Vitta Apichat, Fukruksa Chamaiporn, Yimthin Thatcha, Deelue Kitsakorn, Sarai Chutima, Polseela Raxsina, Thanwisai Aunchalee
Southeast Asian J Trop Med Public Health. 2017 Jan;48(1):18-26.
Entomopathogenic nematodes (EPNs) of the genera Steinernema and Heterorhabditis are used as biocontrol agents for insect pests. Survey of indigenous EPNs provides not only the diversity aspects but also the contribution in pest management in local areas. The objective of this study was to survey EPNs in upper northern Thailand. Nine hundred seventy soil samples were obtained from 194 sites in upper northern region of Thailand; of these 60 (6.2%) had EPNs in 2 genera: Steinernema (32 isolates) and Heterorhabditis (28 isolates). Most EPNs were isolated from loam with a soil temperature of 24-38°C, a pH of 1.5-7.0 and a soil moisture content of 0.5-6.8%. Molecular identification based on sequencing of a partial region of an internal transcribed spacer was performed for Heterorhabditis and the 28S rDNA for Steinernema. A BLASTN search of known sequence EPNs revealed 24 isolates of S. websteri and one isolate of S. scarabaei were identified; closely related to S. websteri (accession no. JF503100) and S. scarabaei (accession no. AY172023). The Heterorhabditis species identified were: H. indica (11 isolates), H. gerrardi (2 isolates) and Heterorhabditis sp (8 isolates). Phylogenetic analysis revealed 11 isolates of Heterorhabditis were related to H. indica; 2 isolates were related to Heterorhabditis gerrardi and 8 isolates were closely related to Heterorhabditis sp SGmg3. The study results show the genetic diversity of EPNs and describe a new observation of S. scarabaei and H. gerrardi in Thailand. This finding is new and provides important information for further study on using native EPNs in biological control.
斯氏线虫属（Steinernema）和异小杆线虫属（Heterorhabditis）的昆虫病原线虫被用作害虫的生物防治剂。对本地昆虫病原线虫的调查不仅能提供其多样性方面的信息，还能了解它们在当地害虫管理中的作用。本研究的目的是调查泰国北部上游地区的昆虫病原线虫。从泰国北部上游地区的194个地点采集了970份土壤样本；其中60份（6.2%）含有两个属的昆虫病原线虫：斯氏线虫属（32个分离株）和异小杆线虫属（28个分离株）。大多数昆虫病原线虫分离自壤土，土壤温度为24 - 38°C，pH值为1.5 - 7.0，土壤湿度为0.5 - 6.8%。对异小杆线虫进行了基于内部转录间隔区部分区域测序的分子鉴定，对斯氏线虫进行了28S rDNA测序。对已知序列的昆虫病原线虫进行BLASTN搜索，鉴定出24个韦氏斯氏线虫分离株和1个金龟子斯氏线虫分离株；它们与韦氏斯氏线虫（登录号JF503100）和金龟子斯氏线虫（登录号AY172023）密切相关。鉴定出的异小杆线虫种类有：印度异小杆线虫（11个分离株）、杰氏异小杆线虫（2个分离株）和异小杆线虫属sp（8个分离株）。系统发育分析表明，11个异小杆线虫分离株与印度异小杆线虫相关；2个分离株与杰氏异小杆线虫相关，8个分离株与异小杆线虫属sp SGmg3密切相关。研究结果显示了昆虫病原线虫的遗传多样性，并描述了泰国金龟子斯氏线虫和杰氏异小杆线虫的新观察结果。这一发现是新的，为进一步研究利用本地昆虫病原线虫进行生物防治提供了重要信息。
