CA值、聚块性指标M’/x、负二项分布指数L’、负二项分布扩散型指标L’/(1+x)和扩散指标Iδ等9个聚集度指标,对斜纹夜蛾幼虫在棉田的空间格局进行研究。结果表明:斜纹夜蛾幼虫在棉田内呈聚集分布。在空间格局的基础上提出了理论最适抽样数N=(t2/D2)(1/x+2.8042)和复合序贯抽样方案,提高了田间调查效率。
In the peak stage of the occurrence of Spodoptera litura, Iwao and Taylor regression methods and the use of diffusion coefficient C, average crowding degree M ’, aggregation index I, negative binomial distribution K value, diffusion index CA value, bulk index M’ / x, negative binomial distribution index L ’, negative binomial distribution diffusivity index L’ / (1 + x) and diffusion index Iδ were used to study the spatial pattern of Spodoptera litura larvae in cotton field. The results showed that Spodoptera litura larvae accumulated in the cotton field. Based on the spatial pattern, the theoretical optimum sampling number N = (t2 / D2) (1 / x + 2.8042) and compound sequential sampling scheme are proposed to improve the field survey efficiency.