Isolation and characterization of Bacillus thuringiensis strains with insecticidal activity to lepidopteran pests

Sunday, November 16, 2014: 2:00 PM
Portland Ballroom 255 (Oregon Convention Center)
You-Kyoung Lee , Department of Applied Biology, Chungnam National University, Daejeon, South Korea
Na-Young Jin , Department of Applied Biology, Chungnam National University, Daejeon, South Korea
Jun-Hack Jeon , Department of Applied Biology, Chungnam National University, Daejeon, South Korea
Yu-Seop Kim , Department of Applied Biology, Chungnam National University, Daejeon, South Korea
Bo-Ram Lee , Department of Applied Biology, Chungnam National University, Daejeon, South Korea
Mi-Ja Seo , Department of Applied Biology, Chungnam National University, Daejeon, South Korea
Young-Nam Youn , Department of Applied Biology, Chungnam National University, Daejeon, South Korea
Yong-Man Yu , Department of Applied Biology, Chungnam National University, Daejeon, South Korea
Bacillus thuringiensis strains were isolated from 26 soils samples collected at the Yeong-Dong and Ok-cheon, ChungBuk province and selected strains with high toxicities against to difficult to control lepidopteran pests. Eight B. thuringiensis isolates with spore and crystal inclusion protein were selected among several isolates from 26 soil samples. Eight B. thuringiensis strains isolated investigated insecticidal activities against Spodoptera litura, Spodoptera exigua, Plutella xylostella, and Aedes aegypti. So, CAB565 and CAB 566 strains showing the high insecticidal activities in 4 tested insect species were selected. It was confirmed that B. thuringiensis CAB565 and CAB566 produced typical bipyramidal crystals with insecticidal activity against lepidopteran pests during sporulation using phase contrast microscope and Scanning electron microscope. As a result of identification of two strains by flagellin C gene, CAB565 strain was showed B. thuringiensis subsp. kurstaki and CAB566 strain was showed B. thuringiensis subsp. aizawai. CAB566 strain showed the highest insecticidal activity as 4.6X105(cfu/ml) with LC50 value against Spodoptera litura 3rd larva. CAB566 strain showed a the highest insecticidal activity as 5.6X105(cfu/ml) with LC50 value against Spodoptera exigua 3rd larva. As compared with insecticidal activities between two strains and the marketing microbial insecticide, these two isolates, CAB565 and 566 showed excellent activities against insect pests tested. In SDS-PAGE result, CAB565 and CAB566 stains showed 130kDa protein band. Also, when these two isolates reacted with midgut juice of S. exigua and S. litura, 130kDa protein was resolved into approximately 65kDa. In a result of PCR analysis, it was confirmed that CAB565 strains have cry1Aa, cry1Ac, cry1I genes and CAB566 have cry1Aa, cry1C, cry1D, cry1I genes. As a result of plasmid DNA patterns, KB099 strain had 5 plasmid DNA and CAB566 strain had 10 plasmid DNA bands. KB098 strain had 9 plasmid DNA and CAB566 strain had 7 plasmid DNA.

Key words : Baciilus thuringiensis, Spodoptera litura, Spodoptera exigua, Plutella xylostella

See more of: P-IE SS: Biological Insect Control - Ready for a Breakthrough?
See more of: Section Symposia
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