Efficacy of silica and tin doped silica nanoparticles on the fourth larval instar of Culex pipiens

Abstract

Mosquito-borne diseases represent a growing health challenge over time. Therefore, silicon oxide and tin-doped silica, with three different ratios of tin, nanoparticles were synthesized via sol-gel/combustion and hydrothermal methods, respectively and evaluated for insecticidal activity against the 4th larval instar of Culex pipiens at different concentrations (25, 50, 100, 200, 400, and 800 ppm) in the sunlight, artificial light, and dark at different time intervals. The prepared nanoformulations were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The crystal size of silicon oxide and tin-doped silicon oxide increases from 1.1 to 9.3 nm by increasing the dopant concentration to overcome quantum confinement to enhance its absorption for sunlight. Moreover, the siloxane bond appeared in both silicon dioxide and tin-doped silica nanoparticles. The highest concentration (800 ppm) induces 80% and 100% mortality in sunlight, 68.8% and 100% mortality in artificial light, 10.4% and 17.6% mortality in darkness after 3 and 6 h, respectively. As a result, doped nanostructures show high potential larvicidal action in sunlight and may serve as effective alternatives for chemical pesticides.