In vitro evaluation of native Bacillus thuringiensis (berliner) isolates against different insects

Evaluation of native strains of Bacillus thuringiensis (Berliner) isolates against different orders of insects and characterization of responsible Cry genes was carried out. Among the native isolates, BGC-1 showed the least LC₅₀ value of 5.24 μg/ ml and was comparable to the reference strain HD1 (2.89 μg/ ml) against tobacco caterpillar Spodoptera litura (Fabricius). The isolate RCM-1 recorded least LC₅₀ value of 4.69 μg/ ml against the housefly Musca domestica Linnaeus. One isolate viz., GHB-1 was found to be potential against both the larvae of S. litura and M. domestica. The isolate RCM-2 registered the least LC₅₀ value of 8.21 μg/ ml against grubs of red flour beetle Tribolium castaneum (Herbst). Several isolates had more than one Cry gene in them. Among them, 12 isolates (63.15%) were found to contain Cry3 genes, 11 isolates harbour Cry4 genes, five isolates had Cry1, Cry2 and Cry11 genes each and four isolates contain Cry7 genes each. Native isolate, GHB-1 had Cry1, Cry3, Cry4 and Cry11 genes.