Dataset for: Acute effects of binary mixtures of imidacloprid and tebuconazole on 4 freshwater invertebrates

Receiving waters from agricultural areas can contain multiple pesticides such as the neonicotinoid imidacloprid and the fungicide tebuconazole, leading to the potential for aquatic life to be exposed to such mixtures. In the present study, the effects of tebuconazole were tested alone and in binary mixtures with imidacloprid on four aquatic invertebrates: Chironomus dilutus, Hyalella azteca, Lumbriculus variegatus, and Neocloeon triangulifer. Acute (96-h) LC50s were derived for individual compounds and used to design a binary mixture study to determine cumulative effects. LC50s showed imidacloprid was more potent than tebuconazole by 1–3 orders of magnitude for four species. Lethality data from mixture experiments were analyzed using MIXTOX to determine deviations from independent action (IA), followed by the model deviation ratio (MDR) technique to determine biological significance and reproducibility of observed mixture effects. MIXTOX showed cumulative toxicities of IMI-TBZ differed between the species; for C. dilutus there was no deviation from IA; however, for H. azteca the mixture was antagonistic (specifically dose-ratio dependent), and for N. triangulifer was synergistic. The MDR method showed that only observations with H. azteca significantly deviated from IA. Due to the lack of evidence of clear deviation from IA and the much greater potency of imidacloprid, the weight of evidence indicates the presence of tebuconazole is unlikely to appreciably increase the hazard from imidacloprid exposure to aquatic invertebrates.

农业区域的受纳水体中可能存在多种农药，如新烟碱类(neonicotinoid)杀虫剂吡虫啉(imidacloprid)与杀菌剂戊唑醇(tebuconazole)，这使得水生生物存在暴露于此类农药混合物的风险。本研究针对4种水生无脊椎动物——钝摇蚊(Chironomus dilutus)、阿兹特克钩虾(Hyalella azteca)、杂色颤蚓(Lumbriculus variegatus)以及三角新扁蜉(Neocloeon triangulifer)——分别测试了戊唑醇单独施用以及其与吡虫啉组成的二元混合物的毒性效应。研究首先测定了单种化合物的急性96小时半数致死浓度(LC50)，并以此为依据设计二元混合物实验以探究其联合毒性效应。半数致死浓度结果显示，对于4种受试生物而言，吡虫啉的毒性强度较戊唑醇高1~3个数量级。研究采用MIXTOX软件分析混合物实验的致死数据，以判断其是否偏离独立作用(IA)模型；随后通过模型偏差率(MDR)方法，评估观测到的联合毒性效应的生物学意义与可重复性。MIXTOX分析结果表明，吡虫啉-戊唑醇的联合毒性存在物种差异：对于钝摇蚊，其联合毒性未偏离独立作用模型；而对于阿兹特克钩虾，混合物表现为拮抗作用（且具体呈现剂量比依赖性）；对于三角新扁蜉，则表现为协同作用。模型偏差率分析结果显示，仅阿兹特克钩虾的实验数据显著偏离了独立作用模型。鉴于尚无明确证据表明联合毒性偏离独立作用模型，且吡虫啉的毒性强度远高于戊唑醇，综合证据权重表明，共存的戊唑醇不太可能显著增加水生无脊椎动物暴露于吡虫啉时所面临的危害风险。