A strain of Bacillus thuringiensis subsp. galleriae containing a novel cry8 gene highly toxic to Anomala cuprea (Coleoptera: Scarabaeidae)

A strain of Bacillus thuringiensis (Bt) subsp. galleriae highly toxic to the cupreous chafer, Anomala cuprea, was isolated from a soil sample collected in Japan. The strain, SDS-502, produces a crystal consisting of a 130-kDa protein. The gene encoding the protein was cloned in Escherichia coli using antiserum directed to the protein. The gene was expressed in E. coli, producing a 130-kDa protein toxic to A. cuprea. Sequencing of the cloned gene indicated a typical Bt cry gene with substantial homology to cry8 genes. Based on the peptide sequence comparison, the gene found in SDS-502 was designated as cry8Da (AB089299). The cry8Da gene was highly expressed in SDS-502 in a laboratory scale bioreactor. The fermentation product of SDS-502 was formulated for soil application and tested in a peanut field for chafer control along with a chemical insecticide reference, a fenthion organophosphate granular formulation. Judging from the amount of undamaged nuts harvested from plots of different treatments, plots treated with SDS-502 had significantly better insect control than the untreated plots. The chemical insecticide plots showed no significant difference in nut damage from the Bt-treated or control plots.