Mosquito Larvicidal and Pupicidal Activity of Tephrosia purpurea Linn. (Family: Fabaceae) and Bacillus sphaericus against, Dengue Vector, Aedes aegypti

Objective: The bio-efficacy of Tephrosia purpurea leaf extract and bacterial insecticide, Bacillus sphaericus larvicidal activity was assessed against the first to fourth instars larvae of Aedes aegypti, under the laboratory conditions. Methods: The plant material was shade dried at room temperature and powdered coarsely. T. purpurea and B. sphaericus show the various concentrations of larvicidal and pupicidal activity against various instars larvae of A. aegypti. Results: The LC₅₀ of T. purpurea against the first to fourth instars larvae were 139.24, 176.24, 219.28, 256.27, and 326.29 ppm and the 480.72, 541.21, 580.34, 672.20, and 762.80 ppm, respectively. B. sphaericus against the first to fourth instars larvae the LC₅₀ values were 46.16, 56.23, 69.82, 80.81 and 96.12 ppm and the LC₉₀ values 141.68, 172.46, 184.21, 193.31 and 218.16 ppm, respectively. However, the combined treatment of T. purpurea + B. sphaericus (1:2) material shows highest larvicidal activity of the LC₅₀ values 80.08, 82.21, 88.00, 92.21 and 98.16 ppm; The LC₉₀ values of 108.39, 118.71, 136.75, 149.02 and 153.24 ppm, against A. aegypti in all the tested concentrations than the individuals and clearly established that there is a substantial amount of synergist act. Conclusion: The present study reported that both T. purpurea and B. sphaericus materials could serve as a potential larvicidal agent. Since, A. aegypti is a container breeder vector mosquito this user and eco-friendly and low-cost vector control strategy could be a viable solution to the existing dengue disease burden. Therefore, this study provides first report on the mosquito larvicidal activity the combined effect of T. purpurea leaf extract and B. sphaericus against as target species of A. aegypti.