Suutari Erna, Rantala Markus J, Salmela Jukka, Suhonen Jukka
Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland.
Oecologia. 2004 Jun;140(1):135-9. doi: 10.1007/s00442-004-1559-6. Epub 2004 Apr 20.
We examined the effects of intraguild predation (IGP) and interference competition on an endangered dragonfly, Aeshna viridis Eversm. (Odonata: Anisoptera). A. viridis is rare in Europe due to the decrease in suitable habitats harboring the macrophyte Stratiotes aloides L. Stratiotes plants are the principal oviposition substrate for A. viridis females and protect the larvae of A. viridis from fish predation. In our study lakes A. viridis larvae are sympatric with larvae of Aeshna grandis and Aeshna juncea. The susceptibility of A. viridis larvae to IGP by similar-sized larvae of A. grandis and A. juncea was tested in a laboratory predation experiment. Microhabitat use of A. viridis and A. grandis was studied in the laboratory to determine the possible effects of interference competition on the spatial distribution of A. viridis larvae. Our results show that at least in laboratory conditions, A. viridis is susceptible to IGP and interference competition. In competition, A. grandis larvae dominated the middle and outer portion of S. aloides rosettes whereas A. viridis stayed in the inner parts. When A. grandis larvae were absent, A. viridis colonized the middle and outer parts of the rosettes. We conclude that asymmetric predation between odonate larvae of equal size can be intense, and that both IGP and interference competition affect A. viridis. Although natural habitat complexity diminishes their impact, these interactions may nevertheless influence the distribution of A. viridis in S. aloides waters and restrict its microhabitat use in S. aloides rosettes.
我们研究了集团内捕食（IGP）和干扰竞争对濒危蜻蜓——艾氏大蜓（Aeshna viridis Eversm.，蜻蜓目：差翅亚目）的影响。由于适合生长着大型水生植物莕菜（Stratiotes aloides L.）的栖息地减少，艾氏大蜓在欧洲十分罕见。莕菜植物是艾氏大蜓雌虫的主要产卵基质，并且能保护艾氏大蜓幼虫免受鱼类捕食。在我们研究的湖泊中，艾氏大蜓幼虫与巨圆臀大蜓（Aeshna grandis）和乌带尾蜓（Aeshna juncea）的幼虫同域分布。在一项实验室捕食实验中，测试了艾氏大蜓幼虫对体型相似的巨圆臀大蜓和乌带尾蜓幼虫的集团内捕食易感性。在实验室中研究了艾氏大蜓和巨圆臀大蜓的微生境利用情况，以确定干扰竞争对艾氏大蜓幼虫空间分布的可能影响。我们的结果表明，至少在实验室条件下，艾氏大蜓易受集团内捕食和干扰竞争的影响。在竞争中，巨圆臀大蜓幼虫占据了莕菜莲座叶丛的中部和外部，而艾氏大蜓则留在内部。当没有巨圆臀大蜓幼虫时，艾氏大蜓会在莲座叶丛的中部和外部栖息。我们得出结论，同等大小的蜻蜓目幼虫之间的不对称捕食可能很激烈，并且集团内捕食和干扰竞争都会影响艾氏大蜓。尽管自然栖息地的复杂性会减弱它们的影响，但这些相互作用仍可能影响艾氏大蜓在莕菜水域中的分布，并限制其在莕菜莲座叶丛中的微生境利用。
