Non-consumptive effects of spiders on herbivore and carnivore prey: occurrence, importance, and mechanisms

在营养相互作用中，捕食者通过捕食对猎物种群的影响往往被捕食者对猎物行为的非消耗性影响所超过。蜘蛛可以在昆虫和其他蜘蛛身上引发强烈的反捕食者行为。然而，只有在数量有限的昆虫和蜘蛛物种中才对反捕食者行为进行了研究。此外，在陆地系统中，涉及到检测捕食风险(即捕食者的存在)的机制还很少被探索。在子项目A中，我们将调查18种蜘蛛和18种昆虫的反捕食者行为的发生和强度，这些物种涵盖了广泛的分类范围。研究物种的选择将允许测试生活史特征对反捕食者行为的影响。特征包括捕食者的狩猎方式，捕食者和猎物的相对身体大小，猎物的营养水平，生态位宽度和扩散能力。测量的反捕食者行为将包括小规模移动和长距离扩散的倾向。此外，将在野外测试捕食者线索对植物性能的影响。在子项目B中，我们将使用生物分析和分析方法来研究蜘蛛捕食者的存在是如何被猎物物种检测到的。蜘蛛丝、粪便、化学足迹和空气中的挥发性线索将被区分为捕食风险检测的途径。此外，蜘蛛丝的机械和化学线索将被分离。我们将测试是否通过触觉、嗅觉和/或接触化学接收来检测捕食风险。最后，将利用气相色谱和质谱仪对风险检测中涉及的物质进行鉴定。

In trophic interactions, predator effects on prey populations through consumption are often exceeded by non-consumptive effects that predators elicit on prey behavior. Spiders can elicit strong antipredator behavior in both insects and other spiders. However, antipredator behavior has only been investigated in a limited number of insect and spider species. In addition, the mechanisms involved in the detection of predation risk (i.e., predator presence) have rarely been explored in terrestrialsystems.In subproject A, we will investigate the occurrence and strength of antipredator behavior across 18 spider and 18 insect species that cover a wide taxonomic range. The selection of study species will allow to test effects of life-history traits on the magnitude of antipredator behavior. Traits include hunting mode of the predator, relative body size of predator and prey, trophic level, niche width and dispersal ability of the prey. Measured antipredator behavior will include both small-scale movement and the propensity for long-distance dispersal. Furthermore, effects of the presence of predator cues on plant performance will be tested in the field.In subproject B, we will use bioassays and analytical methods to investigate how the presence of spider predators is detected by prey species. Spider silk, feces, chemical footprints, and airborne volatile cues will be distinguished as pathways for predation risk detection. Further, mechanical and chemical cues of spider silk will be separated. We will test if predation risk is detected via tactile senses, olfaction and/or contact chemoreception. Finally, the substances involved in risk detection will be identified using gas chromatography and mass spectrometry.