Another Bacillus sphaericus serotype harbouring strains very toxic to mosquito larvae: serotype H6.

Ten isolates of Bacillus sphaericus from Ghana, very toxic to mosquito larvae, have been identified as belonging to serotype H6. These isolates can be represented by the head-group strain IAB59. They form crystals at the sporulation stage. Their larvicidal effect on Culex pipiens and Anopheles stephensi larvae is as high as that of the most toxic strains already known, e.g. 1593 and 2362 (serotype H5a,5b) and 2297 (serotype H25). Spore-crystal extracts of all these strains contain a 43-Kd polypeptide immunologically related to the 43-Kd polypeptide from strain 2362 described by other authors.