Prospecting for Scarabid Specific Bacillus Thuringiensis Crystal Toxin Cry8 Gene in Sugarcane Ecosystem of Tamil Nadu, India

In the present study, we report the occurrence of cry8 positive isolates of Bacillus thuringiensis (Bt) in selected white grub, Holotrichia serrata F. (Coleoptera: Scarabaeidae), endemic soils of sugarcane ecosystem and other places in Tamil Nadu. Out of the 66 soil samples collected and screened for white grub specific Bt, 74 isolates of the bacterium, all containing only spherical crystal toxin, were identified. PCR screening of these isolates with cry8 gene universal primer revealed six isolates to be positive. Further, the amplicon of a 370 bp band, amplified with another set of degenerate primer designed based on the conserved sequence of cry8 genes, was sequenced from four isolates. Multiple sequence alignment revealed the gene sequences to be the same for all the isolates. The present report of the availability of cry8 positive Bt isolates opens the avenue for controlling white grubs through transgenic research.