Impacts of polyandry and mate limitation on female fecundity and the population dynamics of the aspen leaf miner

一些物种的种群可以在很长一段时间内保持低数量，然后迅速上升到非常高的数量。当这些物种对人类资源造成损害时，它们的人口“爆炸”就成为一个实际问题。当种群非常小的时候，研究它们通常是困难的，因为个体是如此罕见和难以找到。然而，了解是什么使一个物种保持稀有，以及是什么使种群进入快速增长期，对于预测和控制多种疾病的爆发非常重要。这项研究探讨了白杨树叶虫丰度剧烈循环的可能原因，白杨树叶虫是一种微小的飞蛾，通常很罕见，但可以爆发并对白杨树造成广泛的损害。特别是，研究人员将测试小种群中的雌性是否不能像大种群中的雌性那样频繁交配和产卵。如果得到证实，小种群的低交配成功率可能对控制其他森林害虫和减缓入侵物种的传播很重要。以颤杨（Populus tremuloides）为食的白杨叶螨（Phyllocnistis popululiella）由于其高水平的多夫制和持续的种群低、高阶段，为探索寻偶通道效应对种群大幅波动的潜在人口影响提供了一个很好的系统。该项目将采用实验和观察相结合的方法来解决寻找配偶的Allee效应和一妻多夫制是否有助于维持白杨叶矿工的低阶段。具体来说，它将采用：1)交配实验来检验多次交配是否会增加雌性的繁殖力；2)在不同密度的种群中进行观察性研究，以解决潜在的和已经实现的一妻多夫制是否会随着种群密度的增加而增加。更好地了解将种群保持在低密度或将其释放到生长阶段的机制将有助于预测可能发生疫情的地点和时间。

Populations of some species can persist at low numbers for long periods of time and then quickly rise to very high numbers. When these species inflict damage on human resources, their population "explosions" become a practical concern. It is often difficult to study populations when they are very small because individuals are so rare and hard to find. Yet, understanding what keeps a species rare and what happens to shift populations into periods of rapid growth is important for predicting and controlling outbreaks of many kinds. This research examines possible reasons for dramatic cycles of abundance in the aspen leaf miner, a tiny species of moth that is usually rare but can outbreak and cause extensive damage to aspen trees. In particular, investigators will test whether females in small populations are unable to mate as often and lay as many eggs as females in large populations. If confirmed, low mating success in small populations may be important in controlling other forest pests and slowing the spread of invasive species. Due to its high level of polyandry and sustained low and high population phases, the aspen leaf miner (Phyllocnistis populiella) feeding on quaking aspen (Populus tremuloides) provides an excellent system for exploring potential demographic impacts of mate-finding Allee effects on large amplitude population fluctuations. This project will use a combination of experimental and observational approaches to address whether mate-finding Allee effects and polyandry contribute to sustaining low phases of the aspen leaf miner. Specifically it will employ: 1) mating experiments to examine whether multiple mating increases female fecundity, and 2) observational studies across populations with varying densities to address whether potential and realized polyandry increases with population density. A better understanding of the mechanisms keeping populations at low density or releasing them into growth phases will aid predictions of where and when outbreaks are likely to occur.