Alatawi F J, Opit G P, Margolies D C, Nechols J R
Kansas State University, Department of Entomology, 123 West Waters Hall, Manhattan, Kansas 66506-4004, USA.
J Econ Entomol. 2005 Jun;98(3):1040-7. doi: 10.1603/0022-0493-98.3.1040.
The twospotted spider mite, Tetranychus urticae Koch, is an important pest of impatiens, a floricultural crop of increasing economic importance in the United States. The large amount of foliage on individual impatiens plants, the small size of mites, and their ability to quickly build high populations make a reliable sampling method essential when developing a pest management program. In our study, we were particularly interested in using spider mite counts as a basis for releasing biological control agents. The within-plant distribution of mites was established in greenhouse experiments and these data were used to identify the sampling unit. Leaves were divided into three zones according to location on the plant: inner, intermediate, and other. On average, 40, 33, and 27% of the leaves belonged to the inner, intermediate, and other leaf zones, respectively. However, because 60% of the mites consistently were found on the intermediate leaves, intermediate leaves were chosen as the sampling unit. These results lead to the development of a presence-absence sampling method for T. urticae by using Taylor coefficients generic for this pest. The accuracy of this method was verified against an independent data set. By determining numerical or binomial sample sizes for consistently estimating twospotted spider mite populations, growers will now be able to determine the number of predatory mites that should be released to control twospotted spider mites on impatiens.
二斑叶螨（Tetranychus urticae Koch）是凤仙花的一种重要害虫，凤仙花是美国一种经济重要性不断增加的花卉作物。单株凤仙花植株上叶片数量众多、螨类体型微小以及它们能够迅速建立起高密度种群，这使得在制定害虫管理计划时，可靠的抽样方法至关重要。在我们的研究中，我们特别关注以叶螨数量为基础来释放生物防治剂。通过温室实验确定了螨类在植株内的分布情况，这些数据被用于确定抽样单位。根据叶片在植株上的位置，将叶片分为三个区域：内部、中间和其他。平均而言，分别有40%、33%和27%的叶片属于内部、中间和其他叶区。然而，由于60%的螨类始终在中间叶片上被发现，因此选择中间叶片作为抽样单位。这些结果促使利用针对这种害虫的通用泰勒系数开发了一种二斑叶螨的有无抽样方法。该方法的准确性通过一个独立数据集进行了验证。通过确定用于持续估计二斑叶螨种群数量的数值或二项式样本大小，种植者现在将能够确定为控制凤仙花上的二斑叶螨而应释放的捕食螨数量。
