Ecological Networks, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 3, 64287, Darmstadt, Germany.
Sci Rep. 2017 Sep 22;7(1):12141. doi: 10.1038/s41598-017-12265-y.
At the basis of a trophic web, coprophagous animals like dung beetles (Scarabaeoidea) utilize resources that may have advantages (easy gain and handling) as well as drawbacks (formerly processed food). Several studies have characterized the nutrients, e.g. C/N ratios and organic matter content, for specific types of dung. However, a comparative approach across dung types and feeding guilds of dung producers, and relationships between dung nutrients and preferences by coprophages, have been missing. Hence, we analyzed water content, C/N ratio, amino acid, neutral lipid fatty acid, free fatty acid and sterol composition and concentrations in dung from 23 vertebrates, including carnivore, omnivore and herbivore species. Our analyses revealed significant differences among the three vertebrate feeding guilds for most nutritional parameters. Although formerly processed, dung grants sufficient amounts of essential nutrients for insects. We tested whether nutrients can explain the dung beetles' preferences in a field experiment, using 12 representative dung types in baits that were installed in 27 forests and 27 grasslands. Although consistent preferences for specific dung types were pronounced, the nutritional composition did not predict the variation in attractiveness of these dung diets, suggesting a primary role of dung volatiles irrespective of food quality.
在营养级联的基础上，食粪动物（如蜣螂科）利用可能具有优势（易于获取和处理）和劣势（先前处理过的食物）的资源。已有多项研究对特定类型的粪便中的营养成分（例如 C/N 比和有机质含量）进行了描述。然而，跨粪类型和粪生产者的食粪动物觅食群的比较方法，以及粪养分与食粪动物偏好之间的关系，仍然缺失。因此，我们分析了来自 23 种脊椎动物（包括肉食性、杂食性和草食性物种）的粪便中的水分含量、C/N 比、氨基酸、中性脂质脂肪酸、游离脂肪酸和甾醇组成和浓度。我们的分析表明，在大多数营养参数方面，这三个脊椎动物觅食群之间存在显著差异。尽管是先前处理过的，但粪便为昆虫提供了足够数量的必需营养物质。我们在野外实验中测试了这些营养物质是否可以解释蜣螂的偏好，使用了 12 种有代表性的粪便类型作为诱饵，这些诱饵被安装在 27 片森林和 27 片草地中。尽管对特定粪便类型的偏好明显一致，但营养成分并不能预测这些粪便饮食的吸引力的变化，这表明粪挥发物的主要作用，而不考虑食物质量。
