REU: Effects of Elevated Atmospheric Carbon Dioxide on Plant-Insect Interactions

全球大气中的二氧化碳水平正在上升，到21世纪下半叶，目前的水平可能会翻一番。众所周知，二氧化碳浓度升高会改变植物的生理和生长，但很少有研究解决二氧化碳浓度升高对植物生态相互作用的影响。一些研究已经记录了二氧化碳对草本植物和昆虫之间相互作用的显著影响，但对二氧化碳对树木和以树为食的昆虫之间相互作用的影响一无所知。本研究的目的是探讨富CO2大气在树木化学成分变化的介导下对落叶树与取食昆虫相互作用的影响。该模型系统将由颤杨、红橡树和枫树（分别为快速、中、慢生长物种）和两种食叶昆虫，舞毒蛾和森林帐篷毛虫组成。资源可用性理论被用作三个主要目标和相关假设发展的框架。本研究的三个目标是：1)确定CO2浓度升高对树木化学成分的影响，以及对昆虫性能（生存、生长、食物利用效率）的影响；2)研究CO2浓度升高和土壤养分有效性对树木化学成分和昆虫性能的交互影响；3)测定CO2浓度升高和落叶对树木化学成分和昆虫生长性能的交互作用。这些树木将在威斯康星大学Biotron的环境控制室中，在不同浓度的二氧化碳下生长，并进行化学和生物分析。本研究的显著特点包括：重点研究CO2对森林树木及其脱叶动物相互作用的介导效应，重点研究CO2对植物化学成分的影响，重点研究CO2及其环境“应力”对植物-昆虫相互作用的相互作用。以及利用北美落叶林中在生态和经济上重要组成部分的三种树种和两种昆虫。

Global atmospheric CO2 levels are rising, and current levels may double by the latter half of the 21st century. Elevated CO2 is known to alter plant physiology and growth, but very little research has addressed the consequences of elevated CO2 for the ecological interactions of plants. A couple of studies have documented significant effects of CO2 on interactions between herbaceous plants and insects, but nothing is known about effects of CO2 on interactions between trees and tree-feeding insects. The purpose of this research is to investigate the effects of enriched CO2 atmospheres on interactions between deciduous trees and tree-feeding insects, as mediated by changes in tree chemical composition. The model system will consist of quaking aspen, red oak and maple (fast-, intermediate- slow-growing species, respectively) and two leaf- feeding insects, the gypsy moth and forest tent caterpillar. Resource availability theory is used as a framework for development of three primary goals and associated hypotheses. The three goals of this research are to: 1) determine the effects of elevated CO2 on tree chemical composition, and consequences for performance (survival, growth, food use efficiencies) of insects, 2) investigate the interactive effects of elevated CO2 and soil nutrient availability on tree chemical composition and insect performance, and 3) determine the interactive effects of elevated CO2 and defoliation on tree chemical composition and insect performance. Trees will be grown under several concentrations of CO2 in environmental control rooms at the University of Wisconsin Biotron, and subjected to chemical assays and bioassays. Significant features of this research include its focus on CO2-mediated effects on interactions between forest trees and their defoliators, an emphasis on effects of CO2 on plant chemical composition, an emphasis on interactive effects between CO2 and their environmental "stresses" on plant-insect interactions, and use of three tree species and two insect species that are ecologically and economically important components of North American deciduous forest.