Nanotechnology takes a significant position to control pests. Silicon dioxide nanoparticles (SiO2-NPs) is considered one of the best alternates to chemical pesticides for plant crop protection from harmful arthropods such as phytophagous mites, Tetranychus urticae. Therefore, this study aims to evaluate the effect of (SiO2-NPs) to control T. urticae. Under greenhouse conditions, the results revealed, in larval stage, high mortality percentage (99.05±0.83%) followed by eggs (98.74±1.22%). Also,

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... ymph stage recorded high mortality (94.66±1.81%) at high concentration 1500 ppm. While the adult females of T. urticae recorded mortality 91.92±1.02% after 72h. Eventually, the immature stages of T. urticae were susceptible to (SiO2-NPs). Meanwhile, at laboratory evaluation on immature stages of T. urticae which resulted from live treated females during 96h showed a sharp decrease in average numbers of eggs through 96h, at 1000 and 1500 ppm. No numbers of the larval stage were recorded at 1500 ppm. No numbers of nymph stage were recorded at all concentrations and periods. Moreover, activity of AChE was significantly inhibited at 1500 ppm, while activity of glutathione-Stransferase was significantly increased after 72 h. Finally, (SiO2-NPs) are effective against immature stages of T. urticae under greenhouse and laboratory conditions.