Facile Synthesis of Copper Oxide Micro/-Nanostructures with Prospective Insecticidal Activity on Fall Armyworm (Spodoptera frugiperda)

Nanotechnology provides innovative agrochemicals for improving crop production and quality by fabricating nanomaterial-based agrochemicals (i.e., nano-pesticides). The application of nano-pesticides in modern agriculture offers efficient programs for pest management. Herein, Copper oxide with flower-like structure (CuO-FLS) and rod-like structure (CuO-RLS) were synthesized via simple wet chemical methods and applied against Fall Armyworm (Spodoptera Frugiperda). The synthesized copper oxide micro/-nanostructures were characterized by wide-angle powder X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), N2 adsorption/desorption isotherms to determine surface properties, and Field-emission scanning electron microscopy (FE-SEM) to investigate the morphology. XRD and FT-IR analysis confirms the formation of highly crystalline materials of the monoclinic Tenorite CuO. Surface measurements showed that CuO-NPs revealed type IV isotherm with specific surface areas of SBET = 40.54 and 52.63 m2/g for CuO-FLS and CuO-RLS, respectively. FE-SEM illustrates the formation of aggregated needles with an average diameter of 100-200 nm arranged in a hierarchical flower-like structure with an average size of 1.0 µm (CuO-FLS) and rod-like microstructure with an average size of 0.5-1.0 µm (CuO-RLS). The physicochemical properties of the synthesized CuO have a role in their insecticidal activity. The insecticidal activity for both is comparable without signifying differences between mortalities. CuO-FLS has a higher insecticidal effect (LC50=118.68 ppm) than CuO-RLS (LC50 = 134.95 ppm).