Biosynthesized silver nanoparticles from Pedilanthus tithymaloides leaf extract with anti-developmental activity against larval instars of Aedes aegypti L. (Diptera; Culicidae)

Mosquitoes transmit dreadful diseases to human beings wherein biological control of these vectors using plant-derived molecules would be an alternative to reduce mosquito population. Aqueous leaf extract and green synthesized silver nanoparticles (Ag NPs) from Pedilanthus tithymaloides (L.) Poit. were investigated for their efficacy against the dengue vector Aedes aegypti L. (Diptera; Culicidae). The biologically synthesized Ag NPs were characterized by UV-vis spectrum, X-ray diffraction, Fourier transform infrared, and surface characteristics by atomic force microscopy. Further, on exposure of the larvae to varying concentrations of aqueous leaf and Ag NPs for 24 h, these Ag NPs showed 100 % mortality from first to fourth instars and pupae of A. aegypti at 0.25 %, which is the highest concentration, tested, wherein it was the lowest concentration of aqueous leaf extract alone which showed only 10-18 % of mortality. Lethal concentration (LC50) values of Ag NPs against the larval and pupal stages were 0.029, 0.027, 0.047, 0.086, and 0.018 % with no mortality in control. These results suggest that the use of P. tithymaloides silver nanoparticles can be a rapid, environmentally safer bio-pesticide which can form a novel approach to develop effective biocides for controlling the target vector.