Insecticidal Activity of the Protein Encoded by the cryV Gene of Bacillus thuringiensis kurstaki INA-02

Abstract.

A new host specificity was discovered with the insecticidal protein encoded by the cryV gene. The cryV gene was cloned from the Bacillus thuringiensis kurstaki INA-02 strain, which was selected among a number of B. thuringiensis isolates because of its high activity against Spodoptera litura. Analyses by polymerase chain reaction (PCR) revealed that INA-02 contained the cryIA(a) and cryV genes. Since no Spodoptera activity was observed with B. thuringiensis sotto, which contained only cryIA(a), insecticidal activity of the protein encoded by the cryV gene was investigated with several insect species including S. litura. For bioassay, the cryV gene was highly expressed in an acrystalliferous B. thuringiensis strain, BT51. The CryV protein from BT51 was assayed against larvae of three lepidopteran species, Bombyx mori, S. litura, and Plutella xylostella. The protein was highly active against S. litura and P. xylostella, suggestive that the protein contributes to the unique activity of INA-02.