Allee effects and population regulation: a test for biotic resistance against an invasive leafroller by resident parasitoids
Allee effects and population regulation: a test for biotic resistance against an invasive leafroller by resident parasitoids
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DOI：
10.1007/s10144-014-0451-4
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发表时间：
2015-01-01
影响因子：
1.7
通讯作者：
Mills, Nicholas J.
中科院分区：
文献类型：
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作者：
Buergi, Linda P.;Roltsch, William J.;Mills, Nicholas J.
常驻天敌可以通过引起阿利效应来影响入侵物种，从而导致小型创始种群的建立成功率降低，或者通过调节或仅仅抑制已建立种群的丰度。 Epiphyas postvittana，即浅棕色苹果蛾，是加利福尼亚州的一种入侵卷叶蛾，被发现受到一大群常驻寄生蜂的攻击，导致寄生率相对较高。在四年的时间里，我们测量了加利福尼亚州四个 E. postvittana 种群的丰度和人均增长率，并确定了寄生率。我们发现，在其中两个地点，寄生引起了阿利效应，即在较低的 E. postvittana 种群密度下个体存活率降低，尽管它没有转化为人口阿利效应，即对低密度下人均人口增长率的影响。相反，所有四个地点的 E. postvittana 种群在每个地点观察到的整个密度范围内都表现出强烈的补偿密度反馈。由于我们没有发现人均人口增长率与寄生率之间存在负相关关系的证据，因此我们得出结论，寄生蜂无法调节加利福尼亚州的 E. postvittana 种群。尽管缺乏监管或人口 Allee 效应的证据，但寄生蜂对 E. postvittana 种群的影响是巨大的，并且表现出对这种新入侵者的显着生物抗性。
Resident natural enemies can impact invasive species by causing Allee effects, leading to a reduction in establishment success of small founder populations, or by regulating or merely suppressing the abundance of established populations. Epiphyas postvittana, the Light Brown Apple Moth, an invasive leafroller in California, has been found to be attacked by a large assemblage of resident parasitoids that cause relatively high rates of parasitism. Over a 4-year period, we measured the abundance and per capita growth rates of four E. postvittana populations in California and determined parasitism rates. We found that at two of the sites, parasitism caused a component Allee effect, a reduction in individual survivorship at lower E. postvittana population densities, although it did not translate into a demographic Allee effect, an impact on per capita population growth rates at low densities. Instead, E. postvittana populations at all four sites exhibited strong compensatory density feedback throughout the entire range of densities observed at each site. As we found no evidence for a negative relationship between per capita population growth rates and parasitism rates, we concluded that resident parasitoids were unable to regulate E. postvittana populations in California. Despite a lack of evidence for regulation or a demographic Allee effect, the impact of resident parasitoids on E. postvittana populations is substantial and demonstrates significant biotic resistance against this new invader.