Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok, 65000, Thailand.
Department of Agriculture Science, Faculty of Agriculture Natural Resources and Environment, Naresuan University, Phitsanulok, 65000, Thailand.
J Helminthol. 2020 Sep 14;94:e192. doi: 10.1017/S0022149X20000735.
Entomopathogenic nematodes (EPNs) Steinernema and Heterorhabditis and their symbiotic bacteria, Xenorhabdus and Photorhabdus, have been successfully used for the control of insect pests. The objectives of this study were to survey the EPNs and symbiotic bacteria in the agricultural areas of the Phitsanulok province, Thailand, and to study the association between the soil parameters and presence of EPNs. We collected 200 soil samples from 40 soil sites in agricultural areas (field crops, horticulture crops and forest). The prevalence of EPNs was 8.0% (16/200). Fifteen of the EPN isolates were molecularly identified (based on 28S ribosomal DNA and internal transcribed spacer regions) as Steinernema siamkayai. Seven isolates of Xenorhabdus stockiae were identified using recombinase A sequencing. Phylogenetic analysis revealed that all the Steinernema and Xenorhabdus isolates were closely related to S. siamkayai (Indian strain) and X. stockiae (Thai strain), respectively. Significantly more EPNs were recovered from loam than from clay. Although the association between soil parameters (pH, temperature and moisture) and the presence of EPNs was not statistically significant, the elevation levels of the soil sites with and without EPNs were found to be different. Moreover, statistical comparisons between the agricultural areas revealed no significant differences. Therefore, we concluded that S. siamkayai is associated with X. stockiae in agricultural areas and that there is no association between the soil parameters of agricultural areas and presence of EPNs, except for soil texture and the elevation. Steinernema siamkayai may be applied as a biocontrol agent in agricultural areas.
昆虫病原线虫（EPNs）斯氏线虫属和异小杆线虫属及其共生细菌，黄杆菌属和 Photorhabdus 属，已成功用于防治害虫。本研究的目的是调查泰国碧差汶府农业区的 EPNs 和共生细菌，并研究土壤参数与 EPNs 存在之间的关系。我们从农业区（大田作物、园艺作物和森林）的 40 个土壤地点采集了 200 个土壤样本。EPNs 的流行率为 8.0%（16/200）。15 个 EPN 分离株通过基于 28S 核糖体 DNA 和内部转录间隔区的分子鉴定被鉴定为斯氏线虫 siamkayai。使用重组酶 A 测序鉴定了 7 个 Xenorhabdus stockiae 分离株。系统发育分析表明，所有的斯氏线虫和黄杆菌分离株与 siamkayai（印度株）和 X. stockiae（泰国株）分别密切相关。从壤土中回收的 EPNs 明显多于从粘土地中回收的。尽管土壤参数（pH 值、温度和湿度）与 EPNs 存在之间的关联没有统计学意义，但发现有和没有 EPNs 的土壤地点的海拔水平不同。此外，对农业区进行的统计比较没有发现显著差异。因此，我们得出结论，在农业区，S. siamkayai 与 X. stockiae 相关，除了土壤质地和海拔外，农业区的土壤参数与 EPNs 的存在之间没有关联。S. siamkayai 可能作为一种生物防治剂应用于农业区。
