Insecticidal activity of ZnO NPs synthesized by green method using pomegranate peels extract on stored product insects

Abstract

Green synthesis of nanomaterials is the most recent trend in nanotechnology since it takes into consideration the sustainable development and waste recycling, and it produces high value materials. Furthermore, the green synthesis excludes the use or production of toxic and hazardous chemicals to the environment. This work aimed to the green synthesis of zinc oxide nanoparticles (ZnO NPs) using pomegranate peels extract as a reducing and capping reagent instead of chemicals. Structural and morphological characterization of ZnO NPs was studied using X-ray diffraction (XRD), Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR), High-Resolution Transmission Electron Microscopy (HRTEM) and Energy Dispersive X-Ray Spectroscopy (EDX). In addition to the application of ZnO NPs as a green insecticide to control two destructive stored product insect pests; the rice weevil Sitophilus oryzae (L.) and the Angoumois grain moth Sitotroga cerealella (Olivier). The results of XRD, FTIR-ATR and EDX confirmed the formation of ZnO NPs. Also, XRD and HRTEM affirmed that the size of synthesized ZnO NPs have very small size around 4nm. The toxicity studies showed that green synthesized ZnO NPs exhibited a progressive increase in mortality of S. oryzae and S. cerealella adults subjected to treated wheat grains by increasing exposure intervals and concentration. A post toxic effect on progeny counts of S. oryzae and S. cerealella adults exposed to 3 concentrations of ZnO NPs was observed. Adherence of ZnO NPs to the body surface of treated adults was visualized using Scanning Electron Microscopy (SEM). Images showed strong uptake and massively attachment of nanoparticles through different parts of insect body. The present work suggests that eco-friendly synthesized ZnO NPs are promising green insecticide to control S. oryzae and S. cerealella stored product insect pests.