LARVICIDAL TOXICITY OF JAPANESE BACILLUS-THURINGIENSIS AGAINST THE MOSQUITO ANOPHELES-STEPHENSI

Japanese isolates of Bacillus thuringiensis were screened for larvicid al activity against the mosquito Anopheles stephensi, the urban malari a vector of the Indian subcontinent. Among more than 30 strains identi fied, larvicidal activity causing >80% mortality in 72 h was demonstra ted for 41/1449 (2.8%) isolates. The majority of strains and isolates (97.2%) exhibited little or no larvicidal activity. Anopheles-active s trains belonged to more than 12 H serotypes. especially H3ade (serovar fukuokaensis) and H44 (serovar higo). SDS-PAGE profiles of inclusion proteins showed 4 distinct types among 6 active strains examined. The most active Japanese isolates were H20 strain 89-T-34-14 (LC50 4.4 mu g/ml) and H44 serovar higo strain 74-E-45-24 (LC50 7.6 mu g/ml), respe ctively, 13-fold and 23-fold less active than the international standa rd H14 serovar israelensis (LC50 0.33 mu g/ml).