Stable Isotope Trophic Fractionation (13C/12C and 15N/14N) in Mycophagous Diptera Larvae
Stable Isotope Trophic Fractionation (13C/12C and 15N/14N) in Mycophagous Diptera Larvae
复制标题
菌食性双翅目幼虫中的稳定同位素营养级分离（13C/12C 和 15N/14N）
作者：
A. Zuev;O. L. Rozanova;S. Tsurikov;P. Panchenko;M. A. Ershova;D. Smolyarova;M. Krivosheina;A. V. Aleksandrova;S. B. Ivnitsky;Y. Maleeva;A. Tiunov
利用同位素分析重建食物网结构需要确定碳和氮稳定同位素（Δ 13 C和Δ 15 N）的营养分馏。真菌和食菌动物在土壤群落中起着关键作用，但关于以真菌为食的动物的同位素分馏程度的实地数据非常有限。我们研究了大量的同位素组成的食菌双翅目幼虫栖息在子实体的腐食性和菌根大型真菌，以及幼虫喂养的寄生锈菌。以锈菌为食的瘿蚊Mycodiplosis sp.幼虫对13 ‰和15 ‰ N的营养富集最低，分别为0.0和0.9‰。寄生于腐殖型和菌根型大型真菌子实体的双翅目幼虫的Δ 13 C和Δ 15 N值分别为0.9 ‰和3.4‰。这与放牧食物链中通常观察到的值相对应。15 N的积累是更明显的幼虫，以腐食性真菌，但没有明确的关系被发现之间的营养分馏的程度和动物或真菌的分类隶属关系。正如我们的数据和已发表的研究分析所建议的，在营养级分离的真菌的变化是强大的，但他们不太可能阻碍识别的“菌根”和“腐殖”的能量通道在土壤食物网。
The use of isotopic analysis for reconstructing the structure of food webs requires determination of the trophic fractionation of carbon and nitrogen stable isotopes (Δ13C and Δ15N). Fungi and mycophagous animals play a key role in soil communities, but there are very limited field data on the degree of isotope fractionation in animals that feed on fungi. We studied the bulk isotopic composition of mycetophagous Diptera larvae inhabiting fruit bodies of saprotrophic and mycorrhizal macromycetes, as well as larva feeding on parasitic rust fungi. Trophic enrichment in 13С and 15N was at the minimum (0.0 and 0.9‰, respectively) in the larvae of gall midges Mycodiplosis sp. feeding on rust fungi (Pucciniales). In the larvae of dipterans inhabiting fruiting bodies of saprotrophic and mycorrhizal macromycetes, the Δ13C and Δ15N values averaged 0.9 and 3.4‰, respectively. This corresponds to the values usually observed in grazing food chains. The accumulation of 15N was more pronounced in the larvae that fed on saprotrophic fungi, but no clear relationship was found between the degree of trophic fractionation and the taxonomic affiliation of animals or fungi. As suggested by our data and the analysis of published studies, the variations in the trophic fractionation in mycophages are strong, but they are not likely to impede the identification of the “mycorrhizal” and “saprotrophic” energy channels in the soil food webs.