Evaluating the larvicidal effect of Bacillus Thuringiensis M-H-14 on Aedes aegypti larvae under laboratory and semi-field conditions in Southern Iran

The use of larvicides is a vital part of integrated vector control aimed at managing invasive Aedes mosquitoes. However, there is an urgent need for safe alternative control agents to replace chemical larvicides, as the effectiveness of these chemicals has been diminished by the emergence of resistance in Aedes populations. We evaluated the performance of granule, suspension, and wettable powder formulations of Bacillus thuringiensis serotype M-H-14 (Bioflash^®) in the laboratory at concentrations of 17, 0.17, 0.0017, and 0.000017 mg/L on Aedes aegypti in Bandar Abbas City, Hormozgan Province, Iran, and determined the LC₅₀ and LC₉₉ values. Subsequently, we assessed the initial efficacy and residual activity of the wettable powder formulation under semi-field conditions. The results showed that both the wettable powder and suspension formulations achieved 100% mortality of Ae. aegypti larvae when tested in laboratory studies at the highest concentration. In contrast, the granule formulation only resulted in 49% mortality. During the semi-field phase, the wettable powder formulation demonstrated residual activity lasting 2 to 14 days. The results of this research could greatly assist in creating a comprehensive vector-borne disease control program, especially in tackling insecticide resistance in Ae. aegypti in Iran.