The insecticide fipronil and the herbicide 2,4-D are the most applied pesticides in sugarcane crops leading to aquatic contamination. The whole-body bioconcentration of fipronil and 2,4-D, single and in mixture, was evaluated in Danio rerio after 96-h exposure. The activities of catalase (CAT) and glutathione S-transferase(GST) in whole body and in the gills and the acetylcholinesterase (AChE) in muscle were determined. The gill histopathology and the morphology of the pavement (PVC) and the mitochondria-rich(MRC) cells at gill surface were analyzed. Bioconcentration occurred after exposure to fipronil (2.69 L kg⁻¹) and 2,4-D (1.73 L kg⁻¹) single and in mixture of fipronil (3.10 L kg⁻¹) and 2,4-D (1.27 L kg⁻¹). Whole-body CAT activity was unchanged, and its activity decreased in the gills after exposure to fipronil and increased after exposure to 2,4-D and mixture. GST and AChE increased after single exposure to each pesticide and mixture of both. Fish exposed to mixture increased the MRC fractional area (MRCFA) which suggested possible ionic regulation disturbance and reduced the microridge of the PVC surface. Synergistic interactions occurred in the CAT activity and MRCFA after exposure to mixture of pesticides. The results indicate that the recommended application dose of fipronil and 2,4-D, single or in mixture, for sugarcane crops affects this fish species altering its homeostasis.

杀虫剂氟虫腈和除草剂 2,4-D 是甘蔗作物中使用最多的杀虫剂，会导致水生污染。暴露 96 小时后，在斑马鱼中评估了氟虫腈和 2,4-D，单一和混合的全身生物浓度。测定了全身和鳃中过氧化氢酶（CAT）和谷胱甘肽S-转移酶（GST）的活性以及肌肉中的乙酰胆碱酯酶（AChE）的活性。分析了鳃组织病理学和鳃表面铺层（PVC）和富含线粒体（MRC）细胞的形态。在氟虫腈 (2.69 L kg ^-1 ) 和 2,4-D (1.73 L kg ^-1 ) 单一和氟虫腈 (3.10 L kg ^-1 ) 和 2,4-D (1.27 L kg ^{- 1}）。全身CAT活性没有变化，在鳃中其活性在暴露于氟虫腈后降低，而在暴露于2,4-D和混合物后增加。GST 和 AChE 在单次接触每种农药和两者的混合物后增加。暴露于混合物中的鱼增加了 MRC 分数面积 (MRCFA)，这表明可能存在离子调节干扰并减少了 PVC 表面的微脊。暴露于农药混合物后，CAT 活性和 MRCFA 发生协同相互作用。结果表明，甘蔗作物推荐的氟虫腈和 2,4-D 单独或混合施用剂量会影响这种鱼类，从而改变其体内平衡。