Biologische Bekämpfung des Kalifornischen Blütenthrips Frankliniella occidentalis unter besonderer Berücksichtigung des Einsatzes von entomopathogenen Nematoden

西花蓟马（Frankliniella occidentalis (Pergande)）（蓟翅目：蓟科）是欧洲温室的主要害虫之一，危害多种重要的经济作物，如蔬菜和观赏植物。由于其摄食行为和生活策略的隐蔽性，使其难以控制。昆虫病原线虫（EPNs）（横纹肌目：斯坦虫科和异虫虫科）已被发现对土栖WFT发育阶段具有毒力。但是，控制害虫的EPNs质量的因素是不同的。在目前的研究中，对EPN高毒力菌株进行更广泛的筛选，并将详细研究EPN功效的非生物和生物限制。这些包括寄主植物的生长介质类型的影响，生长介质的水分含量，温度，以及冲洗线虫到WFT化蛹深度所需的灌溉水量。此外，本研究还探讨了灌浆剂的密度和化蛹深度、灌浆时间和灌浆频率对灌浆剂高峰种群水平的影响，以及灌浆剂在半野外条件下的持久性。此外，还将研究EPNs与其他生物防治剂联合使用的可能性，如以生活在树叶上的WFT为食的掠食性螨（Amblyseius spp.）和以生活在土壤上的WFT为食的掠食性螨（Hypoaspis aculeifer）。

Western Flower Thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is one of the key pests in European greenhouses attacking a wide range of economically important crops such als vegetables and ornamentals. Due to its cryptic feeding behaviour and life strategy control of WFT is difficult. Entomopathogenic nematodes (EPNs) (Rhabditida: Steinernmatidae and Heterorhabditidae) are alredy found to be virulent aginst soil-dwelling development stages of WFT. However, different factors determine quality of EPNs for the control of insect pests. In the present study a broader screening for high virulent strains of EPNs is envisaged and abiotic and biotic constraints for EPN efficacy will be investigated in detail. These include the effect of types of growing media of the host plants, moisture content of the growing media, temperatures, and amount of irrigation water required to wash the nematodes down to the depth of pupation of WFT will be examined. Moreover, the effects of density and depth of pupation of WFT, time and frequency of EPNs application in respect to peak population levels of WFT, and persistence of EPN under semi-field conditions will also be investigated. Furthermore, the possibility of combining EPNs with other biocontrol agents of WFT, i.e. predatory mites (Amblyseius spp.) that feed on foliage-inhabiting WFT life-stages and the predatory mite Hypoaspis aculeifer that prey on soil-dwelling developmental stages of WFT will be investigated.