Keshari, NishiMALLIKARJUN, GURRAM2023-02-272023-02-272021M/NEMA/386/2019-20https://krishikosh.egranth.ac.in/handle/1/5810194578Two isolates of entomopathogenic nematodes, labelled DA-1 and OC-1, were isolated during survey conducted in Pusa Farm, RPCAU, Pusa, Samastipur, Bihar using insect baiting technique. Morphological studies and molecular data confirmed these isolates as Steinernema abbasi and Oscheius sp., making this the first report of EPNs from Bihar. Bioefficacy experiments were conducted in laboratory to test the pathogenicity of the native EPN isolate, Steinernema abbasi at concentrations, 10, 50, 100, 500 and 1000 IJs against five different instars of two lepidopterous pests viz., Tobacco cutworm, Spodoptera litura and Oriental armyworm, Mythimna seperata. The test inoculum of 1000 infective juveniles (IJs) / larva was most effective causing mortality of all instar larvae at 24 h. Nematode multiplication rate in insect cadaver was directly proportional to the size/ instar of larva. The 5th instar larva resulted in highest yield of IJs, followed by 4th, 3rd, 2nd, and 1st instars larvae of both pests at all the inoculum levels used in the study. As these two isolates of EPNs are native to Pusa farm and have shown satisfactory bioefficacy potential, these can be exploited for the management of target crop insect pests of the region. However, further studies are required regarding their life cycle, host range, virulence potential and survival capacity under extreme environmental conditions.EnglishThesis