*3.7. Mosquito Repellent Activity*

Data analysis showed that all tested concentrations exhibit more than 60% repellency against female *C. Pipiens* mosquitoes. However, the repellent activity of MgO-NPs was decreased with time increase (Figure 9C). The MgO-NPs concentrations of 10 mg/cm<sup>2</sup> , 5 mg/cm<sup>2</sup> , 2.5 mg/cm<sup>2</sup> , and DEET (as a positive control) showed repellency percentages of 95.16%, 90.34%, 87.45%, and 100%, respectively, for more than 60 min (Figure 9C).

Interestingly, the repellency percentages between 10 mg/cm<sup>2</sup> and the positive control do not show any difference after 240 min (94.1% and 94.2%) and 480 min (87.3% and 87.5%). After maximum time (8 h), the repellence percentages were 78.6%, 67.1%, and 46. 78% for MgO-NPs concentration of 5 mg/cm<sup>2</sup> , 2.5 mg/cm<sup>2</sup> , and 1.0 mg/cm<sup>2</sup> , respectively, as compared with DEET (87.6%). Based on the obtained data, the MgO-NPs have repellence activity at high concentrations as compared to commercial substances (EDDT). The TiO2- NPs exhibit repellence activity against *Aedes aegypti* with a value of 80.43% at 100 ppm [101]. The present study provides an eco-friendly, cost-effective, and simple approach to control the spread of *C. Pipiens* populations, as well as new repellent agents that can be used instead of commercial compounds.
