A novel Bacillus thuringiensis strain and its pathogenicity against three important pest insects

A highly pathogenic Bacillus thuringiensis (Bt) strain was isolated from a soil sample in Turkey and characterized in terms of both its 16S-ITS rDNA region and cry gene content. This strain (SY49.1) harboured several cry genes producing crystalline inclusions known to have toxicity on lepidopteran, dipteran and coleopteran pests. The 16S-ITS sequence analysis of Bt SY49.1 showed 98% similarity to Bt serovar andalousiensis BGSC 4AW1. The larvae of Ephestia kuehniella and Plodia interpunctella were treated with a spore-crystal mixture of this strain in the dose range of 50–1000 μg g−1. Mortality rates were higher than 90% at the highest concentration for these pests. For Tribolium castaneum much higher concentrations were needed than with lepidopteran pests larvae. At the highest concentration tested of 10 mg g−1, about 62% mortality was obtained. It was concluded that this native strain of Bt could be used as an effective biocontrol agent against various lepidopteran pests.

► SY49.1 is a novel Bacillus thuringiensis strain.
► The 16S-ITS rDNA sequence analysis of SY49.1 showed 98% similarity to Bt serovar andalousiensis.
►  SY49.1 has similar and different plasmid and protein bands compared to Btk HD1, Btt, Bta and Bti strains.
► Bt SY49.1 has high insecticidal effect on lepidopteran pests Ephestia kuehniella and Plodia interpunctella.
► Bacillus thuringiensis SY49.1 strain could be used for developing effective biopesticides.