渭北旱塬油菜苗期蚜虫空间分布型及抽样技术的研究

The Spatial Distribution Patterns and Sequential Sampling for the Population of Rape Aphids in Seedling Stage of Rape on the Weibei Rainfed Highland

应用聚集性指标mx^(1/2),s^2x^(1/2),丛生指标I,Iwaom—x回归及Taylor幂法则等,对乾县、耀县等地油菜苗期蚜虫空间分布型的系统进行了研究,结果表明,油菜苗期蚜虫空间分布呈聚集分布状态,应用Iwaom—x回归法及Southwood公共k值法求得理论抽样模式;在此基础上建立了不同防治指标下的Iwao序贯抽样表及不同精度水平下的Green序贯抽样图;结合Iwao和Green两个抽样模型,建立了Iwao-Green复序贯抽样模型,从而在某些情况下,大大地减少了抽样数并提高了精度。

The spatial distribution pattterns of rape aphids in seedling stage of rape were stu-died by aggregation index (m/x), s^2/x, index of clumping (I), Iwao's method of regres-sion of mean crowding(m) on mean,density(x) and the Taylor's power law in Qianxian,Yaoxian counties,etc. in Shaanxi Province, The results indicated that the spatial distri-bution patterns for rape aphids in the seedling stage of rape were the aggregation distri-bution. The theoretical models of optimization sampling were obtained with the methodof Iwao's regressiong of mean crowding (m) on mean density(x) and the method ofSouthwood's Kc on the basis of which a table of Iwao's sequential sampling for variouscontrol standards and the diagrams of Green's sequential sampling for various accuracieswere worked out. One method of Iwao -- Green compound sequential sampling of rapeaphids was established with two models of Iwao and Green's sequential sampling there-by greatly reducing the number of the samples and improving the accuracies under somesituations.