Department of Entomology, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel.
J Econ Entomol. 2010 Aug;103(4):1086-93. doi: 10.1603/ec09373.
Action thresholds are traditionally based on the density of pests and the economic damage they cause to crops. Pest damage assessments are usually made in a "sterile" environment, devoid of extenuating factors such as predators, parasitoids, and alternative food sources. Recently, the effects of a predator or parasitoid species have been considered. However, interactions between natural enemy species (intraguild predation and interference), which are common in agricultural fields, have not been incorporated yet into decision-making tools. We conducted a series of leaf disc and potted plant trials to evaluate the effects of two predator species, the anthocorid Orius laevigatus (Fieber) and the phytoseiid Neoseiulus cucumeris (Oudemans) on the density of and fruit damage inflicted by western flower thrips, Frankliniella occidentalis (Pergande). We then used the obtained results to develop a pest management decision-making tool for the control of western flower thrips. Because strawberries (Fragaria x ananassa Duchesne) flower in cycles, pollen, a food source for both predators and the pest, is periodically available in the system and has also been incorporated in our decision-making tool. The developed new management tool would allow the relaxation of the economic threshold (ET) for western flower thrips in strawberry flowers. The presence of an average of a single O. laevigatus per flower for example, may allow that relaxation of the ET by 40% (from 10 to 14 western flower thrips per flower) when pollen is available during the winter. Because field monitoring shows that O. laevigatus populations in Israeli strawberry often reach mean densities of three to four per flower, the new approach promises to drastically reduce the employment of toxic insecticides.
传统上，行动阈值是基于害虫密度和它们对作物造成的经济损害来确定的。害虫损害评估通常在“无菌”环境中进行，不考虑捕食者、寄生蜂和替代食物来源等减轻因素。最近，已经考虑了捕食者或寄生蜂物种的影响。然而，在农业领域中很常见的天敌物种（种内捕食和干扰）之间的相互作用尚未纳入决策工具中。我们进行了一系列叶片圆盘和盆栽植物试验，以评估两种捕食者物种，即小花蝽 Orius laevigatus (Fieber) 和智利小植绥螨 Neoseiulus cucumeris (Oudemans)，对西部花蓟马、佛罗里达西部花蓟马（Frankliniella occidentalis (Pergande）密度和果实损害的影响。然后，我们使用获得的结果开发了一种用于控制西部花蓟马的害虫管理决策工具。由于草莓（Fragaria x ananassa Duchesne）周期性开花，花粉是捕食者和害虫的食物来源，因此系统中会定期提供花粉，并已纳入我们的决策工具中。开发的新管理工具将允许放宽草莓花中西部花蓟马的经济阈值 (ET)。例如，当冬季有花粉时，每朵花平均存在一只小花蝽，就可以将 ET 放宽 40%（从每朵花 10 到 14 只西部花蓟马）。由于田间监测表明，以色列草莓中小花蝽的种群密度经常达到每朵花三到四只，因此新方法有望大大减少有毒杀虫剂的使用。
