iES Landau, Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
Institute of Organismic and Molecular Evolution, Biocentre I, University of Mainz, Mainz, Germany.
J Anim Ecol. 2020 Jul;89(7):1690-1700. doi: 10.1111/1365-2656.13224. Epub 2020 Apr 11.
Predator non-consumptive effects (NCE) are a suite of phenotypic responses of prey to avoid predation that cascade down food webs and can have a stronger impact than predation itself. However, the role of NCE in intraguild interactions remains understudied. Thus, multi-species experiments based on species traits are needed to improve our understanding of the impact of NCE on community structure. We investigated NCE of ants on 17 spider species as intraguild prey (8 cursorial and 9 sedentary) to test the influence of spider hunting mode on the strength of NCE. Sedentary spiders select a habitat patch and wait for prey, whereas cursorial spiders roam around searching for prey. Because actively foraging organisms have higher encounter rates with predators, cursorial spiders should show stronger reactions to ant presence. We collected cues (footprint hydrocarbons) of the black garden ant Lasius niger on filter papers. Then, we placed spiders individually on the papers and filmed their behaviour once on a paper with cues and once on a cue-free one. We used the increase in walking activity in the presence of cues as an indicator of avoidance behaviour towards ants. Cursorial spiders spent a longer time moving and being mobile, and had a higher overall mean mobility when exposed to ant cues compared with blank filter papers, whereas sedentary spider species did not react to ant cues at all. The avoidance of ant cues by cursorial spiders corresponds to their higher risk of encountering ants compared with sedentary species, in accordance with the threat-sensitivity hypothesis. Our multi-species study shows the relevance of NCE for intraguild interactions and highlights the importance of experimental trait-based approaches to improve predictability of species interactions and the role of NCE in ecological communities.
捕食者非消耗性效应（NCE）是猎物避免被捕食的一系列表型反应，这些反应在食物网中呈级联式传递，其影响可能比捕食本身更强烈。然而，NCE 在种间相互作用中的作用仍未得到充分研究。因此，需要基于物种特征的多物种实验来提高我们对 NCE 对群落结构影响的理解。我们研究了蚂蚁对 17 种蜘蛛物种（8 种游走性和 9 种定居性）的 NCE，以测试蜘蛛捕食模式对 NCE 强度的影响。定居性蜘蛛选择一个栖息地斑块并等待猎物，而游走性蜘蛛则四处漫游寻找猎物。因为主动觅食的生物与捕食者的遭遇率更高，所以游走性蜘蛛应该对蚂蚁的存在表现出更强的反应。我们收集了黑花园蚁 Lasius niger 的足迹碳氢化合物作为线索，将这些线索放在滤纸上。然后，我们将蜘蛛单独放在纸上，并在有线索的纸上和无线索的纸上各拍摄一次它们的行为。我们使用存在线索时的行走活动增加作为回避行为的指标。与无线索的滤纸相比，游走性蜘蛛在暴露于蚂蚁线索时，移动和活动的时间更长，整体平均移动性更高，而定居性蜘蛛物种则根本没有对蚂蚁线索做出反应。游走性蜘蛛回避蚂蚁线索的行为与其与定居性物种相比遭遇蚂蚁的风险更高相对应，符合威胁敏感性假说。我们的多物种研究表明 NCE 对种间相互作用的重要性，并强调了基于实验特征的方法在提高物种相互作用预测能力和 NCE 在生态群落中的作用方面的重要性。
