Paleoecology of butterfly and moth populations

蝴蝶和蛾种群的古生态学

• 批准号: RGPIN-2021-02753
• 负责人: Cwynar, Les
• 金额: $ 2.19万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=742199
• 关键词: Paleoecology; butterfly; moth; populations

Eastern spruce budworm (SBW) is a major disturbance agent of eastern North American forests, reaching epidemic proportions on a 25-40 year cycle. These outbreaks can have severe economic impacts; the SBW outbreak of 1967-1993 affected 50 M hectares of forest in eastern North America, with an estimated loss of 44 million m3 of timber per year of the cycle. Economic models indicate potential losses of $10.8 - 15.3 billion in Atlantic Canada during an outbreak. Disturbances are often classified based on their extent, severity, duration, and frequency. As climate warming continues to change landscapes worldwide, researchers are attempting to understand and predict how these aspects of disturbance are likely to change and how those changes may necessitate changes in forest management practices. Understanding the past relationships between moth outbreaks and climate will reveal how outbreaks are expected to change in the future and allow us to adapt appropriate management strategies. Unfortunately, the influence of a changing climate on the frequency, duration and severity of SBW outbreaks is largely unknown, mostly because 1) only two outbreaks have been studied in any detail because of their great length, and 2) the interactions of SBW with its hosts, predators, parasites, and climate are extremely complex and largely unknown. One objective of the proposed research program is to determine how the frequency, duration and severity of SBW outbreaks are related to climate. We will use a novel method to study past moth populations. Moth and butterfly wings are covered by microscopic scales of different shapes and sizes that are made of chitin, which preserves well in lake sediments. I will reconstruct the outbreak history of SBW from lake sediments for two contrasting climate periods -The Medieval Climate Anomaly (also called the Medieval Warm Period), when it was warmer than average, and the Little Ice Age, when it was colder than average. Each of these periods spans about 300 years, so we can expect 8-12 cycles within each. I will statistically compare the frequency, duration, and severity of SBW outbreaks between these contrasting climates, thereby gaining insight into the relationship of SBW population dynamics to climate. Another aspect of my research relates to the monarch butterfly, one of the few charismatic, iconic insects. To great consternation, its populations have been declining for the past 60 years. Why this is happening is an area of active research. But is this decline part of natural cycles? How unusual is this decline? Were populations perhaps smaller in general in pre-European times when there were fewer agricultural/disturbed fields that would support the monarch's host plant, milkweeds? I will core lakes within the main overwintering grounds of the monarch in Mexico where the highest concentrations of monarchs occur and use changes in the abundance of fossil wing scales as an index of past population sizes of monarchs.

东部云杉budworm （SBW）是北美东部森林的主要干扰因子，在25-40年的周期内达到流行程度。这些疫情可造成严重的经济影响；1967-1993年的小蠹虫爆发影响了北美东部5 000万公顷的森林，估计该周期每年损失木材4 400万立方米。经济模型显示，在疫情爆发期间，加拿大大西洋地区的潜在损失为108亿至153亿美元。干扰通常根据其程度、严重程度、持续时间和频率进行分类。随着气候变暖继续改变世界范围内的景观，研究人员正试图了解和预测这些干扰方面可能发生的变化，以及这些变化可能如何导致森林管理实践的改变。了解过去飞蛾爆发与气候之间的关系将揭示未来爆发的预期变化，并使我们能够调整适当的管理策略。不幸的是，气候变化对SBW爆发的频率、持续时间和严重程度的影响在很大程度上是未知的，主要是因为1)由于时间很长，只有两次爆发得到了详细的研究，2)SBW与其宿主、捕食者、寄生虫和气候的相互作用极其复杂，在很大程度上是未知的。拟议研究计划的一个目标是确定SBW爆发的频率、持续时间和严重程度与气候的关系。我们将使用一种新的方法来研究过去的飞蛾种群。飞蛾和蝴蝶的翅膀上覆盖着不同形状和大小的微小鳞片，这些鳞片是由几丁质制成的，在湖泊沉积物中保存得很好。我将从两个不同的气候时期的湖泊沉积物中重建SBW的爆发历史——中世纪气候异常期（也称为中世纪温暖期），当它比平均温度要高，而小冰期，当它比平均温度低。这些周期中的每一个都持续了大约300年，所以我们可以预计在每个周期中有8-12个周期。我将统计比较频率，持续时间，以及这些对比气候之间的SBW爆发的严重程度，从而深入了解SBW种群动态与气候的关系。我研究的另一个方面与帝王蝶有关，它是为数不多的具有魅力的标志性昆虫之一。令人震惊的是，在过去的60年里，它的数量一直在下降。为什么会发生这种情况是一个活跃的研究领域。但这种衰退是自然循环的一部分吗？这种下降有多不寻常？在前欧洲时代，支持黑脉金斑蝶寄主植物乳草的农业/受干扰的土地较少，种群总体上可能更小吗？我将在墨西哥黑脉金斑蝶的主要越冬地内的湖泊中取样，那里是黑脉金斑蝶最集中的地方，并利用化石翅鳞丰度的变化作为过去黑脉金斑蝶种群规模的指标。