Dissertation Research:Phenotypic Selection on the Timing of Life History Events in Psilocorsis quercicella (Lepidoptera: Oecophoridae) Resulting from Multi-Trophic Interactions

9700887 Marquis The PIs的研究将探索食物质量和寄生虫攻击这两种力量如何作为选择性力量，影响以橡树为食的毛虫种群的发育时间变异模式。因此，这项研究有助于实现种群生物学的基本目标，阐明塑造生物种群内变异模式的生态和选择性力量。PI的研究很重要，因为很少有研究研究多种力量如何相互作用，在自然人口中产生这样的模式。在我们研究的种群中，毛虫在何时开始觅食以及完成发育需要多长时间方面存在相当大的差异。以低质量树叶为食的毛虫可能需要更长的时间才能完成发育，这增加了它们受到天敌攻击的风险。天敌是寄生蜂，它们的后代以毛虫的身体为食，最终杀死它。此外，毛毛虫被攻击的风险取决于它生长季节的时间。通过控制这两个因素(取食的时间和毛虫取食的叶子的质量)，将确定每一个因素与寄生率之间的关系。这项研究的结果将有助于我们理解生态力量如何相互作用来影响昆虫食草动物生命周期的时间。通过记录在不同时间或不同持续时间取食的相关后果，这项研究将提供重要证据，证明植物质量和寄生作为影响自然草食动物种群的两种生物力量的相对重要性。特别是，这项研究将是第一批证明寄生蜂是影响毛虫种群生活史事件发生时间的重要选择力量之一。此外，由于这些寄生蜂是重要的经济害虫的重要选择力量，这项研究将提供与长期生物防治计划成功相关的数据。这类计划是为了控制以农产品为食的重要经济害虫的暴发。与相对简单的农业系统相比，自然系统高度复杂，往往涉及多种寄生虫攻击一种食草动物，从而降低了暴发的可能性。因此，了解食草动物的自然种群如何受到寄生虫的有效调控，对于控制高度管理的农业生态系统的努力至关重要。

9700887 Marquis The PIs' research will explore how two forces, food quality and parasite attack, act as selective forces influencing the pattern of variation in development time in a population of oak-feeding caterpillars. As such, this study contributes to a basic goal of population biology, elucidating the ecological and selective forces that shape patterns of variation within populations of organisms. The PIs' research is important because few studies have examined how multiple forces interact to produce such patterns in natural population. Within our study population, caterpillars vary considerable in when they begin feeding and how long it takes them to complete development. Caterpillars that feed on low quality leaves may take longer to complete development, increasing their risk of being attacked by their natural enemies, parasitic wasps whose offspring feed on the body of the caterpillar, eventually killing it. Additionally, a caterpillar's risk of being attacked depends on the time during the season during which it develops. By manipulating these two factors (the timing of feeding and the quality of leaves caterpillars feed on), the relationship between each of these factors and the rate of parasitism will be determined. The results of this study will contribute to our understanding of how ecological forces interact to influence timing in the life cycle of insect herbivores. By documenting the consequences associated with feeding at different times or for different durations, this study will provide important evidence regarding the relative importance of plant quality and parasitism as two biological forces impacting natural herbivore populations. In particular, this study will be one of the first to demonstrate that parasitic wasps represent an important selective force influencing the timing of life cycle events of caterpillar populations. Additionally, since these parasitic wasps represent an important selective force for economically important pests, this study will pr ovide data relevant to the success of long-term biological control programs. Such programs have been developed to control outbreaks of economically important pest insects which feed on agricultural products. In contrast to the relatively simple agricultural systems, natural systems are highly complex, often involving multiple parasite species attacking a single herbivore resulting in a decreased likelihood of outbreak. Understanding how natural populations of herbivores are effectively regulated by their parasites is thus critical to control efforts in highly managed agricultural ecosystems.