LABORATORY AND FIELD-EVALUATION OF EFFICACY OF VECTOBAC(R)12AS AGAINST CULEX SITIENS (DIPTERA, CULICIDAE) LARVAE

Laboratory bioassay studies of the efficacy of VectoBac(R)12AS (active ingredient: 1,200 International Toxic Units [ITU]/mg Bacillus thuring iensis var, israelensis) against field-collected late 3rd/early 4th-in star larvae of Culex sitiens indicated excellent control potential. A 95% lethal concentration (LC95) value of 1.381 x 10(7) ITU was calcula ted, which equated to a dosage of 0.011 liters/ha. This dosage represe nted 1.8% of the recommended lowest dosage rate for the product. A fie ld trial of VectoBac 12AS against late 3rd/early 4th-instar field spec imens of Cx. sitiens in floating mesh cylinders was then conducted in salt-marsh pools near Coomera Marina, southeast Queensland, Australia. At a rate of 0.5 liters/ha, 100% mortality of Cx. sitiens larvae was recorded at 24 h posttreatment.