Blatella germanica is a major domiciliary pest associated with public health. Synthetic insecticides have hazardous effects on humans and the environment. This study aimed to evaluate the efficiency of three Nano formulations against the German cockroach. Silicon dioxide (SiO2), Zinc oxide (ZnO) and Copper oxide (CuO) nanoparticles (NPs) were synthesized and screened for insecticidal activity against adults of the German cockroach by contact and feeding methods. The synthesized nanoparticles were attained in a powder form and characterized using UV-Vis spectrophotometer, High-Resolution Transmission Electron Microscopy (HRTEM), Dynamic light scattering (DLS) and zeta potential. The size range of the prepared NPS was 5.16-14.72 nm for SiO2, 26.50-52.56 nm for ZnO-NPs and 10.04-39.7 nm for CuO-NPs. Results of UV-Vis spectroscopy, HRTEM, DLS and Zeta potential confirmed the successful formation of nanoparticles. Results clearly showed that the SiO2-NPs had strong insecticidal activity against adults of German cockroaches with LC50 values of 10.36 mg by contact and 4.91 mg by feeding methods. While the LC50 values of ZnO- and CuO-NPs were 13.02 & 17.35 mg by contact and 5.94 & 6.19 mg, respectively by feeding methods. On the other hand, the crude powder of the three metals induced non-significant toxic effects. The LC50 values were 87.49, 179.27 and 233.24 mg by contact, and 9.31, 17.99 and 19.21 mg by feeding for Silica, Zinc and Copper powders, respectively after 7 days of treatment. The stability of the prepared NPs was studied after 4 months of storage under laboratory conditions. SiO2-NPs were the most stable, followed by ZnO-NPs and CuO-NPs. The efficacy and stability of the prepared NPs made these products suitable candidates for controlling the German cockroach. |
