Butterfly larvae as indicators to detect genotoxic effects of Particulate Matter (PM10)

Biodiversity is currently declining worldwide. This phenomenon has been determined as the sixth mass extinction. Several threats such as habitat loss and climate change have been identified. It is little known whether and how air pollution can act in addition to or in synergy with these threats, contributing to the decline of current species and/or local extinction. Few studies have analized the effects of particulate matter (PM), the main component of air pollution, on insects and no study has investigated its genotoxic effects through the Micronuclei assay. Butterflies play a key role in the environment, as herbivores during the larval stages, and as pollinators in adult stage. The aim of this study was to evaluate the genotoxic effects of PM10 from different sites along a gradient of urbanization, on a common species of Lepidopteran, Pieris brassicae. After exposure, the larvae cells were analysed through micronuclei assays. The results showed that all PM extracts induced significant DNA damage in the exposed caterpillars compared to the controls, and this increase in PM dose enhances the genotoxic effects. However, no significant difference was detected between sites with different levels of urbanization. In conclusion, PM induced genotoxic damage to butterfly larvae and it might could work with other toxic compounds, affecting the populations fitness, and possibly leading to local extinctions, especially for those species already threatened by other factors.