Gross Elisabeth M, Johnson Robert L, Hairston Nelson G
Limnological Institute, University of Konstanz, 78457, Konstanz, Germany.
Department of Ecology and Evolutionary Biology, Cornell University, 14853-2701, Ithaca, NY, USA.
Oecologia. 2001 Mar;127(1):105-114. doi: 10.1007/s004420000568. Epub 2001 Mar 1.
Our field observations on submersed macrophytes in the littoral zone of Cayuga Lake, N.Y., USA indicate that the shift in dominance from Myriophyllum spicatum L. to Elodea canadensis Michx. may be explained by the high abundance of an aquatic lepidopteran larva, Acentria ephemerella Denis & Schiffermüller. Experimental evidence for the preference of Acentria for Myriophyllum over Elodea was obtained from small-scale, short-term laboratory experiments and from a tank experiment that represents a spatial and temporal scale intermediate between that of the small-container laboratory study and whole-lake observations. In laboratory no-choice feeding assays, Acentria exhibited higher feeding rates on Myriophyllum than on Elodea. In choice experiments, the larvae clearly preferred Myriophyllum over Elodea. Mesocosm tanks were set up with both Myriophyllum and Elodea planted in patches, and larval densities of 0, 75, 200 and 400 larvae m. After 3 weeks, biomass and shoot length of Myriophyllum was inversely correlated with larval density, but biomass of Elodea was unaffected. In this study, we explore whether a generalist macroinvertebrate herbivore such as Acentria, by preference for one macrophyte species over others, may affect the competitive interaction between two rooted plant species and subsequently may change the community composition within submersed macrophyte beds.
我们对美国纽约州卡尤加湖沿岸带沉水大型植物的实地观察表明，优势种从穗状狐尾藻向加拿大伊乐藻的转变，可能是由一种水生鳞翅目幼虫——水螟（Acentria ephemerella Denis & Schiffermüller）的高丰度所致。通过小规模、短期的实验室实验以及一个水箱实验（该实验代表了介于小型容器实验室研究和全湖观测之间的时空尺度），获得了水螟对狐尾藻的偏好高于伊乐藻的实验证据。在实验室无选择取食试验中，水螟对狐尾藻的取食率高于伊乐藻。在选择实验中，幼虫明显更偏好狐尾藻而非伊乐藻。中宇宙水箱中种植了呈斑块状分布的狐尾藻和伊乐藻，并设置了每平方米有0、75、200和400只幼虫的密度。3周后，狐尾藻的生物量和茎长与幼虫密度呈负相关，但伊乐藻的生物量未受影响。在本研究中，我们探究了像水螟这样的广食性大型无脊椎动物食草动物，通过对一种大型植物物种的偏好超过其他物种，是否可能影响两种沉水植物物种之间的竞争相互作用，并随后改变沉水大型植物群落的组成。
