INSECTICIDAL ACTIVITY OF THE PROTEIN ENCODED BY THE CRYV GENE OF BACILLUS-THURINGIENSIS KURSTAKI INA-02

A new host specificity was discovered with the insecticidal protein en coded by the cryV gene. The cryV gene was cloned from the Bacillus thu ringiensis kurstaki INA-02 strain, which was selected among a number o f B. thuringiensis isolates because of its high activity against Spodo ptera litura. Analyses by polymerase chain reaction (PCR) revealed tha t INA-02 contained the cryIA(a) and clyV genes. Since no Spodoptera ac tivity was observed with B. thuringiensis sotto, which contained only cryIA(a), insecticidal activity of the protein encoded by the cryV gen e was investigated with several insect species including S. litura. Fo r 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. litu ra and P. xylostella, suggestive that the protein contributes to the u nique activity of INA-02.