Data from: Interplay between fungicides and parasites: tebuconazole, but not copper, suppresses infection in a Daphnia-Metschnikowia experimental model

Natural populations are commonly exposed to complex stress scenarios, including anthropogenic contamination and their biological enemies (e.g., parasites). The study of the pollutant-parasite interplay is especially important, given the need for adequate regulations to promote improved ecosystem protection. In this study, a host-parasite model system (Daphnia spp. and the microparasitic yeast Metschnikowia bicuspidata) was used to explore the reciprocal effects of contamination by common agrochemical fungicides (copper sulphate and tebuconazole) and parasite challenge. We conducted 21-day life history experiments with two host clones exposed to copper (0.00, 25.0, 28.8 and 33.1 μg L-1) or tebuconazole (0.00, 154, 192 and 240 μg L-1), in the absence or presence of the parasite. For each contaminant, the experimental design consisted of 2 Daphnia clones × 4 contaminant concentrations × 2 parasite treatments × 20 replicates = 320 experimental units. Copper and tebuconazole decreased Daphnia survival or reproduction, respectively, whilst the parasite strongly reduced host survival. Most importantly, while copper and parasite effects were mostly independent, tebuconazole suppressed infection. In a follow-up experiment, we tested the effect of a lower range of tebuconazole concentrations (0.00, 6.25, 12.5, 25.0, 50.0 and 100 μg L-1) crossed with increasing parasite challenge (2 Daphnia clones × 6 contaminant concentrations × 2 parasite levels × 20 replicates = 480 experimental units). Suppression of infection was confirmed at environmentally relevant concentrations (> 6.25 μg L-1), irrespective of the numbers of parasite challenge. The ecological consequences of such a suppression of infection include interferences in host population dynamics and diversity, as well as community structure and energy flow across the food web, which could upscale to ecosystem level given the important role of parasites.

自然种群通常会面临复杂的胁迫情境，包括人为污染及其生物天敌（如寄生虫）。鉴于需要制定合理的监管政策以提升生态系统保护水平，针对污染物-寄生虫互作（pollutant-parasite interplay）的研究尤为重要。本研究以宿主-寄生虫模型系统（host-parasite model system）——溞属（Daphnia）物种与微寄生酵母二孢梅奇酵母（Metschnikowia bicuspidata）——为研究对象，探究常见农用杀菌剂硫酸铜（copper sulphate）与戊唑醇（tebuconazole）的污染与寄生虫侵染之间的交互效应。我们开展了为期21天的生活史实验，设置两组宿主克隆株，分别暴露于不同浓度的硫酸铜（0.00、25.0、28.8和33.1 μg·L⁻¹）或戊唑醇（0.00、154、192和240 μg·L⁻¹）环境中，同时设置寄生虫存在与不存在两种处理。针对每种污染物，实验设计为：2个溞属克隆株 × 4个污染物浓度梯度 × 2种寄生虫处理 × 20个重复 = 320个实验单元。实验结果显示，硫酸铜会降低溞的存活率，戊唑醇则会抑制其繁殖，而寄生虫侵染会显著降低宿主存活率。最为关键的是，硫酸铜与寄生虫的效应大多相互独立，而戊唑醇却能抑制寄生虫侵染。在后续实验中，我们测试了更低浓度梯度的戊唑醇（0.00、6.25、12.5、25.0、50.0和100 μg·L⁻¹）与递增的寄生虫侵染强度的交互效应，实验设计为：2个溞属克隆株 × 6个污染物浓度梯度 × 2种寄生虫侵染水平 × 20个重复 = 480个实验单元。实验证实，在环境相关浓度（>6.25 μg·L⁻¹）下，戊唑醇均可抑制寄生虫侵染，且该效应不受寄生虫侵染强度的影响。这种寄生虫侵染抑制现象所带来的生态后果包括干扰宿主种群动态与多样性、群落结构以及食物网中的能量流动，考虑到寄生虫在生态系统中发挥的重要作用，这些影响可能会升级至生态系统层面。