Solanum incanum-mediated green synthesis and characterization of silver oxide, zinc oxide, and copper oxide nanoparticles for the control of maize weevils (Sitophilus zeamais) and postharvest microbial contamination

Environmentally friendly green synthesis of metal oxide nanoparticles provides the best ways of protection for post-harvest pest and microbial management. This study reports the synthesis of silver oxide (Ag2O), zinc oxide (ZnO), and copper oxide (CuO) nanoparticles using the aqueous root extract of Solanum incanum (SI) as a reducing and capping agent. The synthesized nanoparticles were characterized by UV-Vis spectroscopy (UV-Vis), Fourier-Transform Infrared Spectroscopy (FTIR), X-Ray diffraction (XRD), and Scanning electron microscopy (SEM) to determine optical features, functional groups, crystalline phases, and morphology, respectively.Bioassay against maize weevil and pathogenic bacteria was evaluated and has shown promising insecticidal activity against maize weevils and the pathogens. The 100% mortality is observed for all the biosynthesized nanoparticles and plant extract in a 16-day treatment against the maize weevil (Sitophilus zeamais). Among the three metal-oxide nanoparticles test result, the highest efficacy was observed for ZnO-NPs-SI against Bacillus cereus (28 mm) followed by CuO-NPs-SI against Escherichia coli (25 mm) and ZnO-NPs-SI against Staphylococcus aureus (24 mm).These results show that SI-mediated Ag2O, ZnO, and CuO NPs have promising activity in both controlling S. zeamais and reducing bacterial contamination. This makes them good candidates for green postharvest protection of maize.