This study aimed to assess the toxicity of the anthelmintic drug praziquantel in the early life stages of grass carp (Ctenopharyngodon idella). The toxicity was evaluated based on mortality, early ontogeny development, growth, oxidative stress biomarkers, antioxidant enzymes and histopathology. Praziquantel at all tested concentrations (1, 2, 4 and 6 mg/l) showed no significant adverse effects on the hatching of grass carp. Concentrations of 2, 4 and 6 mg/l praziquantel caused significantly (P < 0.01) higher mortality and slower growth compared with controls. Praziquantel at concentrations (4 and 6 mg/l) showed a significant (P < 0.01) delay of early ontogeny of grass carp. Concentration of 2 mg/l praziquantel caused significantly (P < 0.01) higher GST activity than controls. Among the groups, no histological changes were detected in tissues. For the early life of grass carp, praziquantel is safe at concentrations ≤1 mg/l.

• Keywords
• antioxidant biomarkers, antiparasitic drug, carp, fish, histopathology,
• Publication type
• Journal Article MeSH

Neonicotinoids are one of the newest groups of systemic pesticides, effective on a wide range of invertebrate pests. The success of neonicotinoids can be assessed according to the amount used, for example, in the Czech Republic, which now accounts for 1/3 of the insecticide market. The European Union (EU) has a relatively interesting attitude towards neonicotinoids. Three neonicotinoid substances (imidacloprid, clothianidin and thiamethoxam) were severely restricted in 2013. In 2019, imidacloprid and clothianidin were banned, while thiamethoxam and thiacloprid were banned in 2020. In 2022, another substance, sulfoxaflor, was banned. Therefore, only two neonicotinoid substances (acetamiprid and flupyradifurone) are approved for outdoor use in the EU. Neonicotinoids enter aquatic ecosystems in many ways. In European rivers, neonicotinoids usually occur in nanograms per litre. Due to the low toxicity of neonicotinoids to standard test species, they were not expected to significantly impact the aquatic ecosystem until later studies showed that aquatic invertebrates, especially insects, are much more sensitive to neonicotinoids. In addition to the lethal effects, many studies point to sublethal impacts - reduced reproductive capacity, initiation of downstream drift of organisms, reduced ability to eat, or a change in feeding strategies. Neonicotinoids can affect individuals, populations, and entire ecosystems.

• Keywords
• acetamiprid, aquatic ecosystems, flupyradifurone, nicotinic acetylcholine receptors agonists, thiacloprid, toxicity,
• Publication type
• Journal Article MeSH
• Review MeSH

Degradation products of herbicides, alone and in combination, may affect non-target aquatic organisms via leaching or runoff from the soil. The effects of 50-day exposure of primary metabolites of chloroacetamide herbicide, acetochlor ESA (AE; 4 µg/L), and glyphosate, aminomethylphosphonic acid (AMPA; 4 µg/L), and their combination (AMPA + AE; 4 + 4 µg/L) on mortality, growth, oxidative stress, antioxidant response, behaviour, and gill histology of early life stages of marbled crayfish (Procambarus virginalis) were investigated. While no treatment effects were observed on cumulative mortality or early ontogeny, growth was significantly lower in all exposed groups compared with the control group. Significant superoxide dismutase activity was observed in exposure groups, and significantly higher glutathione S-transferase activity only in the AMPA + AE group. The gill epithelium in AMPA + AE-exposed crayfish showed swelling as well as numerous unidentified fragments in interlamellar space. Velocity and distance moved in crayfish exposed to metabolites did not differ from controls, but increased activity was observed in the AMPA and AE groups. The study reveals the potential risks of glyphosate and acetochlor herbicide usage through their primary metabolites in the early life stages of marbled crayfish.

• Keywords
• behaviour, crayfish, herbicide, metabolite, ontogeny, toxicity,
• Publication type
• Journal Article MeSH