Characterization of Bacillus thuringiensis subsp. aizawai CAB109 isolate with bioactivities to Spodoptera litura and Spodoptera exigua (Lepidoptera: Noctuidae)
Bacillus thuringiensis subsp. aizawai CAB109 isolated in Korea is known active against Spodoptera sp.. Especially, B. thuringiensis aizawai CAB109 isolates showed 100% mortality against Spodoptera litura and Spodoptera exigua. To screen highly active B. thuringiensis, the pathogenicity of B. thuringiensis CAB109 was compared with that of commercialized B. thuringiensis products. LC₅₀ values of CAB109, product TB-WP and product SC strains of B. thuringiensis were 1.3x10⁵, 2.3x10⁶ and 5.2x10⁵ cfu/㎖ against the 2nd larva of S. litura and 1.8×10⁴, 1.3×10⁶ and 1.5×10⁶ cfu/㎖ against the 2nd larva S. exigua, respectively. To determine new gene"s existence and absence, the plasmid DNA was extracted, and compared to that of B.t. aizawai HD-133. Both B. thuringiensis were not like plasmid DNA pattern. PCR technique was used to predict both plasmid DNA"s cry gene. PCR products analysis showed that B.t. CAB109 harbor Cry1Aa, Cry1Ab, Cry1C and Cry1D and B.t. HD-133 has Cry1Aa and Cry1Ab, respectively.