Molecular characterisation of novel isolates of entomopathogenic nematodes

Abstract

Entomopathogenic nematodes belong to the families of Steinernematidae and Heterorhabditidae. They are obligate and lethal parasites of insects that can provide effective control of some important pests of commercial crops. A total of 53 isolates of EPN were molecularly characterised (ITS region-based) in the present study. Most of the studied isolates belong to theSteinernemagenus and only few isolates belong to theHeterorhabditisgenus. The phylogenetic relations ofSteinernemaandHeterorhabditisspecies were analysed by utilising the maximum likelihood method. In theSteinernemaphylogenetic tree, 99 isolates formed five major, moderately or highly reinforced clades: clade I:affine-intermediumgroup; clade II:carpocapsae-siamkayai-tami-scapterisci; clade III:bicornutum-riobrave-thermophilum; clade IV:glaseri-arenarium-karii-longicaudum; and clade V:feltiae-schliemanni-kushidai-kraussei-oregonense. The BLAST analysis of the ITS region of the rDNA of the steinernematid isolate PAL10 showed a rather low similarity of 93% withS. vulcanicum(accession number: GU929442), supporting the possible designation of a new species. In theHeterorhabditisphylogenetic tree, 25 isolates formed three main clades: clade I:bacteriophora-argentinensis-hepialius; clade II:baujardi-sonorensis-amazonensis; and clade III:indica-brevicaudis-hawaiiensis. All five studied isolates ofHeterorhabditiswere identified asH. indicaandH. bacteriophora. In both phylogenetic trees, the intra-specific variability level was different among clades for some species. The description of the new species (PAL10 isolate) would need further morphometric characterisation, morphologically identification and cross-breeding studies.

Virulence of new strain of Heterorhabditis bacteriophora from Croatia against Lasioptera rubi

“…Nguyen et al (2008) reported that H. bacteriophora and H. georgiana are in close relationship. Iqbal et al (2016) constructed a phyllogram with heterorhabditid species and found similar results to our study, the close relationship of H. bacteriophora strain with H. georgiana. It is very difficult to distinguish these two species.…”

“…Heterorhabditis bacteriophora is ubiquitous in diverse habitats, and has been documented from all agricultural parts of the world (Hunt & Nguyen 2016). From ex-Yugoslavian republics, Croatia's neighbouring countries, H. bacteriophora was the only heterorhabditid species reported and found only in Slovenia (Laznik et al 2009) and Bosnia and Herzegovina (Iqbal et al 2016). In Hungary, the bordering country to Croatia's continental region, H. bacteriophora, H. megidis, and H. downesi are reported (Tóth 2006).…”

First report of entomopathogenic nematode Steinernema feltiae (Rhabditida: Steinernematidae) from Croatia

“…In Southeastern Europe there are records of EPNs from several countries only: Slovenia (Laznik et al, 2009), Bosnia and Herzegovina (Iqbal & Ehlers, 2016), Serbia (Tallosi et al, 1995), Bulgaria (Shishiniova et al, 1997), Greece (Menti et al, 1997), and Albania (Tarasco & Poliseno, 2005). An increasing trend in research and commercialization of EPNs has been observed throughout the world (Kaya et al, 2006).…”

Comparing high throughput sequencing and real time qPCR for characterizing entomopathogenic nematode biogeography

“…For HTS purposes and the proper identification of target organism, ribosomal DNA and ITS region were amplified (average length >730bp) from bulk DNA extractions using universal primers TW81 (5'-GTTTCCGTAGGTGAACCTGC-3') as forward primer and AB28 (5'-ATATGCTTAAGTTCAGCGGGT-3') as reverse primer (Iqbal et al, 2016). Primers were modified to include an overhang adapter sequence to enable sequencing, following the Illumina protocol for the 16S rRNA gene sequencing in microbial samples (16S Library Preparation Protocol at http://support.illumina.com).…”