International Research Fellowship Program: Impacts of Invasive Ants on Plant Conservation in Mauritius

[40:17 . 03]国际研究奖学金计划使美国科学家和工程师能够到国外进行3至24个月的研究。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持Lori Lach博士与John R. Mauremootoo博士在毛里求斯拉普勒内塞的毛里求斯野生动物基金会（Mauritius Wildlife Foundation）进行为期19个月的研究，并在伊利诺伊大学香槟分校（University of Illinois, champaigne - urbana）与dr。梅·贝伦鲍姆和安德鲁·苏亚雷斯三个月。本项目的部分支持来自环境中的生物复杂性计划。有几种蚂蚁被认为是世界上最具破坏性的入侵物种。入侵蚂蚁对本地蚂蚁和其他节肢动物的影响已得到较好的记录；人们对它们对植物的影响知之甚少。入侵蚂蚁可能依靠花或花外花蜜，或同翅目昆虫的分泌物来维持它们庞大的种群。如果蚂蚁所照料的同翅目植物达到较高的密度，寄主植物的适应性可能会下降，但蚂蚁访问蜜腺或同翅目植物可能会阻止食草动物，从而有利于植物。几种最严重的入侵蚂蚁在热带岛国毛里求斯广泛存在，但它们的生态学从未在这些岛屿上进行过研究。一些恢复的稀有特有植物种群正在爆发同翅目植物，其中一种最普遍的杂草具有花外蜜腺，这表明入侵蚂蚁可能通过多种途径影响岛屿的植物群落。这项研究测试了四个假设：1)入侵蚂蚁在毛里求斯广泛存在，并取代了本土蚂蚁。2)蚂蚁在本地植物上促进同翅目昆虫的爆发，导致植物活力下降。3)入侵蚂蚁在以食物换保护的互惠关系中阻止了食草动物对花外花蜜入侵植物的攻击。4)在蚂蚁繁殖的季节性背景下，蜜露与花蜜和花外花蜜的蛋白质、氨基酸和糖组成存在差异，这影响了蚂蚁从何处获得碳水化合物。通过对8个自然保护区进行季度蚂蚁调查，对同翅目原生植物进行蚂蚁排除实验，对入侵植物Leucaena leucocephala进行蚂蚁排除实验，以及对项目过程中蚂蚁吸收和忽略的花蜜和渗出物进行实验室分析，对假设进行了验证。拟议项目的研究结果将与毛里求斯和其他热带岛屿的保护生物学家以及日益增长的入侵生态学领域有关。这是毛里求斯第一次对蚂蚁进行生态学研究，也是为数不多的评估入侵蚂蚁对非农业热带生态系统植物影响的研究之一，这是第一次比较不同季节群落中蚂蚁对分泌物和花蜜资源的吸引力和组成的研究。

0401703LachThe International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-two-month research fellowship by Dr. Lori Lach to work with Dr. John R. Mauremootoo at the Mauritius Wildlife Foundation in LaPreneuse, Mauritius, for nineteen months and at the University of Illinois, Champaign-Urbana with Drs. May Berenbaum and Andrew Suarez for three months. Partial support for this project comes from the Biocomplexity in the Environment (BE) Program.Several species of ants are considered to be among the world's most destructive invasive species. Impacts of invasive ants on native ants and other arthropods are relatively well-documented; less is known about their impacts on plants. Invasive ants may rely on floral or extrafloral nectar, or homopteran exudates to fuel their large colonies. Host plant fitness may decline if Homoptera tended by ants reach high densities, however ants visiting nectaries or Homoptera may deter herbivores to the benefit of the plant. Several of the worst invasive ants are widespread in the tropical island nation of Mauritius, but their ecology has never been researched on these islands. Several restored populations of rare endemic plants are hosting Homoptera outbreaks, and one of the most widespread weeds has extrafloral nectaries, suggesting that there are multiple avenues through which invasive ants may be affecting the islands' plant communities.This study is testing four hypotheses: 1) Invasive ants are widespread in Mauritius and have displaced native ants. 2) Ants are facilitating Homoptera outbreaks on native plants, and these outbreaks are resulting in decreased plant vigor. 3) Invasive ants are deterring herbivores from extrafloral nectar-bearing invasive plants in a food-for-protection mutualism. 4) There are differences in protein, amino acid, and sugar composition of honeydew and floral and extrafloral nectar that, in the context of the seasonality of ant reproduction, affect where ants obtain carbohydrates. Hypotheses are being tested through 1) quarterly ant surveys of eight nature reserves 2) an ant exclusion experiment on native plants hosting Homoptera, 3) an ant exclusion experiment on the invasive plant Leucaena leucocephala and 4) laboratory analyses of nectars and exudates imbibed and ignored by ants over the course of the project. Findings from the proposed project will be relevant to conservation biologists in Mauritius and other tropical islands as well as to the growing field of invasion ecology. In addition to being the first ecological study of ants in Mauritius, and one of only a handful of studies to assess the impacts of invasive ants on plants in a non-agricultural tropical ecosystem, this is the first study to compare ant attraction to and composition of exudates and nectar resources across a community over different seasons.