Landscape Heterogeneity, Patch Connectivity, and Host-Parasitoid Population Dynamics

景观异质性，斑块连通性和寄主-寄生虫种群动态NSF生态研究基金（DEB-0211359）2002年9月1日-2005年8月31日自然栖息地的破碎化和丧失是一个可怕的世界性问题。 生态学家在理解栖息地破碎化或空间斑块化的增加可能对捕食者-被捕食者种群的长期持续性产生的影响方面取得了重大进展。 然而，大多数碎片化研究忽略了斑块之间存在的植被覆盖（称为矩阵），一般假设矩阵是无特征的，中性的捕食者和猎物物种的运动和种群波动。 实际上，矩阵是复杂和不断变化的。 基质组成的任何改变都可能显著影响捕食者与猎物的互动方式。 该建议概述了一个研究过程，旨在解决不同的矩阵类型如何影响草食动物及其捕食者的运动和种群波动。 在美国大平原的大草原灯心草的离散补丁之间分布的稻飞虱，Prokelisia crocea，和寄生蜂，Anagrus columbi，形成了一个理想的系统，这种类型的研究。 这项提议的关键是一个相对大规模的田间实验，旨在改变稻飞虱和黄蜂在斑块之间移动的能力（即，斑块连通性）通过将灯心草斑块嵌入两种主要基质类型（泥滩或外来草种雀麦）中的任一种。 移民，移民，空间传播的模式，和补丁内的昆虫分布将进行评估，从荧光标记的个人夺回。 该实验还将在3个空间尺度和6代上进行，以提供有关矩阵操作对斑块之间和随着时间的推移的寄生率和密度波动的影响的信息。 以前从未有过的补丁结构和矩阵被操纵在捕食者-猎物种群研究领域。 作为该田间试验的补充，还将进行试验以确定稻飞虱和黄蜂依赖于基质的运动模式的行为基础。 最后，将根据上述研究中获得的信息，开发一个模拟模型，以评估生境破碎化和退化的影响（例如，景观矩阵的变化）对捕食者-被捕食者相互作用的长期持续性的影响。NSF资助DEB-9973789的更新结果应该提供异质景观对捕食者-猎物相互作用的影响的关键和急需的信息，并希望催化更广泛的方法来研究捕食者-猎物相互作用。 这项研究也对保护计划产生了广泛的影响，这些保护计划对保护区的连通性感兴趣：一个有利于分散的矩阵（即，高质量的矩阵）可以起到与踏脚石或走廊相同的作用。 最后，这项研究可能对采用故意修改矩阵的策略（例如，通过间作、梯田化或让一些田地休耕）。 了解这些变化对害虫和天敌运动和相互作用的影响，可能是制定一个成功的害虫控制计划的关键。

Landscape heterogeneity, patch connectivity, and host-parasitoid population dynamicsNSF Ecological Studies Grant (DEB-0211359)September 1, 2002 - August 31, 2005 The fragmentation and loss of natural habitats is a dire world-wide problem. Ecologists have made significant in-roads toward understanding the impact that increased habitat fragmentation or spatial patchiness might have on the long-term persistence of predator-prey populations. However, most fragmentation studies have disregarded the vegetational cover that exists between patches (known as the matrix), generally assuming that the matrix is featureless and neutral to the movements and population fluctuations of both predator and prey species. In reality, the matrix is complex and ever-changing. Any alteration in matrix composition may significantly impact how predators interact with their prey. This proposal outlines a course of study designed to address how different matrix types influence the movement and population fluctuations of an herbivore and its predator. The planthopper, Prokelisia crocea, and the parasitoid wasp, Anagrus columbi, which are distributed among discrete patches of prairie cordgrass in the Great Plains of the United States form an ideal system for this type of study. The crux of this proposal is a relatively large-scale field experiment that is designed to alter the ability of planthoppers and wasps to move among patches (i.e., patch connectivity) by embedding cordgrass patches in either of two dominant matrix types (mudflat or the exotic grass species brome). Emigration, immigration, the pattern of spatial spread, and the within-patch distribution of insects will be assessed from the recapture of fluorescent-marked individuals. The experiment also will be carried out over 3 spatial scales and 6 generations to provide information on the effect of the matrix manipulation on parasitism and density fluctuations among patches and over time. Never before has the patch structure and matrix been manipulated in predator-prey population studies in the field. As a complement to this field experiment, trials will also be conducted to determine the behavioral basis for matrix-dependent movement patterns of the planthopper and wasp. Finally, based on information derived in the above studies, a simulation model will be developed with the goal of evaluating the impact of habitat fragmentation and degradation (e.g., changes in the landscape matrix) on the long-term persistence of predator-prey interactions. Results from this renewal of NSF grant DEB-9973789 should provide critical and much needed information on the effects of heterogeneous landscapes on predator-prey interactions, and hopefully catalyze a broader approach to studies of predator-prey interactions. This research also has broad ramifications for conservation programs that are interested in the connectivity of reserves: a matrix that facilitates dispersal (i.e., a high-quality matrix) may serve a function identical to that of stepping stones or corridors. Finally, this research may have a direct bearing on the success of pest management programs that employ strategies that purposely modify the matrix (e.g., through inter-cropping, terracing, or leaving some fields fallow). Knowledge of the effect of these changes on pest and natural enemy movement and interactions may be critical to developing a successful pest-control program.