Institute for Environmental Sciences, University of Koblenz-Landau, Fortstraße 7, D-76829 Landau, Germany.
Institute for Environmental Sciences, University of Koblenz-Landau, Fortstraße 7, D-76829 Landau, Germany; Eußerthal Ecosystem Research Station, University of Koblenz-Landau, Birkenthalstraße 13, D-76857 Eußerthal, Germany.
Aquat Toxicol. 2019 Jan;206:33-42. doi: 10.1016/j.aquatox.2018.10.021. Epub 2018 Oct 29.
It is well-documented that fungicides can affect crustacean leaf shredders via two effect pathways, namely waterborne exposure and their diet (i.e., via dietary uptake of fungicides adsorbed to leaf material and an altered microorganism-mediated food quality). As a consequence of different life history strategies, the relevance of these effect pathways for aquatic shredders belonging to other taxonomic classes, for instance insects, remains unclear. Therefore, we investigated waterborne and diet-related effects in larvae of the caddisfly leaf shredder Chaetopteryx villosa (Insecta: Trichoptera) and compared our observations to previous reports on effects in adults of the crustacean leaf shredder Gammarus fossarum (Malacostraca: Amphipoda). We assessed acute waterborne effects of an organic fungicide mixture (OFM) and the inorganic fungicide copper (Cu) on the leaf consumption (n = 30) of the fourth-/fifth-instar larvae of C. villosa and their food choice (n = 49) when offered leaf material, which was either conditioned in presence or in absence of the respective fungicide(s). Moreover, the larval leaf consumption (n = 50) and physiological fitness (i.e., growth as well as lipid and protein content) were examined after subjecting C. villosa for 24 days towards the combination of both effect pathways at environmentally relevant concentrations. G. fossarum and C. villosa exhibited similar sensitivities and the same effect direction when exposed to the OFM (either waterborne or dietary pathways). Both shredders also showed the same effect direction when exposed to dietary Cu, while with regards to mortality and leaf consumption C. villosa was less sensitive to waterborne Cu than G. fossarum. Finally, as observed for G. fossarum, the combined exposure to OFM over 24 days negatively affected leaf consumption and the physiology (i.e., growth and lipid reserves) of C. villosa. While no combined Cu effects were observed for larval leaf consumption, contrasting to the observations for G. fossarum, the physiology of both shredders was negatively affected, despite partly differing effect sizes and directions. Our results suggest that C. villosa and G. fossarum are of comparable sensitivity towards waterborne and diet-related organic fungicide exposure, whereas the trichopteran is less sensitive to Cu-based waterborne fungicide exposure. However, when both pathways act jointly, organic and inorganic fungicides can affect the physiology of shredder species with completely different life history strategies. As caddisflies represent a subsidy for terrestrial consumers, these observations indicate that fungicide exposure might not only affect aquatic ecosystem functioning but also the flux of energy across ecosystem boundaries.
有大量文献记载，杀菌剂可以通过两种作用途径影响甲壳类叶碎屑动物，即通过水暴露和它们的饮食（即通过饮食摄入吸附在叶材料上的杀菌剂和微生物介导的食物质量变化）。由于不同的生活史策略，这些作用途径对于属于其他分类类群的水生碎屑动物的相关性，例如昆虫，仍然不清楚。因此，我们研究了鳞翅目幼虫（昆虫纲：毛翅目）的水暴露和饮食相关影响，并将我们的观察结果与以前关于甲壳类叶碎屑动物（端足目：十足目）成虫的影响的报告进行了比较。我们评估了一种有机杀菌剂混合物（OFM）和无机杀菌剂铜（Cu）对第四/五龄幼虫（C. villosa）的叶片消耗（n=30）的急性水暴露效应，以及当提供叶片材料时，它们的食物选择（n=49），叶片材料是在存在或不存在各自的杀菌剂的情况下进行处理的。此外，在以环境相关浓度通过两种作用途径对 C. villosa 进行 24 天处理后，还检查了幼虫的叶片消耗（n=50）和生理适应性（即生长以及脂质和蛋白质含量）。当暴露于 OFM（无论是水暴露途径还是饮食途径）时，G. fossarum 和 C. villosa 表现出相似的敏感性和相同的作用方向。当暴露于饮食铜时，两种碎屑动物也表现出相同的作用方向，而对于死亡率和叶片消耗，C. villosa 对水暴露铜的敏感性低于 G. fossarum。最后，与 G. fossarum 的观察结果一样，在 24 天内，联合暴露于 OFM 对 C. villosa 的叶片消耗和生理（即生长和脂质储备）产生负面影响。虽然幼虫的叶片消耗没有观察到联合铜的影响，但与 G. fossarum 的观察结果相反，尽管作用大小和方向部分不同，但两种碎屑动物的生理都受到了负面影响。我们的结果表明，C. villosa 和 G. fossarum 对水暴露和饮食相关有机杀菌剂暴露的敏感性相当，而鳞翅目幼虫对基于铜的水暴露杀菌剂的敏感性较低。然而，当两种途径共同作用时，有机和无机杀菌剂会影响具有完全不同生活史策略的碎屑动物物种的生理。由于鳞翅目幼虫是陆地消费者的一种补充，这些观察结果表明，杀菌剂暴露不仅会影响水生生态系统的功能，还会影响生态系统边界的能量流动。
