Simple SummaryIndustrial activities significantly damage the surrounding environment due to the release of contaminants of various types. Therefore, the search for parameters that can provide information on the quality of the environment is of great relevance. In this research, for the first time, specimens belonging toOpsius heydeni, an insect living onTamarixplants, were sampled and analyzed at two Sicilian sites (the polluted industrial site Priolo Gargallo and the control site Oasi del Simeto) to study the effect of pollution on wildlife organisms. Using molecular biology techniques, it has been seen that environmental pollutants can modify the mitochondrial DNA in these specimens; in particular, a decrease in the number of DNA molecules was observed in the specimens sampled at Priolo Gargallo. In conclusion, these results highlight how the studied species can be useful to monitor the effects of pollutants on biota.AbstractMitochondrial DNA easily undergoes alterations due to exposure to stress factors. In particular, mitochondrial DNA copy number (mtDNAcn) variation can be used as a biomarker of the effect of exposure to various environmental contaminants. In this study, a molecular investigation based on the evaluation of mtDNAcn variation was applied for the first time to individuals belonging to the speciesOpsius heydeni. A total of 20 samples were collected from two sites in eastern Sicily: Priolo Gargallo, a site with a strong anthropic impact, and the Simeto river Oasis, a control site. Specimens identified based on morphological traits were used to obtainCOIgene sequences from this species that were not previously available in GenBank. After processing, the relative mtDNAcn was evaluated using real-time PCR of a portion of theCOIand18Sgenes. A decrease in the mtDNAcn in the specimens from the polluted site was observed. These results highlight how environmental contaminants can alter the mitochondrial genome and howOpsius heydenican be considered a potential bioindicator species of environmental quality.