Synthesis of silver nanoparticles from Azadirachta indica--a most effective method for mosquito control

Mosquitoes transmit major communicable diseases such as dengue, malaria, filariasis, Japanese encephalitis, chikungunya, and so on. Vector control is important in epidemic disease situations as there is an urgent need to develop new and improved mosquito control methods that are economical and effective yet safe for non-targeted organisms. In the present study, silver nanoparticles (AgNPs) were synthesized from the aqueous leaf extract of neem plant (Azadirachta indica), and their effects on mosquito vectors (Aedes aegypti and Culex quinquefasciatus) were assessed. The synthesised AgNPs were characterized by UV-vis spectroscopy, scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction analysis (XRD). The nanoparticles have maximum absorption at 442 ± 1.5 nm with an average size of 41-60 nm. The XRD data showed six well-defined diffraction peaks, corresponding to a relative intensity of the crystal structure of metallic silver 36.42, 100.00, 53.70, 14.20, 16.05, and 6.79, respectively. The FT-IR data showed strong prominent peaks in different ranges, reflecting its complex nature. The mosquito larvae were exposed to varying concentrations of AgNPs synthesized from the neem leaves under investigation (0.07-25 mg/l) for 24 h; this revealed larvicidal activity of AgNPs with LC50 and LC90 values of 0.006 and 0.04 mg/l for A. aegypti, respectively. Further, the LC50 and LC90 values were also identified as 0.047 and 0.23 mg/l for Cx. quinquefasciatus, respectively. The result obtained from this study presents biosynthesized silver nanoparticle from A. indica as the biolarvicidal agent with the most potential for mosquito control.