Detection and identification of Steinernematid and Heterorhabditid nematodes (enthomopathgenic nematodes) in cultivated and forestrial soils in Iran.

Entomopathogenic nematodes (EPN) belonging to Heterorhabditidae and Steinernematidae families are obligate parasites of soil-inhabiting insects and have good potential as biological control agents for a wide range of insect pests. In order to detect and identify EPN in Iran totally 421 soil samples were collected from different habitats from Tehran, Mazandaran, Golestan, Gilan, Esfahan, Chahar mahaal–va- Bakhtiyari, West Azarbaijan, East Azarbaijan, Ardabil, Kordestan, Kermanshah, Lorestan, Hamadan, Khuzestan, Sistan-va-Blouchestan provinces. The soil samples were bioassayed with the great wax moth caterpillars (Galleria mellonella). EPN were recovered from 18 (4.3%) of the soil samples. The positive samples were recovered from Tehran, Gilan, Mazandaran, Golestan, Chahar mahaal–va-Bakhtiyari,West Azarbaijan, Ardabil, Kordestan, Lorestan and Hamadan provinces. They were more frequently found in samples taken from fruit orchards, woodlands and grasslands. Morphological and morphometrical studies of infective juveniles and males were done by light microscope. For molecular and phylogenetic studies the ITS1-5.8S-ITS2 regions were amplified by PCR and the sequences of this regions were determined. The amplification yielded a fragment of about 700-800 bp length in all populations. The obtained sequences were analysed by comparing the sequences with published sequences deposited in NCBI GeneBank. Based on these studies the recovered isolates were identified as Heterorhabditis bacteriophora and two species of Steinernema, viz. S. feltiae and unidentified Steinernema sp. belonging to "affine group". Morphological and morphometrics characters of the H. bacteriophora and S. feltiae corresponded well with the original description of these species. Comparison of sequences of Iranian population of S. feltiae with other Iranian isolates of S. feltiae and world isolates showed 90-92% and 83-91% similarities respectively. The similarities of H. bacteriophora isolates recovered from the present study were 95- 99% and 69-97% with other Iranian isolates and world isolates of H. bacteriophora. Steinernema sp. showed remarkable differences in morphological and morphometrics characters with other species of "affine-group" as well as differences in the sequences of rDNA-ITS regions, the differences are exceeding the level of intra-specific variability reported for the species in the group, most probably Iranian population represents undescribed steinernematid species. Among the recovered entomopathogenic nematodes species H. bacteriophora was the most frequently encountered species and was isolated from 77.7% of soil samples. H. bacteriophora 􀀀 􀀀 and S. feltiae were reported from several regions in the world and are being applied as potential biological control of many insect pests. Identification of these species in country may contribute to the use of native isolates of entomopathogenic nematodes in biological control. Isolating of EPN from several provinces indicates that these nematodes are widely spread in several provinces and could be used in future biological control programs and integrated pest management on important insect pests. Keywords: Entomopathogenic nematodes, Heterorhabditis bacteriophora, Steinernema feltiae