title: Toxicity studies for indigenous Bacillus thuringiensis isolates from Malang City, East Java on Aedes aegypti larvae.
abstract: OBJECTIVE
  To investigate the toxicity of indigenous Bacillus thuringiensis (B. thuringiensis)isolates from Malang City for controlling Aedes aegypti (Ae. aegypti) larvae.
  
  
  METHODS
  Soil samples were taken from Purwantoro and Sawojajar sub-districts. Bacterial isolation was performed using B. thuringiensis selective media. 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 of Ae. aegypti. The percentage of larval mortality was analysed using probit regression. The LC50 was analysed by ANOVA, and the Tukey HSD interval was 95%.
  
  
  RESULTS
  Among the 33 selected bacterial isolates, six were obtained (PWR4-31, PWR4-32, SWJ4-2b, SWJ4-4b, SWJ-4k and SWJ5-1) that had a similar phenotype to reference B. thuringiensis. Based on the dendrogram, all of the bacterial isolates were 71% similar. Three isolates that had a higher prevalence of reference B. thuringiensis were PWR4-32, SWJ4-4b and SW5-1, of which the spore prevalence was 52.44%, 23.59%, 34.46%, respectively. These three indigenous isolates from Malang City successfully killed Ae. aegypti larvae. The PWR4-32 isolates were the most effective at killing the larvae.
  
  
  CONCLUSIONS
  Six indigenous B. thuringiensis isolates among the 33 bacterial isolates found in the Sawojajar and Purwantoro sub-districts were toxic to the third instar larvae of Ae. aegypti. The PWR4-32 isolates were identical to the reference B. thuringiensis and had 88% phenotype similarity. The PWR4-32 isolates had the highest spore prevalence (52.44%), and the early stationary phase occurred at 36 h. The PWR4-32 isolates were the most effective at killing Ae. aegypti larvae (LC50-72 h=2.3×10(8) cells/mL).
authors.affiliation: Graduate School for International Development and Cooperation (IDEC), Hiroshima University, Japan.
authors.forename: Zulfaidah Penata
authors.initials: ZP
authors.lastname: Gama
authors.forename: Nobukazu
authors.initials: N
authors.lastname: Nakagoshi
authors.lastname: Suharjono
authors.forename: Faridah
authors.initials: F
authors.lastname: Setyowati
mesh_terms: D000330:Aedes / Q000382:microbiology*; D000818:Animals; D001413:Bacillus thuringiensis / Q000302:isolation & purification / Q000502:physiology*; D061046:Biological Control Agents; D007214:Indonesia; D007306:Insecticides; D007814:Larva / Q000382:microbiology; D007928:Lethal Dose 50; D009032:Mosquito Control
chemical_list: D061046:Biological Control Agents; D007306:Insecticides
keywords: Aedes aegypti; Bacillus thuringiensis; LC50; Toxicological studies