Pesticides occur in the environment as mixtures, yet the joint toxicity of pesticide mixtures remains largely under-explored and is usually overlooked in ecological risk assessment. In the current study, joint toxicity of a neonicotinoid insecticide (imidacloprid, IMI) and a strobilurin fungicide (azoxystrobin, AZO) was investigated with Chironomus dilutus over a wide range of concentrations and at different effect levels (organism, cell, and gene levels). The two pesticides, both individually and in combination, were found to induce oxidative stress and cause lethality in C. dilutus. Median lethal concentrations for IMI and AZO were 3.98 ± 1.17 and 52.9 ± 1.1 μg/L, respectively. Mixtures of the two pesticides presented synergetic effects at environmentally relevant concentrations whilst antagonistic effects at high concentrations, showing concentration-dependent joint toxicity. Investigation on the expressions of 12 genes (cyt b, coi, cox1, cyp4, cyp12m1, cyp9au1, cyp6fv1, cyp315, gst, Zn/Cu-sod, Mn-sod, and cat) revealed that the two pesticides impaired mitochondrial respiration, detoxification, and antioxidant system of C. dilutus, and the joint effects of the two pesticides were likely due to an interplay between their respective influences on these physiological processes. Collectively, the synergistic effects of the two pesticides at environmentally relevant concentrations highlight the importance to incorporate combined toxicity studies into ecological risk assessment of pesticides.

农药以混合物形式存在于环境中，但农药混合物的联合毒性仍未得到充分开发，通常在生态风险评估中被忽略。在当前的研究中，使用稀释性Chironomus dilutus研究了新烟碱类杀虫剂（吡虫啉，IMI）和嗜球果伞素类杀真菌剂（叠氮霉素，AZO）的联合毒性，并在不同的作用水平（生物，细胞和基因水平）下进行了研究。 。发现这两种农药，无论是单独使用还是组合使用，均会引起氧化应激，并导致C. dilutus致死。。IMI和AZO的致死浓度中位数分别为3.98±1.17和52.9±1.1μg/ L。两种农药的混合物在与环境有关的浓度下表现出协同作用，而在高浓度下表现出拮抗作用，表现出浓度依赖性的联合毒性。对cyt b，coi，cox1，cyp4，cyp12m1，cyp9au1，cyp6fv1，cyp315，gst，Zn / Cu-sod，Mn-sod和cat的12个基因的表达进行调查后发现，这两种农药会破坏线粒体呼吸，排毒。和抗氧化系统C. dilutus和两种农药的共同作用可能是由于它们各自对这些生理过程的影响之间的相互作用。总体而言，两种农药在与环境有关的浓度下的协同作用突显了将综合毒性研究纳入农药生态风险评估的重要性。