The tobacco cutworm, Spodoptera litura [Fab.] (Lepidoptera: Noctuidae), is a devastating insect pest of several crops. Entomopathogenic nematodes (EPNs) of the families Heterorhabditidae and Steinernematidae are used as an alternative control measure in lieu of the hazardous synthetic chemical applications. A survey of naturally occurring EPNs was conducted across the province of Cotabato, Philippines, covering a total of 5 municipalities with 25 villages. Galleria-baiting technique was employed to recover nematodes from peanut and grassland soils. Out of 50 soil samples collected, only 5 samples harbored nematodes, indicating a recovery of 10%. Preliminary morphological data identified only one EPN under the genera Heterorhabditis (1 isolate), whereas 4 were facultative necromenic nematodes from the genera Metarhabditis (2 isolates) and Oscheius (2 isolates). Analysis of D2D3 segments of the 28S rDNA confirmed high sequence similarity to Heterorhabditis indica, Metarhabditis rainai, Oscheius insectivora, and Oscheius sp. This is the first record of H. indica and M. rainai in the entire region, whereas the first record for Oscheius spp. in the Philippines. Furthermore, the biocontrol potential of the local H. indica infective juvenile (IJ) populations (PIGCD1) isolated from peanut was assessed against the tobacco cutworm, S. litura, under laboratory conditions. The mean percentage mortality caused by H. indica on S. litura at 7 different concentrations ranged from 0-100% at 24 h post inoculation. The lethal concentration (LC50) required to kill 50% of the S. litura larvae population with H. indica was 7.13±1 (IJs/larva). The use of Galleria-baiting method is a convenient approach to detect EPNs including other facultative necromenic nematodes from the soils. Obtained data indicated that the local H. indica isolate can be a promising alternative measure to suppress the economically important insect pest, S. litura, and this may provide significant outlook to establish the biocontrol program in the country.

中文翻译：

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调查和鉴定菲律宾哥打巴托省的昆虫致病性线虫，以针对烟草鳞茎斜纹夜蛾（Fabodius）（鳞翅目：夜蛾科）进行生物防治。

烟草鳞虫（Spodoptera litura [Fab。]（鳞翅目：夜蛾科））是几种农作物的毁灭性害虫。Heterorhabditidae和Steinernematidae家族的致病性线虫（EPN）被用作替代控制措施，代替了危险的合成化学应用。在菲律宾哥打巴托省对自然产生的EPNs进行了调查，涵盖了5个城市的25个村庄。采用圆顶诱饵技术从花生和草地土壤中回收线虫。在收集的50个土壤样品中，只有5个样品带有线虫，表明其恢复率为10％。初步的形态学数据仅鉴定出一种异位性关节炎（一种分离株）下的EPN，而4个是来自Metrahabditis属（2个分离株）和Oscheius（2个分离株）的兼性坏死线虫。分析28S rDNA的D2D3片段，证实与印度洋杂种人，Rainhahabditis Rainai，Oscheius insectivora和Oscheius sp具有高度的序列相似性。这是H. indica和M. rainai在整个地区的第一笔记录，而Oscheius spp的第一笔记录。在菲律宾。此外，在实验室条件下，评估了从花生中分离出来的当地H. indica Indica感染性少年（IJ）种群（PIGCD1）对烟草鳞茎S. litura的生防潜力。接种后24小时，在7种不同浓度下，lit麻链球菌对印度caused链球菌造成的平均死亡率百分数为0-100％。杀死50％的S所需的致死浓度（LC50）。带有H稻的虫幼虫种群为7.13±1（IJs /幼虫）。使用Galleria诱饵方法是从土壤中检测EPN的便捷方法，其中包括其他兼性的线虫性线虫。获得的数据表明，当地的H. indica分离株可以作为抑制经济上重要的害虫S. litura的一种有前途的替代措施，这可能为在该国建立生物防治计划提供重要的前景。