Morris William F
Department of Zoology, NJ-15, University of Washington, 98195, Seattle, WA, USA.
Oecologia. 1992 Jun;90(3):359-365. doi: 10.1007/BF00317692.
I used a factorial experiment repeated in two years to assess the relative effects of natural enemy attack, interspecific competition, and water availability to the host plant, and of interactions among these factors, on the population dynamics of the aphid Aphis varians feeding on fireweed (Epilobium angustifolium). The impact of a suite of coccinellid and syrphid predators emerged as the predominant factor affecting the success of aphid colonies: colonies protected from natural enemies grew in size at a rate of ten percent per day, were only one tenth as likely to go extinct, and produced over ten times more dispersing alates. In contrast, I found only minor effects of removing flea beetles, the most abundant herbivore with which A. varians colonies cohabit fireweed stems, and of supplementing water availability to fireweed host plants, in spite of a significant effect of watering frequency on aphid growth in the green-house. There was no evidence of significant two- or three-way interactions among factors. Hence, despite the potential complexity of the food web in which it is embedded, the dynamics of A. varians appears to be driven predominantly by a single factor, i.e. interactions with natural enemies.
我进行了一项为期两年的析因实验，以评估天敌攻击、种间竞争、寄主植物水分可利用性以及这些因素之间的相互作用对以柳叶菜（Epilobium angustifolium）为食的变异蚜（Aphis varians）种群动态的相对影响。一系列瓢虫和食蚜蝇类捕食者的影响成为影响蚜虫群落成功的主要因素：免受天敌侵害的蚜群以每天10%的速度增长，灭绝的可能性只有十分之一，产生的扩散型有翅蚜数量多出十倍以上。相比之下，尽管浇水频率对温室中蚜虫的生长有显著影响，但我发现去除跳甲（与变异蚜群落共同栖息在柳叶菜茎上的数量最多的食草动物）以及增加柳叶菜寄主植物的水分可利用性的影响较小。没有证据表明各因素之间存在显著的二阶或三阶相互作用。因此，尽管变异蚜所处的食物网可能很复杂，但其动态似乎主要由单一因素驱动，即与天敌的相互作用。
