A survey of entomopathogenic nematodes and their symbiotic bacteria in agricultural areas of northern Thailand

Abstract

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.

Evaluation of indigenous entomopathogenic nematodes in Southwest China as potential biocontrol agents against Spodoptera litura (Lepidoptera: Noctuidae)

“…can occur in the acid soil ( Campos-Herrera et al, 2019 ). In general, the soil clay content was inversely related to the presence of EPNs ( Ardpairin et al, 2020 ; Mracek et al, 2005 ). Likewise, the isolated of Heterorhabditis or Steinernema were found in the soil with the soil clay content lower than 50 in our study.…”

Evaluation of Native Entomopathogenic Nematode Isolates for the Management of Selected Insect Pests in Nigeria

“…Entomopathogenic nematodes possess a unique combination of attributes that make them a promising alternative to synthetic chemical insecticides for pest control (Divya and Sankar, 2009;Abd-Elgawad, 2019). These nematodes have exceptional potential for biological control of insects as conferred by the symbiotic complex formed with bacteria of the genus Xenorhabdus associated with the Steinernema species and Photorhabdus with the Heterorhabditis species (Grewal et al, 2001;Kaya et al, 20006;Ardpairin et al, 2020) to achieve their successful parasitism and quick-kill effect on their insect host. This ability was evidenced in the high mortality observed on the test insects.…”

Entomopathogenic Nematodes and Their Symbiotic Bacteria from the National Parks of Thailand and Larvicidal Property of Symbiotic Bacteria against Aedes aegypti and Culex quinquefasciatus

“…This was followed by the identification of numerous species found in one study included S. websteri , S. khoisanae , H. indica , H. bacteri-ophora and H. baujardi [ 15 ], and subsequently, S. websteri reported from lower northern Thailand [ 16 , 17 ]. At present, 15 EPN species representing a variety of ecological soil types in different geographic regions of Thailand have been reported including, S. siamkayai , S. surkhetense , S. websteri (synonym S. carpocapsae ), S. scarabiae , S. kushidai , S. minutum , S. khoisanae , S. longicaudum , S. guangdongense , S. huense , S. sangi , H. indica (synonym H. gerrardi ), H. baujardi (synonym H. somsookae ), H. bacteiophora and H. zealandica [ 15 , 17 , 18 , 19 , 20 , 28 , 35 , 36 , 38 , 39 , 40 , 41 ]. In addition, three Steinernema isolates ( Steinernema sp.…”