<p>Generation and use of titanium dioxide nanoparticles (TiO₂ NPs) is in abundance all over the world for various commercial applications. Due to their large production, broad applications, and unregulated disposal, these nanoparticles (NPs) are unavoidably released into the environment and are posing a threat to biodiversity and human health. In order to assess their risk, the present study regarding the impact of the nanoparticles on germ cells and embryo development in mosquito <i>Culex quinquefasciatus</i> has been taken up. Early fourth instar larvae were exposed to the selected dose 50&#xa0;µg/ml (&lt; LD₂₀) for 24-h treatment. Sperm samples collected from seminal vesicles of treated and control male mosquitoes were analyzed for sperm count alterations and sperm head abnormalities caused by these nanoparticles. These nanoparticles are reported toxic to germ cells as a statistically significant decline in sperm count and increase in sperm head abnormalities (<i>p</i> &lt; 0.05) in treated mosquitoes over the controls were observed. Moreover, these nanoparticles were found to impact egg laying potential and their hatching frequency due to the death of developing embryos within the eggs obtained from genetic crosses of treated virgin females with normal male mosquitoes. From these observations, it can be concluded that these nanoparticles possess reproductive and embryo toxicity which may impact the survival of the species in the long run and may be a contributory factor in the extinction of some non-target species. The present study is an important step to sensitize the concerned people for developing strategies for the safe use and disposal of these nanoparticles and prevent the vulnerable species from the danger of extinction from the planet.</p>