Vol. 2, Issue 2, Part A (2016)

Abstract
Two Bacillus thuringiensis isolates GM17 and GM21 were evaluated against lepidopteran insect pest Amsacta albistriga. These isolates produced various crystal inclusions with bipyramidal, spherical and cuboidal shape which confirmed by phase contrast microscopy. SDS-PAGE analysis revealed both isolates produced different Cry proteins in the range of 130 KDa to 50 KDa. Insect bioassay were carried out to determine LC₅₀against second instar larvae of Amsacta albistriga. LC₅₀value was found 0.055 ngml^-1for Btk-HD-1 while for Bt isolates GM17 and GM21, LC₅₀values were found 0.017 ngml^-1 and 0.027 ngml^-1 respectively. Phylogenetic analysis of cry1Acgene sequence of GM17 isolate was found point mutation in domain II which can be used for domain swapping and cry2 gene of GM21 to gene pyramiding strategies for insect resistance management.