author(s)
Babita Dhirta, Anju S Khanna, PL Sharma and Mohinder Singh

abstract
Pathogenicity of Heterorhabditis bacteriophora Poinar, was tested against last instar larva of rice moth, Corcyra cephalonica Stainton, greater wax moth, Galleria mellonella Linnaeus, silkworm, Bombyx mori Linnaeus, tobacco caterpillar, Spodoptera litura Fabricius, and white grub, Brahmina coriacea Hope. Among the test insects, larvae of C. cephalonica and G. mellonella were found to be the most susceptible to the infective juveniles (IJs) of H. bacteriophora, in which 50-100% mortality was incurred at 48 hours of exposure. B. mori and S. litura were comparatively less susceptible with 30-80 % mortality at exposure of 48 hours. The least susceptible among the insects under reference was B. coriacea whose larvae remained alive up to 72 hours at the highest inoculum treatment of 160 H. bacteriophora IJs/ larva. Cent per cent larval mortality could be attained only at the highest level of inoculum. Dose - mortality response of the test insects against H. bacteriophora also revealed different LD50 values for the referred insects. LD₅₀ for C. cephalonica and G. mellonella at 24 hours was found to be 33.38 and 79.99 IJs/ larva respectively, whereas it was 25.18 and 20.26 IJs/larva for S. litura and B. mori respectively at 72 hours after treatment of H. bacteriophora at different doses. However, it was 40.28 for B. coriacea after 144 hours of treatments. LD₉₅ values were 453.18, 527.80, 291.82, 453.17 and 507.92 for Corcyra, Galleria, Spodoptera, Bombyx and Brahmina respectively at different exposure time.