高崎 寛則

<jats:title>ABSTRACT</jats:title><jats:p>Pesticide contamination in freshwater ecosystems poses a significant threat to water quality and aquatic life, potentially disrupting entire food webs. Fluxametamide (FMT), a novel insecticide regarded as safe for nontarget species, has not been extensively studied in aquatic environments, raising concerns about its potential toxicity to organisms such as <jats:italic>Daphnia magna</jats:italic> (<jats:italic>D. magna</jats:italic>). This study investigates the acute toxicity of FMT, the potential of ultrafine bubbles (UFB), and the associated morphological alterations on <jats:italic>D. magna</jats:italic>. This result revealed that acute toxicity tests showed FMT is very toxic to <jats:italic>D. magna</jats:italic>, with LC<jats:sub>50</jats:sub> 24–48 h values of 0.051 and 0.013 µg/L, respectively. However, UFB has the potential to reduce the toxicity of FMT by twofold compared to control water in <jats:italic>D. magna</jats:italic>. Morphological analysis in the presence of UFB revealed carapace and body damage at high concentrations and prolonged exposure. In contrast, control water resulted in pesticide accumulation throughout the body, leading to more rapid tissue destruction even at lower concentrations and shorter exposure durations. In conclusion, UFB has the potential to alleviate the toxic effects of FMT by modifying its chemical structure, enhancing detoxification mechanisms, and minimizing its overall detrimental effect on <jats:italic>D. magna</jats:italic>. These findings represent an initial report on the effect of UFB on FMT toxicity in <jats:italic>D. magna</jats:italic>, providing essential theoretical foundations for the application of FMT in ecotoxicology.</jats:p>