Radiation-Assisted Green Synthesis and Characterization of Selenium Nanoparticles, and Larvicidal Effects on Culex pipiens complex

Many environmental hazards are due to chemical insecticides and enhance mosquito species' resistance. This problem is solved by using safer nanocides that reduce environmental pollution among integrated pest management (IPM) programs. Selenium nanoparticles (SeNPs) were green synthesized using Cupressus sempervirens, microwave (MW), and gamma irradiation (G) methods. Synthesized-SeNPs were characterized using UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Dynamic light scattering (DLS), X-ray diffraction (XRD), Zeta potential analysis, and Transmission electron microscopy (TEM). Characterization revealed stable spherical particles with size 11-55 nm for SeNPs-MW (20 min) and 21-75 nm for SeNPs-G (40 KGy). Gamma and microwave irradiations play significant roles in increasing SeNPs yield and decreasing their size. The accumulative mortality of Culex pipiens complex larvae for SeNPs-MW and SeNPs-G at LC50 were 28.25 mg/L and 31.28 mg/L. The accumulated selenium concentration was increased in SeNPs-G treated larvae and measured with inductively coupled plasma mass spectrometry (ICP-MS). Ultrastructural study of the integument using TEM and light microscopy examination of midgut showed clear penetration and accumulation of SeNPs in exoskeleton and several deteriorations in epithelial cells. The results highlighted the important role of gamma and microwave irradiation with plant extract in synthesis and stabilization of SeNPs and their insecticidal efficacy against mosquitoes.