Bacillus thuringiensis var. israelensis (Bti) Provides Residual Control of Aedes aegypti in Small Containers

We examined the use of megadoses of VectoBac WG for residual control of Aedes aegypti in 2-L plastic buckets. Doses of 10x, 20x, and 50x the recommended rate of 8 mg/L provided >= 90% control for 8, 8, and 23 weeks, respectively. There was no significant difference in mortality between dry (neat) or aqueous mixture of VectoBac WG. Pretreatment of dry containers up to 8 weeks before flooding did not significantly decrease efficacy through 11 success weeks. Thus, megadoses of dry formulations of Bti can be used for residual control of Ae. aegypti in small containers. Furthermore, these doses use small amounts of product (0.08-0.4 g/L) that is more practical to measure than the minute amounts (0.008 g/L) required by the recommended rate, and cost US$2.18 to treat 50 Cairns yards containing an average total of 80 containers. This method could also be used to control Aedes albopictus.