The aim of this study was to evaluate the acute effects of the pyrethroid cypermethrin (CYP) and the last generation pesticide spirotetramat (STM) on the prawn Macrobrachium borellii. Initially, the 96-h LC50 was determined in adult prawns. Then, prawns were exposed to sublethal concentrations of pesticides (5% and 20% of the 96-h LC50 values) for four days and hepatopancreas were dissected for biomarkers analyses. Total protein and uric acid content, glutathione S-transferase (GST) activity, levels of lipid peroxidation (LPO), and protein oxidation (PO) were evaluated. Additionally, the presence of histopathological changes, lipofuscins, and neutral lipids accumulation were analyzed. The 96-h LC50 values were 0.12 μg/L and 8.2 mg/L for CYP and STM, respectively. The total proteins and uric acid content were not significantly affected by the treatments (p > 0.05). STM significantly affected the GST activity only at the highest concentration (p < 0.001). However, LPO and OP levels were affected by the lowest concentrations of both pesticides (p < 0.003). CYP and STM caused dose-dependent histological damage as was indicated by the histopathological index. The accumulation of lipofuscins showed a dose-dependent response, while the neutral lipids were significantly accumulated in the prawns exposed to the lowest concentration of both pesticides (p < 0.001). The integrated biomarker index (IBRv2) results indicated that the histological parameters represented the most sensitive biomarkers in M. borellii exposed to CYP and STM. Besides, the pyrethroid showed the highest response at concentration ranges that could be present in its natural environments.
Keywords: Aquatic toxicology; Histopathology; LC(50); Oxidative stress; Pesticides; Prawn.
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