Downstairs drivers - root herbivores shape communities of above-ground herbivores and natural enemies via changes in plant nutrients
Downstairs drivers - root herbivores shape communities of above-ground herbivores and natural enemies via changes in plant nutrients
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DOI：
10.1111/1365-2656.12070
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发表时间：
2013-09-01
影响因子：
4.8
通讯作者：
Karley, Alison J.
中科院分区：
文献类型：
--
作者：
Johnson, Scott N.;Mitchell, Carolyn;Karley, Alison J.
1.陆地食物网是由复杂的相互作用编织而成的，通常以植物介导的食草动物和高等营养群体之间的相互作用为基础。地下和地上的食草动物可以通过对共同宿主植物的诱导变化相互影响，从而可能塑造更广泛的群落。然而，迄今为止，将实验室观察与自然野外种群联系起来的经验证据尚不清楚。本研究在控制和田间条件下研究了食根象甲对食韧皮部蚜虫隐潜蚜和食叶叶蜂取食功能的影响.我们假设，根食草动物引起的植物营养（C、N、P和氨基酸）和防御化合物（酚类）的变化将支持根和叶食草动物之间的相互作用，并最终支持田间叶食草动物的天敌种群.象鼻虫增加田间蚜虫种群约。700%，其次是蚜虫天敌的丰度增加。象鼻虫增加了叶片必需氨基酸的比例，这种变化与蚜虫的丰度呈正相关，在对照试验中，象鼻虫植株上蚜虫的丰度增加了90%.相比之下，叶蜂种群在6月中旬减少了77%，在有象鼻虫的植物上成虫羽化延迟了> 14天。在对照实验中，象鼻虫使叶蜂的生长减少了18%，这与根食草动物引起的叶磷减少35%有关，这是一种以前未报道的地上-地下食草动物相互作用的机制。这代表了一个清楚的证明根食草动物影响叶面食草动物群落组成和天敌丰富的领域，通过两个不同的植物介导的营养机制。蚜虫种群，特别是，最初驱动的自下而上的影响（即植物介导的影响根草食动物），但随之而来的增加天敌触发自上而下的监管。
1. Terrestrial food webs are woven from complex interactions, often underpinned by plant-mediated interactions between herbivores and higher trophic groups. Below-and above-ground herbivores can influence one another via induced changes to a shared host plant, potentially shaping the wider community. However, empirical evidence linking laboratory observations to natural field populations has so far been elusive.2. This study investigated how root-feeding weevils (Otiorhynchus sulcatus) influence different feeding guilds of herbivore (phloem-feeding aphids, Cryptomyzus galeopsidis, and leaf-chewing sawflies, Nematus olfaciens) in both controlled and field conditions.3. We hypothesized that root herbivore-induced changes in plant nutrients (C, N, P and amino acids) and defensive compounds (phenolics) would underpin the interactions between root and foliar herbivores, and ultimately populations of natural enemies of the foliar herbivores in the field.4. Weevils increased field populations of aphids by ca. 700%, which was followed by an increase in the abundance of aphid natural enemies. Weevils increased the proportion of foliar essential amino acids, and this change was positively correlated with aphid abundance, which increased by 90% on plants with weevils in controlled experiments.5. In contrast, sawfly populations were 77% smaller during mid-June and adult emergence delayed by > 14 days on plants with weevils. In controlled experiments, weevils impaired sawfly growth by 18%, which correlated with 35% reductions in leaf phosphorus caused by root herbivory, a previously unreported mechanism for above-ground-below-ground herbivore interactions.6. This represents a clear demonstration of root herbivores affecting foliar herbivore community composition and natural enemy abundance in the field via two distinct plant-mediated nutritional mechanisms. Aphid populations, in particular, were initially driven by bottom-up effects (i.e. plant-mediated effects of root herbivory), but consequent increases in natural enemies triggered top-down regulation.