Shoji Asano

Insecticidal spectrum of a novel isolate of Bacillus thuringiensis serovar japonensis

Abstract A newly isolated strain, designated Buibui, belonging to Bacillus thuringiensis serovar japonensis had potent larvicidal activity against the scarabaeids Anomala cuprea Hope and Popillia japonica Newman. Preliminary tests indicated that other scarabaeid larvae including A. albopilosa Hope, A. rufocuprea Motschulsky, A. daimiana Harold, A. schonfeldti Ohaus, Mimela splendens (Gyllenhal), and Blitopertha orientalis (Waterhouse) were equally susceptible to strain Buibui. However, the strain showed no insecticidal activity against larval lepidopteran insects including Bombyx mori (L.) (Bombycidae), Plutella xylostella (L.) (Plutellidae), Spodoptera litura Fabricius, S. exigua Hubner (Noctuidae), and Adoxophyes sp. (Tortricidae) and coleopterans, Allomyrina dichotoma L. (Scarabaeidae) and Henosepilachna vigintioctopunctata Fabricius (Coccinellidae). At 14 days post-treatment, the LC50 and LC95 of the δ-endotoxin against the cupreous chafer, A. cuprea, were estimated by probit analysis as 0.098 ± 0.019 and 0.29 ± 0.086 μg protein/g compost, respectively. Strain Buibui showed no β-exotoxin activity.

Cloning, heterologous expression, and localization of a novel crystal protein gene from Bacillus thuringiensis serovar japonensis strain buibui toxic to scarabaeid insects.

RecombinantEscherichia coli strains harboring pAG1, pAG2, pKBB100, and pKBB101 were cloned by using antiserum constructed against 130-kDa crystal protein antigen ofBacillus thuringiensis serovarjaponensis strain Buibui. DNAs in the recombinant strains hybridized to the 26-base oligonucleotide probe corresponding to N-terminal amino acids of the 130-kDa crystal protein of strain Buibui. Cultures of the recombinant strains were toxic to larvae of the cupreous chafer,anomala cuprea. Furthermore, the production of the 130-kDa polypeptide was demonstrated in the cells harboring pAG1 and pAG2 by immunoblot analysis with antiserum against the 130-kDa crystal protein. Southern hybridization analysis showed that the 130-kDa crystal protein gene is located on the chromosomal DNA of strain Buibui. On the other hand, DNA probes derived fromcryIA(a) andcryIIIA genes did not hybridize to the DNA of strain Buibui.