Monarch fall migration, overwintering mortality and the effects of defence compounds released by decomposing butterflies on the soil ecosystem.

帝王蝶秋季迁徙、越冬死亡率以及分解蝴蝶释放的防御化合物对土壤生态系统的影响。

• 批准号: RGPIN-2020-07203
• 负责人: McNeil, Jeremy
• 金额: $ 2.4万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=718543
• 关键词: Monarch; fall; migration; overwintering; mortality

North American populations of the monarch, an iconic insect known for its migration to and from overwintering sites in Mexico, have declined due to a number of factors including habitat loss and modern agricultural practices. Habit loss due to illegal logging has declined and conservation programmes have resulted in increased availability of milkweed, the only host plant used by the monarch. However, other aspects that could help conservation efforts have received less attention. Adult monarchs migrating to Mexico are sexually immature and need nectar sources to sustain themselves during migration, and to accumulate sufficient fat reserves to survive winter, yet we do not detailed information of fat acquisition and use during this important period. Our hypothesis is that in fall the migrating adults sustain just enough reserves for flight and maintenance by feeding daily on local nectar sources and only markedly increase fat reserves once they are very close to the overwintering site. To test this, we will monitor the fat content of monarchs at different sites along the migratory corridor in Canada, USA and Mexico with those arriving at overwintering sites. We will also monitor temporal patterns of mortality during the winter to determine the relative importance of fat reserves on survival, compared with factors such as natal origin and parasite load. This study will be run over five years as the inter-year availability of nectar resources will vary with climatic conditions. For example, due to the warm summer in 2019, at the end of August early emerging adults in Ontario started reproducing rather than emigrating. If the offspring successfully complete development, adults will emerge when very few nectar sources are available, and thus would not have the necessary resources to successfully migrate. Similarly, there are far fewer flowers available this year in Mexico due to drought, so immigrants will have less opportunity to build up the reserves required to survive the winter, which is critical as few nectar resources exist at the overwintering sites. As adverse weather conditions at any point along the migratory corridor could negatively affect resource availability the results of our research will help develop management strategies that ensure nectar sources are available along the migratory route, ensuring greater survival both while migrating and during the winter. Currently, one unanswered basic question is “how do monarchs, even though they have never been there before, locate the same overwintering sites year after year?” Many monarchs die during the winter and so we are undertaking studies to determine if the release of chemicals from decomposing individuals, which live monarchs use in defend against predators, impacts the soil ecosystem and that these changes result in the production of chemical signals that the immigrating butterflies use to locate overwintering sites.

帝王是一种标志性的昆虫，以迁徙到墨西哥越冬地而闻名。由于栖息地丧失和现代农业实践等一系列因素，帝王在北美的数量有所下降。由于非法砍伐导致的习性丧失已经减少，保护计划导致了马利筋的可获得性增加，马利筋是君主使用的唯一寄主植物。然而，其他可能有助于保护工作的方面却没有得到太多关注。迁徙到墨西哥的成年帝王是性不成熟的，在迁徙期间需要花蜜来源来维持自己，并积累足够的脂肪储备以度过冬天，但我们没有这一重要时期脂肪获取和使用的详细信息。我们的假设是，在秋天，迁徙的成虫通过每天吃当地的花蜜来源来维持足够的飞行和维持储备，只有当它们非常接近越冬地点时，才会显着增加脂肪储备。为了测试这一点，我们将监测加拿大、美国和墨西哥迁徙走廊沿线不同地点的帝王鸟的脂肪含量，以及到达越冬地点的帝王鸟的脂肪含量。我们还将监测冬季死亡率的时间模式，以确定脂肪储备对生存的相对重要性，并与出生来源和寄生虫负载等因素进行比较。这项研究将持续五年，因为花蜜资源的年际可获得性将随着气候条件的不同而不同。例如，由于2019年夏天温暖，8月底，安大略省的初出茅庐的成年人开始繁殖，而不是移民。如果后代成功完成发育，成虫将在几乎没有花蜜来源的情况下出现，因此没有必要的资源来成功迁徙。同样，由于干旱，墨西哥今年可用的花卉要少得多，所以移民建立过冬所需的花卉储备的机会将更少，这一点至关重要，因为越冬地点几乎没有花蜜资源。由于迁徙走廊沿线任何地点的不利天气条件都可能对资源的可用性产生负面影响，我们的研究结果将有助于制定管理策略，确保沿迁徙路线提供花蜜来源，确保在迁徙期间和冬季都有更大的存活率。 目前，一个悬而未决的基本问题是：尽管帝王们以前从未去过那里，但它们如何年复一年地找到相同的越冬地点？许多帝王在冬天死亡，因此我们正在进行研究，以确定腐烂的个体释放的化学物质是否会影响土壤生态系统，以及这些变化是否会导致迁徙的蝴蝶用来定位越冬地点的化学信号。