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

在哥斯达黎加的La Selva生物保护区，研究了环境条件对切叶蚁（Atta cephalotes）叶片质量和随后选择的影响。切叶蚁是一种优势食草动物。具体而言，将研究光和土壤养分条件的相互作用，以确定植物的敏感性是否通过植物性状的变化而改变。将使用在不同环境条件下生长的田间采集植物和栽培幼苗（从单株树的种子开始，以控制基因型效应）的叶片。本研究的重点是热带豆科植物Inga edulis var. minitula，因为它通常生长在一系列栖息地，在不同的环境条件下表现出质量变化，并经历Atta攻击。田间采摘和切割生物测定，实验室选择测定和真菌抑制测定将确定叶片的可接受性和Atta的适用性。相关分析和实验将用于分离特定叶片性状对蚂蚁/真菌系统的影响。以往的研究主要集中在定性和种间，而本研究集中在定量种内变异的影响上。由于蚂蚁/真菌系统在田间和实验室中都很容易操作，因此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.