Entomopathogenic nematodes (EPNs) have a great potential as a biocontrol agent for a wide range of insect pests. EPNs have attracted much interest around the world to study their distribution, virulence, and usage in the IPM programs. This research was conducted to identify the steinernematids M.22 and M.313, which were isolated during the survey of EPNs in different agricultural and ecological systems, in the Syrian coastal region between 2017 and 2020. Additionally, to evaluate the virulence of these isolates against the last instar larvae of the greater wax moth, Galleria mellonella (Linnaeus 1758) (Lepidoptera: Pyralidae), three bioassays were carried out at 18 °C. The exposure time assay was performed by applying different times (15, 30, 45, and 60 min) using a specified concentration (400 IJs/Larva). The concentration–response and one-on-one assays were conducted by using different concentrations of the infective juveniles (IJs) (5, 15, 25, and 40 IJs/L) and an individual juvenile, respectively, for 72 h of exposure. LC50 and LT50 values were calculated. The steinernematids M.22 and M.313 were isolated from 2 of 821 soil samples (0.24%). The positive isolates were identified as Steinernema affine (Bovien, 1937), based on morphological, morphometric, and molecular characterization. Steinernema affine was recovered in the walnut orchard and grassland in AL-Kadmous area of Tartus governorate, Syria. The soil type was silty loamy and silty, PH was slightly acidic, and organic matter content was 6 and 4.1%. In the exposure time assay, the mortality ratio increased gradually by increasing time, M.22 and M.313 achieved the highest mortality ratios at 60 min, which were 90.16 and 91.49%, respectively. In the concentration–response assay, complete mortality was achieved at the concentration of 40 IJs/L for both isolates. Low mortality ratios were observed in the assay of one-on-one, 20 and 23.6%, respectively. The LC50 and LT50 values were calculated and resulted in (11.7 IJs/L, 33.47 min) and (11.5 IJs/L, 32.43 min), respectively. Nonsignificant difference between both isolates was recorded. The results showed that the isolates were identical and identified as Steinernema affine. This is the first report of S. affine in Syria. It could be an effective biological control agent.

中文翻译：

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叙利亚首次报道昆虫病原线虫 Steinernema affine (Nematoda: Steinernematidae) 及其对 Galleria mellonella L. (Lepidoptera: Pyralidae) 的毒力

昆虫病原线虫 (EPNs) 具有作为多种害虫的生物防治剂的巨大潜力。EPN 引起了全世界的极大兴趣，以研究它们在 IPM 程序中的分布、毒力和使用。本研究旨在鉴定 2017 年至 2020 年间在叙利亚沿海地区的不同农业和生态系统中的 EPN 调查期间分离出的 steinernematids M.22 和 M.313。此外，评估这些分离物的毒力针对大蜡蛾的最后一龄幼虫，Galleria mellonella (Linnaeus 1758) (Lepidoptera: Pyralidae)，在 18 °C 下进行了 3 次生物测定。通过使用指定浓度 (400 IJs/Larva) 应用不同的时间 (15、30、45 和 60 分钟) 来进行暴露时间测定。通过使用不同浓度的感染性幼体 (IJs)（5、15、25 和 40 IJs/L）和个体幼体，分别暴露 72 小时，进行浓度-反应和一对一测定。计算 LC50 和 LT50 值。从 821 个土壤样品中的 2 个 (0.24%) 中分离出 steinernematids M.22 和 M.313。根据形态学、形态学和分子特征，阳性分离株被鉴定为 Steinernema affine (Bovien, 1937)。Steinernema affine 在叙利亚塔尔图斯省 AL-Kadmous 地区的核桃园和草地中发现。土壤类型为粉质壤质粉质，PH呈微酸性，有机质含量分别为6%和4.1%。在暴露时间测定中，死亡率随着时间的增加而逐渐增加，M.22和M. 313 人在 60 分钟时的死亡率最高，分别为 90.16% 和 91.49%。在浓度反应分析中，两种分离株在浓度为 40 IJs/L 时实现了完全死亡。在一对一分析中观察到低死亡率，分别为 20% 和 23.6%。计算了 LC50 和 LT50 值，结果分别为 (11.7 IJs/L, 33.47 min) 和 (11.5 IJs/L, 32.43 min)。记录了两种分离株之间的非显着差异。结果表明，分离株是相同的，并被鉴定为 Steinernema affine。这是S. affine在叙利亚的首次报道。它可能是一种有效的生物控制剂。在一对一分析中观察到低死亡率，分别为 20% 和 23.6%。计算了 LC50 和 LT50 值，结果分别为 (11.7 IJs/L, 33.47 min) 和 (11.5 IJs/L, 32.43 min)。记录了两种分离株之间的非显着差异。结果表明，分离株是相同的，并被鉴定为 Steinernema affine。这是S. affine在叙利亚的首次报道。它可能是一种有效的生物控制剂。在一对一分析中观察到低死亡率，分别为 20% 和 23.6%。计算了 LC50 和 LT50 值，结果分别为 (11.7 IJs/L, 33.47 min) 和 (11.5 IJs/L, 32.43 min)。记录了两种分离株之间的非显着差异。结果表明，分离株是相同的，并被鉴定为 Steinernema affine。这是S. affine在叙利亚的首次报道。它可能是一种有效的生物控制剂。在叙利亚仿射。它可能是一种有效的生物控制剂。在叙利亚仿射。它可能是一种有效的生物控制剂。