Efficacy of tree defense physiology varies with bark beetle population density: a basis for positive feedback in eruptive species
Efficacy of tree defense physiology varies with bark beetle population density: a basis for positive feedback in eruptive species
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DOI：
10.1139/x11-041
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发表时间：
2011-06-01
影响因子：
2.2
通讯作者：
Raffa, Kenneth F.
中科院分区：
文献类型：
--
作者：
Boone, Celia K.;Aukema, Brian H.;Raffa, Kenneth F.
我们评估了组成型和诱导型防御系统保护树木和限制食草动物繁殖的能力，短暂的），和爆发阶段的本地树皮甲虫物种。宿主防御的主要限制时，山松甲虫（Dendroctonus ponderosae霍普金斯）人口低，但无关紧要的林分水平密度超过一个临界阈值后。我们每年检查所有的lodgepole松（松contorta道格拉斯变种。latifolia）在6个12-18公顷的林分中，随着甲虫密度在各个种群阶段的进展，甲虫攻击和建立的时间为3-6年。我们还分析了一套树木的生理和化学属性，并将它们与当年的后续攻击联系起来。快速诱导防御比组成性防御更重要，总单萜比特定成分更重要。树木分泌更多的树脂和积累更高的单萜浓度在模拟攻击很大程度上逃避自然的攻击时，人口低。在甲虫已经达到初始密度的林分中，这些防御是无效的。直径较大的树木比直径较小的树木有更明显的防御。随着种群数量的增加，甲虫会选择更大、资源更丰富的树木，尽管它们的防御能力更强。当种群太低，合作攻击，甲虫利用树木削弱了较低的茎昆虫。行为可塑性使甲虫能够在地方性水平上持续存在，直到条件发生变化，之后正反馈占主导地位。
We evaluated the ability of constitutive and inducible defenses to protect trees and restrict herbivore reproduction across the endemic, incipient (i.e., transitory), and eruptive phases of a native bark beetle species. Host defenses were major constraints when mountain pine beetle (Dendroctonus ponderosae Hopkins) populations were low, but inconsequential after stand-level densities surpassed a critical threshold. We annually examined all lodgepole pines (Pinus contorta Douglas var. latifolia) in six 12-18 ha stands for 3-6 years for beetle attack and establishment as beetle densities progressed through various population phases. We also assayed a suite of tree physiological and chemical attributes and related them to subsequent attacks during that year. Rapidly inducible defenses appeared more important than constitutive defenses, and total monoterpenes were more important than particular constituents. Trees that exude more resin and accumulate higher monoterpene concentrations in response to simulated attack largely escaped natural attacks when populations were low. In stands where beetles had reached incipient densities, these defenses were ineffective. Larger diameter trees had more pronounced defenses than smaller diameter trees. As populations increased, beetles selected increasingly larger, more resource-rich trees, despite their better defenses. When populations were too low for cooperative attack, beetles exploited trees weakened by lower-stem insects. Behavioral plasticity allows beetles to persist at endemic levels until conditions shift, after which positive feedbacks predominate.