Bio-physical Characterization of Poly-dispersed Silver Nanocrystals Fabricated Using Carissa spinarum: A Potent Tool Against Mosquito Vectors

In this research, green synthesis of silver nanoparticles (Ag NP) using a cheap, aqueous leaf extract of Carissa spinarum has been investigated. Bio-reduced Ag NP were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. The acute toxicity of C. spinarum leaf extract and biosynthesized Ag NP was evaluated against larvae of the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. Both the C. spinarum leaf extract and Ag NP showed dose dependent larvicidal effect against all tested mosquito species. Compared to the leaf aqueous extract, biosynthesized Ag NP showed higher toxicity against A. subpictus, A. albopictus, and C. tritaeniorhynchus with LC50 values of 8.37, 9.01 and 10.04 mu g/mL, respectively. Biosynthesized Ag NP were found safer to non-target organisms Diplonychus indicus, Anisops bouvieri and Gambusia affinis, with respective LC50 values ranging from 424.09 to 647.45 A mu g/mL. Overall, this study highlights the concrete potential of C. spinarum as a potential bio-resource for rapid, cheap and effective synthesis of mosquitocides.