Ubiquity of<i>Bacillus thuringiensis</i>on phylloplanes of arboreous and herbaceous plants in Japan

Abstract

A total of 120 Bacillus thuringiensis strains was isolated from phylloplanes of 35 species of arboreous and herbaceous plants in an area of northern Kyushu, Japan. The isolates belonged to at least 17 serotypes and the group of H serotype 3 was predominant. Twenty strains were untypable by the existing reference H antisera and 47 were untestable due to autoagglutination or poor motility. Of the 120 isolates, 25 produced bipyramidal parasporal inclusions and the others, spherical or irregular-shaped. Insecticidal activity against mosquitoes (Culex pipiens molestus and Anopheles stephensi) and/or diamondback moth, Plutella xylostella, was associated with 28 isolates (23·3%). Overall results revealed that: B. thuringiensis is ubiquitous on a variety of plants; bacterial flora on phylloplanes consists of highly heterogeneous H serogroups; and there is little correlation between plant species and phenotypes of B. thuringiensis isolates.