Imidacloprid is an insecticide of the neonicotinoid family used to protect different types of crops such as wheat, beet or fruit trees. This substance is regularly detected in European surface waters. Nevertheless, the toxic effects on highly sensitive early life stages of fish at realistic environmental concentrations are not really known. The sturgeon taxa include several endangered species whose decline is multifactorial but for a part is linked to water pollution. The aim of this work was to assess the potential toxic effects of imidacloprid on Sterlet sturgeon (Acipenser ruthenus) when exposed during embryo-larval stages. To achieve this, exposure to environmental concentrations of imidacloprid (0.04µg/L to 4µg/L) was carried out from egg fertilization to resorption of the yolk sac under controlled laboratory conditions. In addition to survival, hatching success and growth (in size and weight) several toxicological endpoints were measured including, malformations, cardiac activity, swimming behavior, biomarkers (SOD, AchE, GST, TBARs, carbonylated proteins) and transcriptomics (gene expression). The results show that there was no mortality and no disruption of hatching success at any concentration. Growth criteria showed a significant difference in weight at the highest concentration, and a significant difference in head and eye size at the lowest concentration. No difference was observed for swimming behavior, but cardiac activity showed bradycardia at all concentrations compared with the control. Concerning gene expression, IMI-induced effects were found to be more pronounced at the lowest concentrations tested and were mainly associated with genes involved in energy metabolism (mitochondria) and nervous system development.
 

Ecotoxicology,embryos,imidacloprid,experimentation