Department of Biological Sciences, The George Washington University, Washington, DC, USA.
J Anim Ecol. 2020 May;89(5):1165-1174. doi: 10.1111/1365-2656.13188. Epub 2020 Mar 16.
Deciphering the mechanisms that underpin dietary specialization and niche partitioning is crucial to understanding the maintenance of biodiversity. New world army ants live in species-rich assemblages throughout the Neotropics and are voracious predators of other arthropods. They are therefore an important and potentially informative group for addressing how diverse predator assemblages partition available prey resources. New World army ants are largely specialist predators of other ants, with each species specializing on different ant genera. However, the mechanisms of prey choice are unknown. In this study, we addressed whether the army ant Eciton hamatum: (a) can detect potential prey odours, (b) can distinguish between odours of prey and non-prey and (c) can differentiate between different types of odours associated with its prey. Using field experiments, we tested the response of army ants to the following four odour treatments: alarm odours, dead ants, live ants and nest material. Each treatment had a unique combination of odour sources and included some movement in two of the treatments (alarm and live ants). Odour treatments were tested for both prey and non-prey ants. These data were used to determine the degree to which E. hamatum are using specific prey stimuli to detect potential prey and direct their foraging. Army ants responded strongly to odours derived from prey ants, which triggered both increased localized recruitment and slowed advancement of the raid as they targeted the odour source. Odours from non-prey ants were largely ignored. Additionally, the army ants had the strongest response to the nest material of their preferred prey, with progressively weaker responses across the live ant, dead ant and alarm odours treatments respectively. This study reveals that the detection of prey odours, and especially the most persistent odours related to the prey's nest, provides a mechanism for dietary specialization in army ants. If ubiquitous across the Neotropical army ants, then this olfaction-based ecological specialization may facilitate patterns of resource partitioning and coexistence in these diverse predator communities.
破译支持饮食专业化和生态位分化的机制对于理解生物多样性的维持至关重要。新世界行军蚁生活在新热带地区丰富多样的物种组合中，是其他节肢动物的贪婪捕食者。因此，它们是一个重要的、具有潜在信息的群体，可以用来研究不同的捕食者组合如何划分可用的猎物资源。新世界行军蚁主要是其他蚂蚁的特化捕食者，每种蚂蚁都特化于不同的蚂蚁属。然而，猎物选择的机制尚不清楚。在这项研究中，我们探讨了行军蚁 Eciton hamatum 是否能够：(a) 检测到潜在的猎物气味，(b) 区分猎物和非猎物的气味，以及 (c) 区分与其猎物相关的不同类型的气味。我们使用野外实验，测试了行军蚁对以下四种气味处理的反应：警报气味、死蚂蚁、活蚂蚁和巢材。每种处理都有独特的气味来源组合，其中两种处理（警报和活蚂蚁）包括一些运动。测试了猎物和非猎物蚂蚁的气味处理。这些数据用于确定 E. hamatum 程度，即它们是否使用特定的猎物刺激来检测潜在的猎物并引导它们觅食。行军蚁对来自猎物蚂蚁的气味做出强烈反应，这既引发了对气味源的局部招募增加，又减缓了袭击的推进速度。非猎物蚂蚁的气味则被大部分忽略。此外，行军蚁对其首选猎物的巢材反应最强，随着活蚂蚁、死蚂蚁和警报气味处理的进行，反应逐渐减弱。这项研究表明，猎物气味的检测，特别是与猎物巢穴相关的最持久的气味，为行军蚁的饮食特化提供了一种机制。如果这种基于嗅觉的生态特化在新热带地区的行军蚁中普遍存在，那么这种嗅觉生态特化可能有助于这些多样化的捕食者群落中资源划分和共存模式。
