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 Steinernema surkhetense. 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 S. surkhetense COI gene was studied for the first time as well as the molecular characterization of their Xenorhabdus symbiont using the sequences of recA and gyrB genes revealing Xenorhabdus stockiae as its symbiont. These data, together with the finding of X. stockiae, suggest that this bacterium is widespread among South Asian nematodes from the ''carpocapsae'' group. Virulence of both isolates was tested on Spodoptera litura. The strain CS19 was capable to kill the larvae with 31.78 IJs at 72 hr, whereas CS20 needed 67.7 IJs.

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The American bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a highly destructive agriculture pest of worldwide importance. The aim of the present study was to infect H. armigera larvae with entomopathogenic nematode juveniles for hematological study of proteins and encapsulation responses to evaluate using this nematode for the management of this pest. Total protein estimation and the electrophoretic profiling carried out in the hemolymph showed a high pathogenicity of Steinernema abbasi to H. armigera. The control group survived and succeeded to develop to adults, while the infected ones died within 24 h. An increase in the protein contents in the total and plasma hemolymph was observed just after 3 h of infection with an increase at 6 h and 9 h as symptoms of early defence of the insect. SDS-PAGE profile also showed an evolvement of a protein band of 46 kDa. No selfassociation or aggregation and binding of other proteins were found in the hemolymph as revealed by Native-PAGE. The encapsulation avoidance rate of nematode juvenile gave good results with (> 33%) in 2 IJs/larva to 5% in 20 IJs/ larva doses at24 h post infection. Loss of hemolymph proteins continued for more than 24 h with a very low recognition of nematode rate in hemolymph, followed by the death of larvae within 48 h, which proved the high pathogenicity of S. abbasi and suppression of host immune system of H. armigera.