生物多样性 ›› 2017, Vol. 25 ›› Issue (12): 1276-1284.DOI: 10.17520/biods.2017301

• 生物入侵专题 • 上一篇    下一篇

养分影响入侵种喜旱莲子草对专食性天敌的防御

周方, 张致杰, 刘木, 潘晓云*()   

  1. 复旦大学生物多样性科学研究所, 生物多样性与生态工程教育部重点实验室, 上海 200438
  • 收稿日期:2017-11-09 接受日期:2017-12-26 出版日期:2017-12-20 发布日期:2017-12-10
  • 通讯作者: 潘晓云
  • 基金资助:
    国家自然科学基金(31370433, 31070369)

Effects of nutrient levels on defense against specialist insects in an invasive alligator weed

Fang Zhou, Zhijie Zhang, Mu Liu, Xiaoyun Pan*()   

  1. Institute of Biodiversity Science, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Fudan University, Shanghai 200438
  • Received:2017-11-09 Accepted:2017-12-26 Online:2017-12-20 Published:2017-12-10
  • Contact: Pan Xiaoyun

摘要:

竞争力增强进化假说(Evolution of Increased Competitive Ability, EICA)认为入侵植物在入侵地由于天敌逃逸导致对天敌防御投入降低而增加生长和繁殖等投入。然而, EICA假说所预测防御能力的进化主要集中在防御的组成抗性方面, 而从诱导抗性和耐受性的角度进行的验证还很有限, 并且忽视了生境资源可利用性对植物防御策略的影响。本研究采用同质园实验比较了喜旱莲子草(Alternanthera philoxeroides)原产地(阿根廷)和入侵地(美国)各9个种群, 在高、低养分和有、无专食性天敌取食处理下的防御相关功能性状(比茎长、根冠比)及其对天敌取食的诱导反应, 以及它们与植物适合度相关指标的关系。结果表明: 入侵地种群具有较高的总生物量(+14.7%)、较低的比茎长(防御钻茎化蛹天敌的重要指标, -27.5%), 暗示其个体大小增加而防御投入降低, 符合EICA假说的预测。入侵地种群耐受性与原产地种群没有显著差异。在高养分下, 入侵地种群的比茎长对专食性天敌取食的诱导反应显著增加, 且与总生物量呈显著正相关。这些结果表明, 相比原产地种群, 入侵地种群具有更高的生物量, 对专食性天敌的组成抗性降低, 且在高养分下对专食性天敌的诱导抗性增加, 推测生境的养分富集可能会降低喜旱莲子草的生物防治效果。

关键词: 竞争力增强进化假说, 植物-昆虫关系, 可塑性, 资源可利用性, 诱导抗性

Abstract

Evolution of Increased Competitive Ability (EICA) has suggested that exotic plants may reduce resource allocation to anti-herbivore defenses and increase allocation to growth due to reduced specialist herbivores in introduced ranges. However, the major limitation for the hypothesis may be that, as important defensive strategies, induced resistance and tolerance were seldom tested and little information is known regarding the evolution of defensive strategies as influenced by resource availability. Nine introduced and nine native populations of Alternanthera philoxeroides were compared for fitness and two morphological traits that influence herbivory, specifically specific stem length (SSL, plants with low SSL have hollow stems favoured by a stem-boring specialist insect Agasicles hygrophila) and root/shoot ratio (RSR) under low and high nutrient availability and with or without A. hygrophila. Introduced populations showed greater total biomass (+14.7%) and lower SSL (-27.5%), demonstrating increased growth and decreased levels of constitutive defense. Tolerance to herbivory was similar between introduced and native populations. SSL plasticity to herbivory was greater in introduced populations under high nutrient levels, and was positively correlated with total biomass. These results suggest that although both functional trait values and plasticity contribute to the adaptation of alligator weeds to a wide range of nutrient availabilities and specialist insect herbivory, introduced populations have evolved higher production of biomass, lower levels of constitutive structural defense, and greater plasticity of structural defense in high nutrient conditions, indicating that the present control practice for A. philoxeroides where introducing A. hygrophila will face great challenges in the future.

Key words: EICA, plant-insect interactions, plasticity, resource availability, induced resistance