Scheu Stefan, Simmerling Frauke
Institut für Zoologie, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany.
Oecologia. 2004 May;139(3):347-53. doi: 10.1007/s00442-004-1513-7. Epub 2004 Mar 12.
Fungal feeding soil invertebrates feed on a wide spectrum of fungal species suggesting that mixed diets increase fitness. We investigated relationships between food preferences for seven saprophytic fungal species/forms and fitness parameters (mortality, growth, time to reproduction, reproduction, egg size) in two Collembola species, Folsomia candida and Protaphorura armata. The fungal species/forms studied included the wild type and a melanin-deficient form of Aspergillus fumigatus to investigate the role of melanin in collembolan nutrition. Also, three mixed diets consisting of a preferred fungal species (Cladosporium cladosporioides) and species of intermediate or low food quality were investigated. Both Collembola species preferred similar fungal species/forms as food. Food preference generally matched fitness parameters, i.e. growth and reproduction of Collembola was at a maximum when feeding on preferred fungi. This was not the case for A. fumigatus. The wild type and the melanin-deficient form ranked among the least preferred fungi. Growth and reproduction of Collembola were low when feeding on the wild type but high when feeding on the melanin-deficient form indicating that the Collembola misjudged the food quality of the latter in the preference tests. The results show for the first time that genes driving melanin syntheses (pksP) strongly affect the food quality of fungi for fungal feeding invertebrates. Feeding on mixed diets generally increased growth and reproduction of Collembola except when the diets included toxic species (Penicillium sp.). The results support the nutrient balance hypothesis and also show that the detection of toxic species in the diet is important. They indicate that the widespread generalist feeding mode of Collembola maximizes fitness if toxic fungal species are avoided. The fitness parameters growth, reproduction and time until onset of reproduction were correlated closely but egg volume, which also varied with fungal diet, correlated poorly with the other fitness parameters. Variation in egg size with fungal diet shows that the diet of Collembola may have transgenerational effects.
以真菌为食的土壤无脊椎动物以多种真菌物种为食，这表明混合饮食能提高适应性。我们研究了两种弹尾目昆虫，即白色符氏跳虫和武装原跳虫，对七种腐生真菌物种/形态的食物偏好与适应性参数（死亡率、生长、繁殖时间、繁殖、卵大小）之间的关系。所研究的真菌物种/形态包括野生型和烟曲霉的黑色素缺陷型，以研究黑色素在弹尾目昆虫营养中的作用。此外，还研究了三种由首选真菌物种（枝孢菌）与中等或低食物质量的物种组成的混合饮食。两种弹尾目昆虫都偏好类似的真菌物种/形态作为食物。食物偏好通常与适应性参数相匹配，即弹尾目昆虫以偏好的真菌为食时，生长和繁殖达到最大值。烟曲霉的情况并非如此。野生型和黑色素缺陷型在最不受欢迎的真菌中排名靠前。弹尾目昆虫以野生型为食时生长和繁殖较低，但以黑色素缺陷型为食时生长和繁殖较高，这表明弹尾目昆虫在偏好测试中误判了后者的食物质量。结果首次表明，驱动黑色素合成的基因（pksP）强烈影响以真菌为食的无脊椎动物所食用真菌的食物质量。以混合饮食为食通常会增加弹尾目昆虫的生长和繁殖，但当饮食中含有有毒物种（青霉属）时除外。这些结果支持了营养平衡假说，也表明检测饮食中的有毒物种很重要。它们表明，如果避免食用有毒真菌物种，弹尾目昆虫广泛的通才摄食模式能使适应性最大化。适应性参数生长、繁殖和繁殖开始前的时间密切相关，但卵体积也随真菌饮食而变化，与其他适应性参数的相关性较差。卵大小随真菌饮食的变化表明，弹尾目昆虫的饮食可能具有跨代效应。
