Detection of the cry1 gene in Bacillus thuringiensis isolates from agricultural fields and their bioactivity against two stored product moth larvae

Sixty Bacillus spp. isolates were obtained from different agricultural fields in Kayseri province using selective media. Total DNA was isolated and analyzed by PCR using cry1 general primers. Of the 60 tested isolates, 17 carried the cry1 gene. B. thuringiensis subsp. kurstaki and all other isolates exhibited approximately 19-kb plasmid bands. In addition to the 270-bp band, the standard strain and isolate I47 yielded 180-bp PCR products. The isolates and standard strain were toxic to Ephestia kuehniella Zeller and Plodia interpunctella Hubner larvae. Insecticidal activity of isolates I36, I37, and I40 against Ephestia kuehniella was higher than that of the standard strain when 10^6 spore-crystals mL^–1 was used. LC99 values for isolates I36, I37, and I40 were 6.46, 6.28, and 6.24 for E. kuehniella, respectively, and these isolates were also effective against Plodia interpunctella larvae. LC99 values for isolates I36 and I40 were 6.69 and 5.07 for P. interpunctella, respectively. The results clearly show that isolates I36, I37, and I40 were effective at lower doses, as compared to the others.