Bacillus thuringiensis serovar higo (flagellar serotype 44), a new serogroup with a larvicidal activity preferential for the anopheline mosquito

Eight strains of Bacillus thuringiensis, isolated in Japan, formed spherical parasporal inclusions and exhibited low to moderate larvicidal activities for two mosquito species, Anopheles stephensi and Culex pipiens molestus, but not for another dipteran, Telmatoscopus albipunctatus, or two lepidopterans, Bombyx mori and Hyphantria cunea. The anopheline toxicity (LC50 = 6.3 micrograms ml-1) was > 10 times greater than the activity on the Culex mosquito. These strains were assigned to a previously undescribed flagellar (H) antigenic group. On the basis of the representative strain, 92-KU-137-4, a serogroup with H antigen 44, Bacillus thuringiensis serovar higo was established as new.