Intergenerational effects of coal dust on Tribolium castaneum, Herbst.

Coal dust is a primary air contaminant from coal mining operations that produces harmful health effects. However, it is unclear to what extent its detrimental properties would impact future generations, and whether alterations in the progenies might be concentration-dependent. The aim of this study was to determine the intergenerational effects of chronic exposure to coal dust on the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), at three life stages. Groups of fifty adult insects were exposed during 30 days at different concentrations of coal dust mixed with ground oats as food substrate (0, 0.25, 0.5, 1.0 and 2.0% weight/weight), both with a particle size <38 μm. The LC for F0 insects was 1.07%, whereas for larvae and adults from F1, values were 0.53 and 0.89%, respectively. Pathological findings assessed at F1 revealed a coal dust concentration-dependent frequency of several morphological abnormalities, including larvae without antenna or extremities, lack of T1, T2, T3 legs, loss of urogomphi, and the presence of abnormal protuberances. It was found that a considerable number of F1 larvae derived from parental beetles did not achieve a complete conversion into the next growth stage. Pupae with undeveloped eyes and adults with malformed elytra, as well as necrosis, were recurrently observed at high concentrations. Finally, adults exposed to 1% coal dust overexpressed genes related to oxidative stress (nuclear factor erythroid 2-related factor 2, Nrf2) and synaptic transmission (GABA-gated ion channel, Grd). In short, coal dust particles induced intergenerational effects on T. castaneum, highlighting the need to further study the impact of this airborne pollutant on wildlife and human populations.