Dissertation Research: Impact of Environment on Plant Susceptibility to Leaf-Cutter Ants

拟议的研究调查了环境条件对叶片质量的影响以及切叶蚂蚁随后的选择。切叶蚂蚁是哥斯达黎加La Selva生物保护区的一种主要草食动物。具体地说，将研究光和土壤营养条件的相互作用，以确定植物的敏感性是否通过植物特征的变化而改变。将使用在不同环境条件下生长的田间采集植物和栽培苗木(从单一亲本树的种子开始，以控制遗传效应)的叶子。本研究以热带豆科植物Inga edulis var为研究对象。因为它通常出现在一系列栖息地，所以它似乎会随着不同的环境条件而发生质量变化，并经历Atta攻击。田间采摘和插穗生物检测、实验室选择检测和真菌抑制检测将决定叶片对ATTA的接受性和适合性。相关分析和实验将被用来分离特定的叶片性状对蚂蚁/真菌系统的影响。虽然以前的研究主要是定性的和种间的，但这项研究集中在数量种内变异的影响上。由于蚂蚁/真菌系统在田间和实验室都很容易操作，它提供了一个独特的机会来量化不同环境诱导的叶片性状的影响，并建立切叶蚂蚁选择性背后的机制。

The proposed studies investigate the impact of environmental conditions on leaf quality and subsequent selection by leaf- cutter ants, Atta cephalotes, a dominant herbivore at the La Selva Biological Reserve in Costa Rica. Specifically the interactions of light and soil nutrient conditions will be studied to see if plant susceptibility is altered via changes in plant traits. Leaves from both field collected plants and cultivated seedlings (started from the seeds of a single parent tree, so as to control for genotypic effects) growing under different environmental conditions will be used. This study focuses on a tropical legume species, Inga edulis var. minitula, because it commonly occurs in a range of habitats, appears to change in quality in response to different environmental conditions, and experiences Atta attack. Field pickup and cutting bioassays, laboratory choice assays, and fungal inhibition assays will determine leaf acceptability and suitability to Atta. Both correlative analyses and experiments will be used to isolate the impact of specific leaf traits on the ant/fungus system. While previous research has been largely qualitative and interspecific, this study concentrates on the impact of quantitative intraspecific variation. Since the ant/fungus system is easily manipulated both in the field and in the laboratory, it offers a unique opportunity to quantify the effects of different environmentally induced leaf traits and to establish the mechanism behind leaf-cutter ant selectivity.