A novel method for evaluating the particle distributional behavior of a spray-dried technical concentrate and a water-dispersible granule formulation of Bacillus thuringiensis subsp. Israelensis in an aqueous column

Control of mosquito larvae in seasonal wetlands on a wildlife refuge using VectoMax CG

There is a great need for novel insecticides to control mosquitoes. VectoMax is a new mosquito larvicide that combines toxins from Bacillus thuringiensis subsp. israelensis (Bti) and Bacillus sphaericus (Bs), and is designed to provide extended mosquito control. We tested the initial efficacy and longevity of control of mosquitoes using one of the formulations, VectoMax CG, in a full-scale study conducted in seasonal wetlands. VectoMax CG was applied by air at 8.9 kg/ha to 3 wetlands and 3 others were untreated controls. VectoMax CG controlled Culex tarsalis through day 28 and showed activity against Aedes melanimon. Use of this dual-material, extended-action formulation could minimize inspection visits and reduce application costs compared to Bti and Bs alone, and its combination of toxins may forestall resistance development.

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.