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

已经确定，橡树和其他树种一样，由于受到舞毒蛾（GM）毛虫的攻击，叶子质量会发生变化。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，降低了因疾病造成的死亡率。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，因此很难确定树木响应的净效应可能是什么。关于落叶引起的叶片质量变化的研究从未超过2或3年。由于转基因爆发每9年或10年发生一次，这些短期研究几乎不能告诉我们树木对种群波动总体格局的反应的重要性。如果我们要了解树木的作用，建立叶片质量改变的时期以及落叶下降后持续多久的变化是至关重要的。这是短期学习无法做到的。转基因爆发还必须改变同一森林中其他食草动物可获得的叶子的质量和数量。在爆发期间，有记录的叶片化学变化和立叶作物的急剧减少必然会在转基因作物和其他物种之间产生相互作用——可能是负面的，也可能是竞争的。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通过改变宿主植物的质量可能对另一种食草动物产生微妙但重要的影响。很明显，疫情提供了一个机会来量化一种食草动物（例如转基因动物）对另一种食草动物的影响，但这还没有做到；这种类型的“之前、期间和之后”研究从未出现过。该项目是一项长期（10-20年）研究计划的前5年，旨在解决这两个主要的生态问题。在宾夕法尼亚州中部一个典型的舞毒蛾侵染地点对落叶引起的橡树叶化学变化进行了一系列具体研究，在宾夕法尼亚州中部舞毒蛾侵染地点进行了三年的数据研究，在舞毒蛾侵染地点进行了三年的数据研究，并对舞毒蛾种群和橡树叶性状进行了三年的数据研究。已经积累起来了。最重要的性状是酚类物质，特别是可水解单宁，和氧化能力（如酚氧化酶和过氧化物酶活性）。这些成分在不同的树木之间差异很大，影响舞毒蛾及其疾病，至少酚类成分会因落叶而改变。将通过两次转基因爆发监测3种栎树的关键叶片特征，根据测量的昆虫种群密度和落叶水平建立树木反应模式。通过跟踪感染水平与昆虫密度、落叶和树叶性状的关系，将评估转基因群体中叶片性状与病毒流行之间的关系。同时，还将研究转基因种群对其他草食性昆虫可能产生的影响，通过对在焦点橡树和非寄主红枫上共存的草食性昆虫进行调查。非转基因草食动物的密度将与转基因密度、落叶水平和树叶性状统计相关。尽管长期监测工作是该项目的核心，但数据收集的目的是从一开始到整个研究过程中检验特定的假设。通过开展这一长期项目，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在森林系统中发生或常见。​K MK MF m m ？荷兰（可伸缩）R符号“瑞士（可伸缩）1 Courier”h _ _ h；伊丽莎白·m·贝伦斯

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