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社区。水分限制会影响食草动物作为食物的植物的数量和质量，还会通过猎物质量的变化和适宜生境的减少而影响营养级别较高的消费者。我们的研究评估了节肢动物群落对水分有限的小麦（Triticum aestivum）的反应L.）在字段设置中。我们使用了防雨棚排除了降水，使用了灌溉的高架床田以创造三个水平的水供应，并在8周内监控了节肢动物群落的发育。首先，我们比较了节水程度不同的生境中的节肢动物群落，发现群落组成取决于水分胁迫的程度。这种差异主要是由于在高压力环境下刺穿食草动物和天敌的损失。接下来，我们重点研究蚜虫及其天敌，以利用结构方程模型（SEM）研究驱动群落响应的潜在机制。蚜虫的丰度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。在水有限的栖息地中，天敌的丰度也降低了，但是天敌对植物的生物量做出了反应，而不是猎物的可利用性。随着水分胁迫的增加，这些影响会加剧。没有对蚜虫的天敌作用，表明自上而下的捕食作用被植物水分限制的强烈的自下而上的作用所削弱。这项研究揭示了预测节肢动物群落干旱后果时考虑水分胁迫强度的重要性。没有对蚜虫的天敌作用，表明自上而下的捕食作用被植物水分限制的强烈的自下而上的作用所削弱。这项研究揭示了预测节肢动物群落干旱后果时考虑水分胁迫强度的重要性。没有对蚜虫的天敌作用，表明自上而下的捕食作用被植物水分限制的强烈的自下而上的作用所削弱。这项研究揭示了预测节肢动物群落干旱后果时考虑水分胁迫强度的重要性。