ABSTRACT

Ten Steinernema abbasi isolates were obtained during a soil survey in Western Uttar Pradesh, India. The nematode isolates were characterised using morpho-taxometrical and molecular approaches, and their biopesticide properties against two lepidopteran pests (i.e. Helicoverpa armigera and Spodoptera litura) were assessed. In addition, their Xenorhabdus bacterial symbionts were isolated, and physiologically and molecularly characterised. Lastly, the geographical dissemination of Steinernema abbasi was studied using meta-analyses of their ITS rDNA NCBI GenBank records. The morphology of the nematode isolates of this study was comparable with the S. abbasi specimens used in the original description with the only discrepancy that well-developed mucrons were observed in the second generation males and females of this study. The analyses of ITS rDNA from NCBI records show that S. abbasi is ubiquitous throughout the Indian subcontinent but rarely reported from South East Asia. There are no reports of this species outside of Asia. The bacterial symbionts of S. abbasi isolates show the phenotypic and molecular similitude with Xenorhabdus indica. Bioassays showed that the nematode isolates were highly virulent against cotton bollworm (Helicoverpa armigera) and tobacco cutworm (Spodoptera litura) larvae. This species being native to Indian Subcontinent could be explored further as a biocontrol agent.

摘要

在印度北方邦西部的土壤调查期间获得了10株Steinernema abbasi分离株。使用形态分类学和分子方法对线虫分离株进行了表征，并评估了它们对两种鳞翅目害虫（即棉铃虫和斜纹夜蛾）的生物杀虫剂特性。此外，它们的致病杆菌共生体被分离出来，并在生理和分子上进行了表征。最后，使用 ITS rDNA NCBI GenBank 记录的元分析研究了Steinernema abbasi的地理传播。本研究的线虫分离株的形态与S. abbasi与原始描述中使用的标本的唯一差异是在本研究的第二代雄性和雌性中观察到发育良好的 mucron。来自 NCBI 记录的 ITS rDNA 分析表明，S. abbasi在整个印度次大陆无处不在，但很少在东南亚报道。在亚洲以外没有关于该物种的报道。S. abbasi分离株的细菌共生体显示出与Xenorhabdus indica的表型和分子相似性。生物测定表明，线虫分离株对棉铃虫（Helicoverpa armigera）和烟草地老虎（Spodoptera litura ）具有高毒力) 幼虫。这种原产于印度次大陆的物种可以作为生物防治剂进一步探索。