Laboratory efficacy and residual activity of a water dispersible granule formulation
of Bacillus thuringiensis israelensis (Bti) at the dosages of 3000, 6000 and 15000 ITU/L were
conducted in this study. The study was conducted in two different size containers, earthen
jar (45 L) and glass jar (3 L) with or without daily replenishment of 6 L and 0.3 L of water in
the earthen and glass jars, respectively. Results indicate that for both earthen jar and glass
jar evaluations, Bti at the tested dosages, performed effectively against Aedes aegypti, giving
a minimum of 42 days effective killing activity. When the dosage was increased from 3000
ITU/L to 6000 ITU/L or 15000 ITU/L, the effective periods of the Bti increased by an additional
one to three weeks. The Bti water dispersible granule provided better larvicidal activity with
replenishment of water compared with non-replenishment of water especially for the higher
dosage (15000 ITU/L).