The widespread applications of ZnO NPs in the different areas of science, technology, medicine, agriculture, and commercial products have led to increased chances of their release into the environment. This created a growing public concern about the toxicological and environmental effects of the nanoparticles. The impact of these NPs on the genetic materials of living organisms is documented in some cultured cells and plants, but there are only a few studies regarding this aspect in animals. In view of this, the present work regarding the assessment of the genotoxicity of zinc oxide nanoparticles using the mosquito Culex quinquefaciatus has been taken up. Statistically significant chromosomal aberrations over the control are recorded after the exposure of the fourth instar larvae to a dose of less than LD₂₀ for 24 h. In order to select this dose, LD₂₀ of ZnO NPs for the mosquito is determined by Probit analysis. Lacto-aceto-orcein stained chromosomal preparations are made from gonads of adult treated and control mosquitoes. Both structural aberrations, such as chromosomal breaks, fragments, translocations, and terminal fusions, resulting in the formation of rings and clumped chromosomes, and numerical ones, including hypo- and hyper-aneuploidy at metaphases, bridges, and laggards at the anaphase stage are observed. The percentage frequency of abnormalities in the shape of sperm heads is also found to be statistically significant over the controls. Besides this, zinc oxide nanoparticles are also found to affect the reproductive potential and embryo development as egg rafts obtained from the genetic crosses of ZnO nanoparticle-treated virgin females and normal males are small in size with a far smaller number of eggs per raft. The percentage frequencies of dominant lethal mutations indicated by the frequency of unhatched eggs are also statistically significant (p < 0.05) over the control. The induction of abnormalities in all of the three short-term assays studied during the present piece of work indicates the genotoxic potential of ZnO NPs, which cannot be labeled absolutely safe, and this study pinpoints the need to develop strategies for the protection of the environment and living organisms thriving in it.

A polyphagous nocturnal pest Spodoptera litura (Fabr.) commonly called armyworm, infests about 150 plant species across 44 families worldwide, with nearly 60 plant species affected just in India. The majority of leaf tissues are consumed by the larvae and only the stem and side shoots will remain in the field. They entirely consume the interior content by boring into them, causing squares and young bolls to shed. This insect can badly affect crops and has a wide range of potential hosts, which can lead to financial losses for farmers and food shortages for consumers. The worldwide distribution of S. litura as a pest results in significant impact on productivity of many crops. They have the capability to invade new places as a wide-ranging species. Armyworm frequently reappears in India every year and causes evident destruction. Different records on the insect population outbreak have been reported from many countries all around the world. The larvae of insect pests enter the fruits and even contaminate it and this causes yield and economic losses. The low temperatures of winter season are the limiting factors that affect species. It migrates mainly to breed during the summer season but is unable to survive in winters. S. litura acquired resistance to several synthetic insecticides, which led to pest outbreaks that were irregular and caused failure of different crops. The resistance and cross-resistance of this pest against insecticide toxin make it more difficult to reduce its population below threshold level. Understanding the mechanisms of resistance is crucial for developing effective resistance management strategies that can restrict or halt the spread of resistance in these pest populations.

Titanium dioxide (TiO₂) nanoparticles are being extensively used in a wide range of industrial applications for producing a variety of different consumer products, including medicines and even food items. The consumption of these products is increasing at an alarming rate, and this results in the release of these nanoparticles in the environment, causing a threat to organisms thriving in aquatic as well as terrestrial ecosystems. That is why screening such materials for their genotoxic effects, if any, becomes essential. A toxicity assay was performed to determine the LD₂₀ of these nanoparticles for the mosquito Culex quinquefaciatus by Probit analysis. Early fourth instar larvae were exposed to the selected dose of 50 µg/mL, which is <LD₂₀ value, for 24 h treatment. Chromosomal slides were prepared from lacto-aceto-orcein-stained gonads of adult mosquitoes developed from treated and control larvae. These nanoparticles were reported cytotoxic as a statistically significant decline in mitotic index in treated mosquitoes than controls were observed. The nanoparticles were also found to induce various structural and numerical chromosomal aberrations in the treated lot. In the end, it can be concluded that these nanoparticles do have a genotoxic effect. The present study provides a caution against further use of these nanoparticles. There must be the development of strategies for the safe, sustainable use as well as proper disposal of these nanoparticles so as to protect both biotic and non-biotic components of the environment.