LTREB: Long-Term Studies of a Gypsy Moth-Impacted Forest

小行星9318073 已经确定，橡树，像其他树种一样，由于受到舞毒蛾（GM）毛虫的攻击，叶片质量发生了变化。 这些变化对转基因至少有两个重要影响：它们降低了繁殖力，降低了疾病造成的死亡率。 任何一种效应都可能影响转基因（和其他昆虫）的种群动态，但由于它们的影响似乎是相反的，很难确定树木反应的净效应可能是什么。 没有研究落叶引起的叶片质量的变化已经超过2或3年。 由于转基因作物每隔9年或10年爆发一次，这些短期研究无法告诉我们树木对种群波动总体模式的反应的重要性。 如果我们要了解树木的作用，关键是要确定叶片质量发生变化的时间，以及落叶减少后变化持续多久。 这是短期研究无法做到的。 转基因的爆发也必然会改变同一森林中其他食草动物可获得的树叶的质量和数量。 有记录的叶片化学变化和爆发期间叶片现存量的急剧减少必然会在转基因和其他物种之间产生相互作用-可能是负面的，或竞争性的。 在过去的20年里，生态学文献一直被这样一种观点所主导，即食草昆虫之间不太可能发生这种食物介导的相互作用。 最近，研究人员开始意识到一种食草动物可能通过改变宿主植物的质量而对另一种食草动物产生微妙但重要的影响。 很明显，爆发提供了一个机会来量化一种食草动物的影响（例如，全球机制）对其他人的影响，但这一点尚未做到;从来没有进行过这类“之前、期间和之后”的研究。 本项目是针对这两个主要生态问题的长期（10-20年）研究计划的前5年。 在宾夕法尼亚州中部一个典型的舞毒蛾影响地点的落叶引起的橡树叶化学变化的一系列具体研究中，宾夕法尼亚州中部舞毒蛾影响地点的三年爆发后数据，三年爆发后舞毒蛾种群和橡树叶性状的数据。已经积累起来了。 最重要的特性是酚类物质，特别是可水解的单宁，和氧化能力（例如，酚氧化酶和过氧化物酶活性）。 这些在树木之间变化很大，影响舞毒蛾及其疾病，至少酚类成分被落叶改变。 通过两次转基因疫情监测3个橡树品种的大样本的关键叶性状，建立树木的响应模式与测量的昆虫种群密度和落叶水平。 将通过跟踪与昆虫密度、落叶和树叶特征有关的感染水平，评估转基因种群中树叶特征与病毒流行之间的关系。 与此同时，转基因种群对其他草食性昆虫的可能影响将被调查，通过谴责那些共存于焦点橡树和一个非宿主红枫。 非转基因食草动物的密度在统计上与转基因密度、落叶水平和树叶特征有关。 虽然长期监测工作是该计划的核心，但数据收集的目的是从一开始就测试特定的假设，并贯穿整个研究。 通过开展这项长期计划，将首次确定诱导的植物反应是否具有生态意义，以及食草昆虫之间的负面相互作用是否发生或在森林系统中是否常见。 K M K M F M M ? 荷兰语（scalable）R符号“Swiss（scalable）1 C " H _ _ H ; 伊丽莎白·M伊丽莎白·M. Behrens

9318073 Schultz It has been established that oaks, like other tree species, experience altered leaf quality as a consequence of being attacked by gypsy moth (GM) caterpillars. These changes have at least two important effects on the GM: they reduce fecundity and decrease mortality due to disease. Either effect could influence population dynamics of GM (and other insects), but because their influences appear to be opposite, it is difficult to determine what the net effect of tree responses might be. No study of defoliation-induced changes in leaf quality has ever extended beyond 2 or 3 years. Since GM outbreaks recur every 9 or 10 years, these short-term studies can tell us little about the importance of tree responses to the overall pattern of population fluctuation. It is critical to establish the period over which leaf quality is altered, and how long changes last after defoliation has declined if we are to understand the role of the tree. This cannot be done with short-term studies. GM outbreaks must also alter the quality and quantity of leaves available to other herbivores in the same forest. Documented changes in leaf chemistry and the dramatic reduction in leaf standing crop during an outbreak must produce interactions - probably negative, or competitive - between the GM and other species. For the past 20 years, the ecological literature has been dominated by the view that such food-mediated interactions among herbivorous insects were unlikely. More recently, researchers have begun to appreciate the subtle, but significant, impact one herbivore may have another by altering host plant quality. It i s obvious that outbreaks provide an opportunity to quantify the impact of one herbivore (e.g., the GM) on other, yet this has not been done; there has never been a "before, during, and after" study of this type. This project addresses the first 5 years of a long-term (10-20 years) research program aimed at addressing these two major ecological problems. In a series of specific studies of defoliation-induced changes in oak leaf chemistry at a typical gypsy moth-impacted site in central Pennsylvania, three years of post-outbreak data on gypsy moth-impacted site in central Pennsylvania, three years of post-outbreak data on gypsy moth populations and oak leaf traits. have been accumulated. The traits of greatest importance are phenolics, especially hydrolyzable tannins, and oxidative capacity (e.g., phenoloxidase and peroxidase enzyme activity). These vary dramatically among trees, influence the gypsy moth and its diseases, and at least the phenolic constituents are altered by defoliation. Critical leaf traits of a large sample of 3 oak species will be monitored through two GM outbreaks, establishing the pattern of tree response in relation to measured insect population densities and defoliation levels. The relationship between leaf traits and virus prevalence in GM populations will be assessed by tracking infection levels in relation to insect density, defoliation, and tree leaf traits. At the same time, the possible impact of GM populations on other herbivorous insect will be investigated, by censuring those coexisting on the focal oaks and one non-host, red maple. Densities of non-GM herbivores will be related statistically to GM density, defoliation levels, and tree leaf traits. Although a long-term monitoring effort is the core of this program, the data-gathering is designed to test specific hypotheses right from the start and throughout the study. BY undertaking this long term program, for the first time it will be determined whether induced plant responses can be ecologically mea ningful, and whether negative interactions among herbivorous insects occur or are common in forested systems. K M K M F M M ? Dutch (scalable) R Symbol " Swiss (scalable) 1 Courier " h _ _ H ; Elizabeth M. Behrens Elizabeth M. Behrens