Molecular characterisation of novel isolates of entomopathogenic nematodes
Iqbal, Mudassir; Ehlers, Ralf-Udo; Waeyenberge, Lieven
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 the Steinernema genus and only few isolates belong to the Heterorhabditis genus. The phylogenetic relations of Steinernema and Heterorhabditis species were analysed by utilising the maximum likelihood method. In the Steinernema phylogenetic tree, 99 isolates formed five major, moderately or highly reinforced clades: clade I: affine-intermedium group; 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% with S. vulcanicum (accession number: GU929442), supporting the possible designation of a new species. In the Heterorhabditis phylogenetic 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 of Heterorhabditis were identified as H. indica and H. 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.
Heterorhabditidae; ITS; nematode isolates; PCR; phylogeny; rDNA; sequence analysis; Steinernematidae
2016, Volume: 18, pages: 277-291
Publisher: BRILL ACADEMIC PUBLISHERS
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