Abstract：
The magnitude of copepods\' responses to pesticides, individually and in mixture, is little understood. The aims of this study were to evaluate: (i) the effects of the pesticides fipronil and 2,4-D, individually and in mixture, on the freshwater copepod Notodiaptomus iheringi; and (ii) the survival and the feeding rate of copepods after the exposure. Acute toxicity tests using the commercial formulations of fipronil and 2,4-D, individually and in mixture, were performed. The LC10-48h, LC20-48h, and LC50-48h of fipronil to N. iheringi were 2.38 ± 0.48, 3.08 ± 1.14, and 4.97 ± 3.30 μg L-1, respectively. For 2,4-D the LC10-48h, LC20-48h, and LC50-48h were 371.18 ± 29.20, 406.93 ± 53.77, and 478.24 ± 107.77 mg L-1, respectively. Morphological damages on the copepods exposed to pesticides were observed at all concentrations. Fungal filaments covering dead organisms were presented at the treatment highest concentration (R5:7.43 ± 2.78 μg L-1 fipronil). The mixture of the pesticides presented synergistic effects on the mortality of N. iheringi. Post-exposure tests showed no difference between the treatments and the control on the mortality and on the feeding rate for 4 h. However, since delayed toxicity of pesticides can occur, longer post-exposure tests using N. iheringi should be tested. N. iheringi is a key species in the aquatic Brazilian ecosystem and showed sensitivity to fipronil and 2,4-D; thus, more studies with this species assessing other responses are recommended.
摘要：
co足类对杀虫剂的反应程度，单独和混合，很少被理解。这项研究的目的是评估：（i）农药氟虫腈和2,4-D的作用，单独和混合，在淡水co足类Notodiaptomusiheringi上；（ii）暴露后co足类的存活率和摄食率。使用氟虫腈和2,4-D的商业制剂进行急性毒性测试，单独和混合，被执行了。LC10-48h,LC20-48h,氟虫腈对黑耳菌的LC50-48h分别为2.38±0.48、3.08±1.14和4.97±3.30μgL-1。对于2,4-DLC10-48h，LC20-48h,LC50-48h分别为371.18±29.20、406.93±53.77和478.24±107.77mgL-1。在所有浓度下都观察到了暴露于农药的co足类的形态损害。以最高的处理浓度（R5：7.43±2.78μgL-1氟虫腈）呈现覆盖死亡生物的真菌丝。农药混合物对黑猪的死亡率具有协同作用。暴露后试验表明，治疗和对照组在4小时的死亡率和摄食率上没有差异。由于农药的延迟毒性可能发生，应使用N.iheringi进行更长的暴露后测试。N.iheringi是巴西水生生态系统中的关键物种，对氟虫腈和2,4-D表现出敏感性；因此，建议对该物种进行更多研究，以评估其他反应。
