Utilizing spiders for biomonitoring air pollution from road traffic: a novel approach and preliminary findings

Polycyclic aromatic hydrocarbons (PAHs) are air pollutants generated mainly by fuel combustion, industry, and other anthropogenic sources. The level of these pollutants can be assessed by employing biomonitors, a cost-effective and less contaminating alternative than conventional methods. In the present study, we aimed to investigate whether spiders inhabiting areas around a major city like Córdoba, Argentina, adsorb and retain PAHs in their exoskeletons. Additionally, we aimed to determine if spiders' life traits influence their capacity to accumulate PAHs and explore potential relationships between PAH levels and the types of roads where they were collected. Specimens of a funnel-shaped web spider (Aglaoctenus lagotis) and an orb-weaver (Metepeira spp.) were collected from roadsides. Roads were classified into four categories based on their traffic intensity. Using high-performance liquid chromatography (HPLC), we identified 15 different PAHs. Both species exhibited varying concentrations of PAHs, although Metepeira spp. showed 15-18 times higher PAH levels compared to A. lagotis. Moreover, A. lagotis individuals living alongside highways accumulated up to six times more PAHs compared to those along other road types. These findings suggest that spiders' life traits may influence pollutant concentrations. Our study demonstrates that spiders near roads are exposed to and accumulate PAHs on their exoskeletons, likely sourced from petrogenic vehicular emissions, highlighting their value as biomonitors and emphasizing the need for mitigation measures to address air pollutants emitted from mobile sources.