Reciprocal effects of host plant and natural enemy diversity on herbivore suppression: an empirical study of a model tritrophic system
Reciprocal effects of host plant and natural enemy diversity on herbivore suppression: an empirical study of a model tritrophic system
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DOI：
10.1111/j.0030-1299.2005.13418.x
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发表时间：
2005-02-01
期刊：
影响因子：
3.4
通讯作者：
Ives, AR
中科院分区：
文献类型：
--
作者：
Aquilino, KM;Cardinale, BJ;Ives, AR
许多理论和实证研究表明，营养级的物种多样性可以影响有限资源的捕获，其方式是沿着食物网向上或向下级联。然而，直到最近，生态学家才开始考虑多个营养级的多样性如何协同作用，对资源利用产生相反或加强的影响。在这里，我们报告的一个模型的实证研究结果，三营养食物网中，我们操纵的寄主植物物种（苜蓿，红车轴草和蚕豆）和天敌物种（异色瓢虫，Coleomegilla maculata和Nabis sp.）的多样性。一种广泛分布的食草性害虫（豌豆蚜，Acyrthosiphon pisum）在实验室的缩影。我们发现，增加天敌丰富度从一个到三个物种增加了0.14蚜虫消耗的比例。这种影响的敌人多样性是由于促进相互作用和/或减少种内竞争在更多样化的组合。我们还发现了一个独立的和加性的主效应的寄主植物丰富度，与蚜虫消耗的比例减少了0.14，在植物混养天敌。减少捕食者的效率对一个单一的宿主植物，蚕豆，似乎是负责这种植物多样性的影响。蚜虫种群规模，因此，同时决定了自上而下的天敌多样性的影响，和相反的自下而上的宿主植物多样性的影响，修改敌人-猎物的相互作用。这些结果表明，在自然界中的人口规模，生物控制害虫，在多个营养级的物种多样性的影响。
Many theoretical and empirical studies have shown that species diversity in a trophic level can impact the capture of limited resources in ways that cascade up or down a food web. Only recently, however, have ecologists begun to consider how diversity at multiple trophic levels might act in concert to have opposing or reinforcing effects on resource use. Here, we report the results of an empirical study of a model, tritrophic food web in which we manipulated the diversity of host plant species (Medicago sativa, Trifolium pratense and Vicia faba) and natural enemy species (Harmonia axyridis, Coleomegilla maculata and Nabis sp.) of a widespread herbivorous pest (the pea aphid, Acyrthosiphon pisum) in laboratory microcosms. We found that increasing natural enemy richness from one to three species increased the proportion of aphids consumed by 0.14. This effect of enemy diversity was due to facilitative interactions and/or a reduction in intraspecific competition in the more diverse assemblages. We also found an independent and additive main effect of host plant richness, with the proportion of aphids consumed by natural enemies decreasing by 0.14 in plant polycultures. A reduction in predator efficiency on a single host plant, Vicia faba, appeared to be responsible for this plant diversity effect. Aphid population sizes were, therefore, simultaneously determined by a top-down effect of natural enemy diversity, and an opposing bottom-up effect of host plant diversity that modified enemy-prey interactions. These results suggest that population sizes in nature, and biotic controls over insect pests, are influenced by species diversity at multiple trophic levels.