Entomopathogenic nematodes (EPNs) belonging to the Heterorhabditis spp. harbour symbiotically associated bacteria which are toxic to a wide range of insect pests. Isolation, purification, characterization and mass multiplication of such bacteria will be a promising strategy in the management of the pests. This study was carried out to isolate the EPN from different locations, isolate and purify the bacterial colonies, characterize the bacteria through morphological and molecular strategies and to test the efficacy of different bacteria in the control of polyphagous Tetranychus truncatus Ehara mites. EPNs were isolated from soil samples at 11 localities of Kerala State, India, and used to infect the Galleria mellonella L. larvae. Bacteria associated with the haemolymph of the infected larvae were isolated, which on NBTA medium have produced circular to irregular, entire, opaque and smooth colonies. Sequence characterization of the 16S rRNA revealed nine isolates namely: one symbiotic bacterium Photorhabdus luminescens, two Pseudomonas aeruginosa, five Ochrobactrum sp. and one Stenotrophomonas maltophilia. Phylogenetic analysis using the sequences has further confirmed the bacterial identity. Evaluation of the cell suspension (CS) and cell-free supernatant (CFS) of P. luminescens, P. aeruginosa and Ochrobactrum sp. for their adulticidal and ovicidal efficiencies on T. truncatus had identified significant adulticidal effects by P. luminescens, followed by P. aeruginosa. After 96 h of treatment, P. luminescens at 108 cells/ml resulted in a significantly higher mortality rate of adult mites (64.00 and 60.67%, respectively, for CFS and CS), compared to that resulted by P. aeruginosa (38.67 and 33.33%). Results of this study showed that P. luminescens associated with the EPN Heterorhabditis spp. is a promising biocontrol agent for T. truncatus.

中文翻译：

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与昆虫病原线虫 Heterorhabditis spp 相关的细菌的分离和评估。对抗蜘蛛螨，Tetranychus truncatus Ehara (Acari: Tetranychidae)

属于 Heterorhabditis spp 的昆虫病原线虫 (EPN)。含有对多种害虫有毒的共生细菌。这种细菌的分离、纯化、表征和大量繁殖将是一种有前途的害虫管理策略。本研究旨在从不同位置分离EPN，分离和纯化细菌菌落，通过形态学和分子策略表征细菌，并测试不同细菌在控制多食叶螨叶原螨中的功效。EPNs 从印度喀拉拉邦 11 个地区的土壤样本中分离出来，用于感染 Galleria mellonella L. 幼虫。分离出与受感染幼虫的血淋巴相关的细菌，在 NBTA 培养基上产生圆形至不规则、完整、不透明和光滑的菌落。16S rRNA 的序列表征揭示了九个分离株，即：一种共生细菌发光光杆菌，两种铜绿假单胞菌，五种 Ochrobactrum sp。和一种嗜麦芽窄食单胞菌。使用这些序列的系统发育分析进一步证实了细菌的身份。发光假单胞菌、铜绿假单胞菌和 Ochrobactrum sp. 的细胞悬液 (CS) 和无细胞上清液 (CFS) 的评估。由于它们对 T. truncatus 的杀成虫和杀卵效率已确定 P. luminescens 具有显着的杀成虫效果，其次是 P. aeruginosa 。处理 96 小时后，108 个细胞/ml 的 P. luminescens 导致成年螨虫的死亡率显着升高（CFS 和 CS 分别为 64.00 和 60.67%），与铜绿假单胞菌（38.67 和 33.33%）的结果相比。这项研究的结果表明 P. luminescens 与 EPN Heterorhabditis spp 相关。是一种很有前途的 T. truncatus 生物防治剂。