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, HighResolution 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.
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