NEEA/SHS, São Carlos School of Engineering, University of São Paulo, Av. Trabalhador São Carlense, 400, 13.560-970, São Carlos, Brazil.
NEEA/SHS and PPG-SEA, São Carlos School of Engineering, University of São Paulo, Av. Trabalhador São Carlense, 400, 13.560-970, São Carlos, Brazil.
Environ Sci Pollut Res Int. 2023 May;30(23):63479-63490. doi: 10.1007/s11356-023-26847-z. Epub 2023 Apr 13.
In Brazil, among the pesticides widely applied simultaneously in sugarcane monocultures are the Regent® 800 WG insecticide (active ingredient (a.i.) fipronil) and the DMA® 806 BR herbicide (a.i. 2,4-D). Thus, this study aimed to investigate, through different endpoints, the effects of the fipronil and 2,4-D pesticides, isolated and as mixtures, on the cladoceran Daphnia similis. To do this, acute toxicity tests were carried out with the compounds acting in isolation and in mixture, where the survival of the organisms was evaluated, and chronic toxicity tests with the isolated compounds, where reproduction and maternal and neonatal body length were evaluated. In this study, the physiological endpoints of D. similis were also analyzed, through the analysis of feeding rates (filtration and ingestion) in exposure and post-exposure scenarios, in order to verify the cladoceran food recovery capacity. In addition, D. similis data were compared with other species when exposed to the studied pesticides, using species sensitivity distribution curves. Acute toxicity tests of the fipronil and 2,4-D showed an average EC-48 h of 66.68 μg a.i./L and 327.07 mg a.i./L, respectively. In both cases, D. similis showed lower sensitivity compared to other species. For the mixture test, the evaluation by the IA model (independent action) and deviation DR (dose ratio dependent) indicated the occurrence of mostly antagonistic effects. The chronic test with fipronil showed a decrease in the fecundity of the organism at a concentration of 16 μg a.i./L, a concentration already found in aquatic environments. For 2,4-D, no significant differences were observed for reproduction at the concentrations tested. Regarding the maternal body length, there were no significant changes when D. similis were exposed to both fipronil and 2,4-D, but these differences were observed in the body length of the neonates only for 2,4-D. There were no significant changes in the feeding rates of the organisms when exposed to both pesticides.
在巴西，在甘蔗单一种植园中广泛同时使用的农药有 Regent® 800 WG 杀虫剂（有效成分（a.i.）氟虫腈）和 DMA® 806 BR 除草剂（a.i. 2,4-D）。因此，本研究旨在通过不同的终点，研究氟虫腈和 2,4-D 农药单独和混合作用对枝角类动物 Daphnia similis 的影响。为此，进行了化合物单独和混合作用的急性毒性试验，评估了生物体的存活率，以及单独化合物的慢性毒性试验，评估了繁殖和母体及新生儿体长。在这项研究中，还通过在暴露和暴露后情景下分析摄食率（过滤和摄食），分析了 D. similis 的生理终点，以验证枝角类动物的食物恢复能力。此外，还使用物种敏感性分布曲线将 D. similis 暴露于研究农药时的数据与其他物种进行了比较。氟虫腈和 2,4-D 的急性毒性试验显示，平均 EC-48 h 分别为 66.68μg a.i./L 和 327.07mg a.i./L。在这两种情况下，D. similis 的敏感性均低于其他物种。对于混合物试验，IA 模型（独立作用）和偏差 DR（剂量比依赖性）的评估表明，主要发生拮抗作用。慢性氟虫腈试验表明，在 16μg a.i./L 的浓度下，生物体的繁殖力下降，而在水生环境中已经发现了这种浓度。对于 2,4-D，在测试的浓度下，繁殖没有显著差异。关于母体体长，当 D. similis 暴露于氟虫腈和 2,4-D 时，没有发生显著变化，但仅在 2,4-D 暴露时，幼体体长发生了变化。当暴露于这两种农药时，生物体的摄食率没有发生显著变化。
