Effects of imidacloprid and a neonicotinoid mixture on aquatic invertebrate communities under Mediterranean conditions

• Published in: Aquatic toxicology Vol. 204; pp. 130 - 143
• Main Authors: Rico, Andreu, Arenas-Sánchez, Alba, Pasqualini, Julia, García-Astillero, Ariadna, Cherta, Laura, Nozal, Leonor, Vighi, Marco
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.11.2018
• Subjects: Invertebrates; Mediterranean climate; Mixture toxicity; Model ecosystems; ms-PAF; Neonicotinoids; Neonicotinoids; ms-PAF; Invertebrates; Mixture toxicity; Model ecosystems; Mediterranean climate
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2018.09.004

•Effects of imidacloprid and a neonicotinoid mixture assessed in freshwater mesocosms.•NOECs <0.2 μg/L for Cyclopoida, Cloeon dipterum and Chironomini.•Threshold concentrations derived for Mediterranean aquatic ecosystems.•The concentration addition model can be used to assess the risks of neonicotinoid mixtures.•The ms-PAF approach accurately predicts effects under semi-field conditions. Neonicotinoid insecticides are considered contaminants of concern due to their high toxicity potential to non-target terrestrial and aquatic organisms. In this study we evaluated the sensitivity of aquatic invertebrates to a single application of imidacloprid and an equimolar mixture of five neonicotinoids (imidacloprid, acetamiprid, thiacloprid, thiamethoxam, clothianidin) using mesocosms under Mediterranean conditions. Cyclopoida, Cloeon dipterum and Chironomini showed the highest sensitivity to neonicotinoids, with calculated NOECs below 0.2 μg/L. The sensitivity of these taxa was found to be higher than that reported in previous studies performed under less warm conditions, proving the high influence of temperature on neonicotinoid toxicity. The short-term responses of the zooplankton and the macroinvertebrate communities to similar imidacloprid and neonicotinoid mixture concentrations were very similar, suggesting that the concentration addition model can be used as a plausible hyphotesis to assess neonicotinoid mixture effects in aquatic ecosystems. Long-term mixture toxicity assessments, however, should consider the fate of the evaluated substances in the environment of concern. As part of this study, we also demonstrated that Species Sensitivity Distributions constructed with chronic laboratory toxicity data and calculated (multi-substance) Potentially Affected Fractions provide an accurate estimation to asssess the ecotoxicologial risks of imidacloprid and neonicotinoid mixtures to aquatic invertebrate species assemblages.