Direct and Indirect Effects on the Trophic Dynamics of Holly Leaf Miner Populations

对冬青潜叶蝇种群营养动态的直接和间接影响

• 批准号: 9628929
• 负责人: Howard Cornell
• 金额: $ 12.5万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-10-01 至 2001-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9628929&HistoricalAwards=false
• 关键词: Direct; Indirect; Effects; Trophic; Dynamics

9628929 Cornell Whether top-down effects due to enemies or bottom-up effects due to resources control the dynamics of herbivore populations has been a venerable and divisive controversy in ecology. With the realization that natural systems are diverse and heterogeneous the argument has become sterile, and the focus must shift to the relative importance of these two forces and what controls them in different environments. Moreover, it has recently become obvious that exploring these interactions thoroughly requires differentiation between direct and indirect effects. Indirect effects mean that the intensity and symmetry of an interaction between two species may be altered by the presence of a third. For example, plant defenses might be able to reduce herbivore abundances but only in the presence of natural enemies because the primary effect of the defense is to make the herbivore more susceptible to attack. In this study, the investigators are employing a multi-pronged approach using a combination of experiments and statistical path analysis to study top-down and bottom-up effects on the distribution and abundance of the holly leaf miner on American holly. A combination of path analysis and experiments provides a new way of increasing inferential power beyond what is possible when either technique is used separately. The investigators have measured heterogeneity of plant quality and enemy abundance for the holly leaf miner and its host and are now setting up factorial experiments to test their direct and indirect effects on miners. This will be the first study to use such an integrated approach to answer fundamental questions about the structure and function of terrestrial food webs. It should have special relevance to theories of trophic dynamics as well as to the applied areas of forest pest management and biological control.

究竟是天敌的自上而下效应还是资源的自下而上效应控制了食草动物种群的动态，这在生态学中一直是一个令人尊敬的和有分歧的争论。 随着认识到自然系统是多样性和异质性的，争论已经变得毫无意义，焦点必须转移到这两种力量的相对重要性以及在不同环境中控制它们的因素。 此外，最近变得明显的是，彻底探索这些相互作用需要区分直接和间接影响。 间接效应意味着两个物种之间相互作用的强度和对称性可能会因第三个物种的存在而改变。 例如，植物防御可能能够减少食草动物的丰度，但只有在天敌存在的情况下，因为防御的主要作用是使食草动物更容易受到攻击。 在这项研究中，研究人员采用多管齐下的方法，结合实验和统计路径分析，研究自上而下和自下而上对美国冬青上冬青叶潜蝇分布和丰度的影响。 路径分析和实验的结合提供了一种新的方法，可以增加推理能力，超出单独使用任何一种技术时的可能性。 研究人员已经测量了冬青潜叶虫及其宿主的植物质量和敌人丰度的异质性，现在正在建立析因实验来测试它们对矿工的直接和间接影响。 这将是第一项使用这种综合方法来回答有关陆地食物网结构和功能的基本问题的研究。 它不仅与营养动力学理论有关，而且与森林害虫管理和生物防治的应用领域有关。