Abstract

Toxicity study for indigenous Bacillus thuringiensis isolates from Malang city, East Java, on Aedes aegypti larvae have been done. In order to maintain the sustainability of the local bacteria which have effectively controlled population of mosquito larvae, it is necessary to observe the toxicity tests for local bacteria from other places around East Java. The aim of this study was to investigate the toxicity of indigenous Bacillus thuringiensis isolates from East Java for controlling Aedes aegypti larvae. Methods: soil samples were taken from Blitar, Bondowoso, Bangkalan, Ponorogo, Tulung Agung, Lamongan, and Surabaya districts. Phenotypic characteristics of the isolates were obtained with the simple matching method. The growth and prevalence of spores were determined by the Total Plate Count method, and toxicity tests were also performed on the third instar larval stage. The percentage of larval mortality was analysed using probit regression. The LC50 was analysed by ANOVA, and the Tukey HSD interval was 95%. Results: the seven indigenous B.thuringiensis isolates were found in Blitar , Bondowoso, Pamekasan, Ponorogo, Tulung Agung, Lumajang, and Surabaya districts were toxic to the third instar larvae. The Surabaya isolates had the highest spore prevalence and the most effective at killing Aedes aegypti larvae.