First Report and Comparative Study of (Rhabditida: Steinernematidae) and its Symbiont Bacteria from Subcontinental India.

Two populations (CS19 and CS20) of entomopathogenic nematodes were isolated from the soils of vegetable fields from Bijnor district, India. Based on morphological, morphometrical, and molecular studies, the nematodes were identified as . This work represents the first report of this species in India. The infective juveniles (IJs) showed morphometrical and morphological differences, with the original description based on longer IJs size. The IJs of the Indian isolates possess six ridges in their lateral field instead of eight reported in the original description. The analysis of ITS-rDNA sequences revealed nucleotide differences at 345, 608, and 920 positions in aligned data. No difference was observed in D2-D3 domain. The COI gene was studied for the first time as well as the molecular characterization of their symbiont using the sequences of recA and gyrB genes revealing as its symbiont. These data, together with the finding of , suggest that this bacterium is widespread among South Asian nematodes from the "" group. Virulence of both isolates was tested on The strain CS19 was capable to kill the larvae with 31.78 IJs at 72 hr, whereas CS20 needed 67.7 IJs.