Comparison between bacteriophage typing and serotyping for the differentiation of Bacillus sphaericus strains

Eleven bacteriophages were isolated using mosquito pathogenic strains of B. sphaericus as hosts. The phage morphology and host range on five DNA homology groups including 16 mosquito pathogenic and 32 non-pathogenic strains were determined. the same bacterial strains were studied serologically for their flagellar agglutination by antisera representing eight serotypes: six antisera prepared against the reference strains for the DNA homology groups and two others against selected mosquito pathogenic strains. Two new serotypes have been determined among the non-pathogenic strains. Both phage typing and serotyping identified subgroups within the IIA homology group which contains the mosquito pathogens. The same bacterial strains were found in the subgroups established by both methods. These subgroups often paralleled difference in the level of toxicity of the strains for mosquito larvae.