Characterization of Local Bacillus thuringiensis Isolates and Their Toxicity to Ephestia kuehniella (Zeller) and Plodia interpunctella (Hubner) Larvae

Putative Bacillus thuringiensis isolates were obtained from soils of various agricultural fields. Of all the tested isolates U14.1, U14.2 and U14.5 were found to be positive for cry1C. Besides, U6.6, U14.1, U14.4 and U14.5 were determined to contain cry1B. These local isolates produced bi-pyramidal, spherical and cubical crystal proteins. U14.1, U14.4 and U14.5 isolates exhibited similar protein banding patterns with Btk producing around 45, 70 and 130 kDa proteins. However, U14.2 and U6.6 produced only 60 kDa major protein band. Some of the isolates also produced bands less than 45 kDa showing the presence of some other low molecular weight proteins. The results of this study demonstrated that isolates of Bt obtained from various agricultural fields may display toxicity against Ephestia kuehniella (Zeller) and Plodia interpunctella (Hubner) larvae. As a result, spore-crystal mixture of these isolates may play an important role in reducing the damage to stored products caused by these important pest insects