Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
J Econ Entomol. 2011 Dec;104(6):1900-8. doi: 10.1603/ec11127.
Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a native pest of dry beans (Phaseolus vulgaris L.) and corn (Zea mays L.). As a result of larval feeding damage on corn ears, S. albicosta has a narrow treatment window; thus, early detection of the pest in the field is essential, and egg mass sampling has become a popular monitoring tool. Three action thresholds for field and sweet corn currently are used by crop consultants, including 4% of plants infested with egg masses on sweet corn in the silking-tasseling stage, 8% of plants infested with egg masses on field corn with approximately 95% tasseled, and 20% of plants infested with egg masses on field corn during mid-milk-stage corn. The current monitoring recommendation is to sample 20 plants at each of five locations per field (100 plants total). In an effort to develop a more cost-effective sampling plan for S. albicosta egg masses, several alternative binomial sampling plans were developed using Wald's sequential probability ratio test, and validated using Resampling for Validation of Sampling Plans (RVSP) software. The benefit-cost ratio also was calculated and used to determine the final selection of sampling plans. Based on final sampling plans selected for each action threshold, the average sample number required to reach a treat or no-treat decision ranged from 38 to 41 plants per field. This represents a significant savings in sampling cost over the current recommendation of 100 plants.
白纹稻弄蝶（Smith）（鳞翅目：夜蛾科）是一种原产于干豆（菜豆）和玉米（玉米）的害虫。由于幼虫在玉米穗上取食造成的损害，白纹稻弄蝶的处理窗口很窄；因此，在田间及早发现该害虫至关重要，卵块取样已成为一种流行的监测工具。目前，作物顾问使用三种玉米和甜玉米的田间行动阈值，包括在甜玉米抽丝期有 4%的植株被卵块侵染、在约 95%抽穗的玉米上有 8%的植株被卵块侵染和在中乳期玉米上有 20%的植株被卵块侵染。目前的监测建议是在每个田块的五个位置各取 20 株（共 100 株）。为了制定一种更具成本效益的白纹稻弄蝶卵块抽样计划，使用 Wald 的序贯概率比检验法开发了几种替代二项式抽样计划，并使用抽样计划验证的重抽样（RVSP）软件进行了验证。还计算了效益成本比，并用于确定抽样计划的最终选择。根据为每个行动阈值选择的最终抽样计划，达到处理或不处理决策所需的平均样本数从每个田块 38 到 41 株不等。与目前推荐的 100 株相比，这代表着抽样成本的显著节省。
