The Roles of Stress and Time in Insect Outbreaks: The Effect of a One Million-Year Successional Gradient and a 100-Year Regional Drought on the Pinyon Needle Scale

这个项目研究了非生物胁迫在解释Keystone昆虫食草动物暴发的局部和区域模式方面的潜在作用，表现在土壤发育的100万年连续梯度和100年创纪录的干旱中。首先，研究人员假设，在相同的气候制度下，从年轻的火山土壤到古老的火山土壤，规模食草性将在100万年的演替梯度上减少。其次，他们假设，新的大规模疫情是对干旱脉冲的反应而产生的，规模人口比遭受长期攻击的高压力地点更不稳定。松针鳞的新暴发和慢性侵扰的结合为一系列实验提供了基础，这些实验旨在增加我们对促进和维持昆虫暴发的因素的了解。这些因素将通过密集的人口研究，比较早期暴发和慢性感染，以及土壤和植物的相互移植实验来检验。这些研究是将一百万年的演替梯度、慢性应激和急性应激事件结合起来解释暴发物种的空间和时间动态的关键机会，这种暴发物种在最近的一次干旱期间扩大成为一个区域问题。

0075563WhithamThis project examines the underlying role of abiotic stress, as expressed in a one million-year successional gradient of soil development and a 100-year record drought, in explaining local and regional patterns of outbreaks in a keystone insect herbivore. First, the investigators hypothesize that scale herbivory will decrease across a one million-year successional gradient of young to old volcanic soils under the same climatic regime. Second, they hypothesize that new scale outbreaks are created in response to pulse of drought and that scale populations are less stable than high stress sites that suffer chronic attack. The combination of both new outbreaks and chronic infestations of pinyon needle scale provides the basis for a series of experiments that are designed to increase our understanding of the factors that promote and maintain insect outbreaks. These factors will be examined through intensive population studies comparing incipient outbreaks and chronic infestations, as well as reciprocal transplant experiments of soils and plants. These studies represent a critical opportunity to integrate a million-year successional gradient, chronic stress and acute stress events to explain spatial and temporal dynamics of an outbreak species that has expanded during a recent drought to become a regional problem.