Consequences of host plant toxicity across monarch butterfly ontogeny: milkweed challenges from feeding to flying

北美帝王蝶数量的减少与它们在沿着美国和墨西哥迁徙路线上失去了马利筋宿主植物有关。这导致了国家倡议和当地热心人士的重大马利筋重新种植努力。虽然其概念值得称赞，但这些重新种植的努力往往使用各种乳草物种，这些物种对君主幼虫的毒性水平可能会有很大差异。此外，还不知道幼虫暴露于如此不同程度的毒性会如何影响存活的成年帝王蝶建立可生存种群和迁移到墨西哥越冬地点的能力。利用NSF的资金，并利用Monarch科学家的大规模合作网络，研究人员将通过在受控实验室和自然环境下检查Milkweed-Monarch在其整个生活史中的相互作用来量化这些影响。除了帝王蝶，该项目将为栖息地恢复工作提供信息，旨在抵消其他有益昆虫的种群下降，因为大多数昆虫对幼虫饮食史对种群健康重要的成年性状的影响知之甚少。植物-昆虫草食动物相互作用的化学生态学研究大量集中在植物防御和毒性对昆虫幼虫阶段的直接影响上。由于昆虫幼虫往往会对植物造成最大的损害，因此这种关注是有道理的，但结果是只有有限的信息是间接的，即，在幼虫阶段之后，寄主植物毒性对成虫特征的影响对种群增长和扩散很重要。拟议的工作将通过将幼虫经历的植物防御生物化学变化与成虫昆虫适应结果联系起来来解决这一知识差距。使用标志性的帝王蝶作为焦点物种，PI旨在量化十种乳草物种（即，在实验室和自然环境中，帝王蝶寄主植物）影响幼虫的生长、成虫的繁殖力和迁移能力。为了实现这一目标，他们将使用一种综合方法，结合化学生态学，有机体能量学，生物力学的最先进方法，并利用公民科学驱动的合作，与位于沿着的几个实验室的年度君主的迁移路线。这项工作是相关的焦点物种，旨在恢复合适的栖息地，以打击君主人口下降的再植工作使用多种马利筋物种，而不考虑幼虫暴露于不同的马利筋防御化学影响君主的人口动态和迁移。与此同时，该项目将为科学和栖息地恢复工作提供信息，旨在抵消其他益虫种群数量的下降，因为大多数昆虫对幼虫饮食史对成虫特征的影响知之甚少。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The decline in North American populations of the Monarch butterfly has been linked to the loss of their milkweed host plant along US and Mexican migration routes. This has resulted in significant milkweed replanting efforts by national initiatives and local enthusiasts. While meritorious in its conception, these replanting efforts tend to use a variety of milkweed species that can vary dramatically in their level of toxicity to Monarch larvae. Moreover, it is unknown how exposure to such varying levels of toxicity as larvae may affect the ability of surviving adult Monarch butterflies to establish viable populations and migrate to Mexican overwintering sites. Using NSF funding and leveraging a large-scale collaborative network of Monarch scientists, the researchers will quantify such effects by examining milkweed-Monarch interactions throughout their life history, under both controlled laboratory- and natural settings. In addition to Monarchs, this project will generally inform habitat restoration efforts aimed at offsetting population declines in other beneficial insects, as consequences of larval dietary history for adult traits important to population health are poorly understood in most insects.Chemical ecology research on plant-insect herbivore interactions has abundantly focused on the proximate effects of plant defenses and toxicity on insect larval stages. Since insect larvae tend to cause most damage to plants, this focus makes sense, but as a result only limited information is available on indirect, i.e., beyond the larval stages, effects of host plant toxicity on adult insect traits important for population growth and dispersal. The proposed work will address this gap in knowledge by linking variation in plant defense biochemistry experienced by larvae to adult insect fitness outcomes. Using the iconic Monarch butterfly as a focal species, the PIs aim to quantify how variation in toxic traits among ten milkweed species (i.e., Monarch host plants) affect larval growth, adult fecundity and migratory ability, in laboratory and natural contexts. To achieve this aim, they will use an integrative approach that combines state-of-the-art methods in chemical ecology, organismal energetics, biomechanics, and leverage a citizen science driven collaboration with several laboratories located along the annual Monarch's migration routes. This work is pertinent to the focal species as replanting efforts aimed at restoring suitable habitat to combat Monarch population declines use multiple milkweed species without consideration for how larval exposure to varying milkweed defensive chemistry affects Monarch population dynamics and migration. In parallel, this project will generally inform science and habitat restoration efforts aimed at offsetting population declines in other beneficial insects, as consequences of larval dietary history for adult traits are poorly understood in most insects.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.