Neonicotinoid mixture alters trophic interactions in a freshwater aquatic invertebrate community

• Published in: The Science of the total environment Vol. 897; p. 165419
• Main Authors: Duchet, Claire, Hou, Fan, Sinclair, Cailin A., Tian, Zhenyu, Kraft, Alyssa, Kolar, Vojtech, Kolodziej, Edward P., McIntyre, Jenifer K., Stark, John D.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.11.2023
• Subjects: Aquatic invertebrates; Community-levels; Mixture; Neonicotinoid insecticides; Trophic interactions; Aquatic invertebrates; Community-levels; Neonicotinoid insecticides; Mixture; Trophic interactions
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.165419

Neonicotinoids are increasingly and widely used systemic insecticides in agriculture, residential applications, and elsewhere. These pesticides can sometimes occur in small water bodies in exceptionally high concentrations, leading to downstream non-target aquatic toxicity. Although insects appear to be the most sensitive group to neonicotinoids, other aquatic invertebrates may also be affected. Most existing studies focus on single-insecticide exposure and very little is known concerning the impact of neonicotinoid mixtures on aquatic invertebrates at the community level. To address this data gap and explore community-level effects, we performed an outdoor mesocosm experiment that tested the effect of a mixture of three common neonicotinoids (formulated imidacloprid, clothianidin and thiamethoxam) on an aquatic invertebrate community. Exposure to the neonicotinoid mixture induced a top-down cascading effect on insect predators and zooplankton, ultimately increasing phytoplankton. Our results highlight complexities of mixture toxicity occurring in the environment that may be underestimated with traditional mono-specific toxicological approaches. The neonicotinoid mixture induced a top-down cascading effect on the aquatic invertebrates, leading to an increase of phytoplankton. [Display omitted] •A mixture of three common neonicotinoids was evaluated on a freshwater invertebrate community, in outdoor mesocosms, at environmentally relevant concentrations.•The mixture induced a top-down cascading effect on insect predators and zooplankton, leading to an increase of phytoplankton.•Lab-derived models with single compounds may underestimate the effects of neonicotinoid mixtures in the environment.•Semi-field and field-based studies are crucial to better characterize the toxic responses of neonicotinoid mixtures.