An in vivo assessment revealed multiple toxic effects of brake dust on the urban mosquito Aedes albopictus

Brake dust is a major component of particulate matter (PM) and enriched in potentially toxic elements (PTEs), posing a significant threat to both the environment and health especially in densely populated areas. In this context, an in vivo approach is essential to understand its potential negative effects. Here, we investigated the toxicity of brake dust on Aedes albopictus, a common mosquito species in urban environments. We exposed larvae to increasing concentrations of brake dust in the water (10-500 mg L^-1) to evaluate: (i) effects on developmental, behavioural and morphological traits; (ii) element bioaccumulation; (iii) oxidative stress. We found a significant reduction in adult emergence rate, delayed larval growth, and morphological changes in male wing shape. At high brake dust concentrations, an increase in cannibalistic interactions among larvae was also observed. Furthermore, we demonstrated that larvae bioaccumulate elements from brake dust in different ways, with Cu, La, Ce, and Ba which were progressively bioaccumulated as brake dust concentration increased, while most other PTEs showed bioaccumulation up to 50 mg L^-1, followed by a decrease at higher concentrations. The overexpression of superoxide dismutase (SOD) and catalase genes at concentrations above 50 mg L^-1 indicated induction of oxidative stress response. We conclude that the toxic effects of brake dust on Ae. albopictus occurred at multiple levels, with important biological and ecological relevance. Moreover, our findings identify Ae. albopictus as a valuable model for in vivo studies on PM toxicity.