Division of Plant Sciences, University of Missouri, Columbia, MO, 65211, USA.
Department of Entomology, Washington State University, Pullman, WA, 99163, USA.
Oecologia. 2021 Apr;195(4):833-842. doi: 10.1007/s00442-020-04844-0. Epub 2021 Jan 15.
Drought threatens arthropod communities worldwide. Water limitation affects the quantity and quality of plants available to herbivores as food, and can also affect higher trophic-level consumers through variability in prey quality and reduced availability of suitable habitats. Our study assessed the response of an arthropod community to water limited wheat (Triticum aestivum L.) in a field setting. We used rainout shelters to exclude precipitation, irrigated raised bed plots to create three levels of water availability, and monitored arthropod community development over 8 weeks. First, we compared arthropod communities in habitats with different levels of water limitation and found that community composition was reliant on the magnitude of the water stress. This difference was largely due to the loss of piercing-sucking herbivores and predators in high-stress environments. Next, we focused on aphids and their natural enemies to investigate the underlying mechanisms driving community responses using structural equation modeling (SEM). Aphid abundance was negatively affected by water limitation, and this response was primarily associated with stress-induced plant physiological changes and not plant biomass or natural enemy abundance. Natural enemy abundance was also reduced in water-limited habitats, but natural enemies responded to plant biomass and not prey availability. These effects were exacerbated as water stress increased. The absence of natural enemy effects on aphids indicates that top-down predation effects were dampened by strong bottom-up effects of plant water limitation. This study revealed the importance of considering water stress intensity when predicting outcomes of droughts for arthropod communities.
干旱威胁着全球的节肢动物群落。水分限制会影响到食草动物可用的植物的数量和质量，而且还会通过猎物质量的变化和适宜栖息地的减少来影响更高营养级的消费者。我们的研究评估了节肢动物群落对田间限水小麦（Triticum aestivum L.）的反应。我们使用雨水隔离棚来排除降水，灌溉高架床plots 来创造三种水分可利用水平，并监测了 8 周内节肢动物群落的发展。首先，我们比较了不同水分限制水平下栖息地的节肢动物群落，发现群落组成依赖于水分胁迫的程度。这种差异主要是由于高胁迫环境中穿刺吸食性食草动物和捕食者的丧失。接下来，我们专注于蚜虫及其天敌，通过结构方程模型（SEM）来研究驱动群落响应的潜在机制。蚜虫数量受到水分限制的负面影响，这种反应主要与胁迫诱导的植物生理变化有关，而与植物生物量或天敌丰度无关。在水分受限的栖息地中，天敌丰度也降低了，但天敌对植物生物量而不是猎物丰度做出反应。随着水分胁迫的增加，这些影响加剧了。天敌对蚜虫没有影响表明，由于植物水分限制的强烈自上而下的影响，捕食作用的自上而下效应被削弱了。本研究揭示了在预测干旱对节肢动物群落的影响时，考虑水分胁迫强度的重要性。
