Cucumber (Cucumis sativus) cultivation in commercial greenhouses occupies an important section of vegetable production in Iran. Root-knot nematode Meloidogyne javanica considered the most destructive soil-borne pathogen in cucumber growing greenhouses. In this study, biocontrol activity of three species of entomopathogenic nematodes (EPNs, i.e., Steinernema carpocapsae, S. feltiae and Heterorhabditis bacteriophora) was determined on M. javanica infecting cucumber under growth chamber and greenhouse conditions. The aqueous suspension of infective juveniles (IJs) was used in five different inoculation times (i.e., 1 or 2 weeks pre-inoculation, simultaneously, and 1 or 2 weeks post-inoculation of the pathogenic nematode into the cucumber soil). Results showed that S. carpocapsae and H. bacteriophora were capable of decreasing all the pathogenicity indices (number of galls, eggs and egg masses) of M. javanica in growth chamber, as well as greenhouse conditions. The best application time for EPNs was determined as 1 week after post-inoculation of M. javanica into the soil. Although EPNs showed significant inhibition in 25 IJ/cm² (3.8 IJ/cm³) of soil, the best biocontrol activity was observed in 125 IJ/cm² (19.1 IJ/cm³). Furthermore, the highest reduction in pathogenicity indices was observed when EPNs-colonized cadavers were used as carrier of biocontrol agents. Significant increase in plant growth indices (e.g., fresh/dry weight of shoots/roots) was recorded for all treatments except S. feltiae. Altogether, our results provide a novel insight into the applicability of EPNs against the root-knot nematode M. javanica on cucumber. Further investigations are warranted to evaluate the commercial usability of the agents in cucumber growing greenhouses in Iran.

在商业温室中种植黄瓜（Cucumis sativus）在伊朗蔬菜生产中占有重要地位。根结线虫爪哇根结线虫认为在黄瓜大棚增长最具破坏性的土传病原菌。在这项研究中，三个物种线虫（的EPN，即，生物防治活性斯carpocapsae，S.氏线虫和异小嗜菌）中的溶液来确定爪哇根结线虫在生长室和温室条件下感染黄瓜。感染性幼虫（IJs）的水悬液用于五个不同的接种时间（即，在将病原线虫接种到黄瓜土壤中之前，同时，以及在接种后1或2周后）。结果表明，腕果链霉菌和嗜细菌链球菌能够降低生长室和温室条件下爪哇沙棘的所有致病指数（胆，卵和卵重）。对EPNs的最佳施用时间被确定为爪哇茉莉花接种到土壤中后1周。尽管EPNs在25 IJ / cm ²（3.8 IJ / cm³）在土壤中，以125 IJ / cm ²（19.1 IJ / cm ³）观察到最佳的生物防治活性。此外，当将EPNs殖民化的尸体用作生物防治剂的载体时，可观察到最高的致病指数降低。对于所有处理，除链霉菌外，均记录到植物生长指数的显着增加（例如，茎/根的鲜/干重）。总之，我们的结果为EPNs对黄瓜根结线虫爪哇线虫的适用性提供了新颖的见解。有必要进行进一步的研究，以评估该制剂在伊朗黄瓜温室中的商业可用性。