Arsenic exposure in insects from green spaces near a former copper smelter

Urban green spaces play a crucial role in protecting insect biodiversity against habitat loss. However, chemical pollution poses a potential threat to these ecosystems, making ecological risk assessment essential. In the city of San Luis Potosí, a former copper smelter operated for several decades, releasing arsenic into the environment. Despite this, its ecological impact has received no attention, which is important given the presence of nearby green spaces that provide habitat for urban insects. This study assessed arsenic levels in soil, plants, and insects near this former copper smelter to determine whether this pollutant poses risks to local insects. The study sites included green spaces near the smelter (smelter-impacted zone) and reference green spaces (reference zone), both ubicated within the same city. The study sites harbor more than 50 insect families with different ecological roles. Arsenic levels in soil, plants, and insects in the smelter-impacted zone were 4, 2, and 20 times higher compared to the reference zone, respectively. The analysis of exposure routes indicates that soil is a direct route for plants and insects, plants transfer the arsenic to several herbivores, decomposers reincorporate arsenic into the trophic chain, and predators are also exposed. Moreover, Cotinis mutabilis (Coleoptera: Scarabaeidae: Cetoniinae) was identified as a bioindicator of arsenic pollution, showing a positive correlation between its tissue concentrations and arsenic levels in soil. In conclusion, this study demonstrates that arsenic pollution threatens insects in the smelter-impacted zone, highlighting the need for further research to assess the potential ecological risks.