Distribution of Bacillus thuringiensis in sericultural farms of Fukuoka Prefecture, Japan.

概要

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A total of 124 crystalliferous sporeformers were isolated from the silkworm litters of 8 sericultural farms out of 38 farms of Fukuoka Prefecture, Japan. Most isolates were found to belong to Bacillus thuringiensis serotypes 3a: 3b (subsp. kurstaki), 4a: 4b (subsp. sotto or subsp. dendrolimus), 4a: 4c (subsp. kenyae), 7 (subsp. aizawai), 8a: 8b (subsp. morrisoni), 9 (tolworthi), and 19 (subsp. tochigiensis). Of these 7 serotypes, serotypes 3a: 3b, 4a: 4c, and 7 were predominantly detected. No concentrated occurrence of this bacterium was observed in any particular region. Coexistence of two different serotypes was evident in 3 sericultural farms. Three H serotypes and one untypable strain were simultaneously isolated from one farm. Most isolates were toxic to the silkworm larvae, Bombyx mori. For mosquito larvae, Aedes aegypti, serotype 7 isolates were more toxic than the isolates of the other serotypes. The above untypable isolate was nonmotile and produced large parasporal inclusions nontoxic to larvae of the silkworm and the mosquito. The four isolates belonging to serotype 19 produced spherical parasporal inclusions. These isolates were nontoxic to the silkworm but showed low toxicity to the mosquito.
九州病害虫研究会の論文