Collaborative Research: RUI: Insect herbivore feeding guilds and compartmentalized plant defense

植物是几乎所有食物链的基本能源，负责养活世界。 然而，在过去的20年里，昆虫对植物的巨大压力导致了一种显着多样性的策略的进化，以防止被消耗。植物用毒素、刺和粘稠的树液进行防御。尽管植物性状可以减少植食性的示范，在大多数野生植物系统中，科学家缺乏对植物防御反应机制的理解。植物是否会产生针对食根动物而不是食叶动物的特定毒素，而不会毒害传粉者等有益的访客？ 破译植物防御机制不仅可以推进生态学和进化的科学知识，而且可能具有重要的社会效益。由于野生植物一直在与害虫进行长期的进化斗争，研究防御机制可能会提高作物害虫管理。这个项目的重点是乳草，这是唯一的主机为下降的帝王蝶。 将获得帝王蝶和马利筋之间相互作用的基本知识，这可能有助于维持帝王蝶受到威胁的迁徙。 该项目融合了基因组操作，毒理学和化学的最新进展，将培养科学家融合自然历史和重要的生态问题。 研究人员将通过学校、演讲和博客扩大与公众的交流。关于植物防御如何针对不同的攻击者，是否存在与多种军备竞赛相关的权衡，以及组织特异性表型可塑性是否是管理与多种害虫相互作用的一种手段，人们知之甚少。这项工作使用乳草作为一个模型的自然系统，具有良好的特点的防御化学测试的特异性和相互依赖性的相互作用与不同的昆虫攻击者，包括食叶帝王蝶，食根甲虫，种子喂养错误。从植物的角度来看，权衡多种防御和它们的非目标影响授粉熊蜂作为成本与组成或诱导防御之间进行评估。从食草动物的角度来看，植物毒素表达的测定将与对昆虫靶位点酶功能、行为和整个生物体性能的影响相结合。除了行业协会特定的植物防御和权衡的假设，在植物防御多样性的经典解释也将被测试：非排他性的假设，即（i）天然存在的毒素混合物在植物部分的差异表达和（ii）混合物比相同剂量的单一化合物更有效。这种关于专业化和相互作用的观点解决了进攻-防御特征的动态匹配，这些特征可能通过从根到果实的不同军备竞赛在植物和昆虫中产生多样性。饲养试验将用于解决单一的Cardenolides和天然混合物如何影响生理功能，昆虫行为，螯合和健身。通过从不同昆虫中提取Na/K-ATPase（强心内酯的靶点），毒素的具体作用也将在体外进行评估。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。

Plants are the basic energy source in nearly all food chains and are responsible for feeding the world. Yet over the eons, tremendous insect pressure on plants has led to the evolution of a remarkable diversity of tactics to defend against being consumed. Plants defend with toxins, spines, and sticky sap. Despite demonstrations of how plant traits can reduce herbivory, in most wild plant systems scientists lack an understanding of the mechanisms of plant defensive responses. Do plants make specific toxins targeted at root feeders versus leaf feeders, all the while not poisoning beneficial visitors such as pollinators? Deciphering the mechanisms of plant defense not only advances scientific knowledge of ecology and evolution but may have important societal benefits. Because wild plants have been engaged in a long-term evolutionary battle with insect pests, studying the mechanisms of defense may enhance crop pest management. This project focuses on milkweeds, which are the only host for the declining monarch butterfly. Basic knowledge of the interaction between monarchs and milkweed will be gained, which could help sustain the monarch's threatened migration. This project blends the latest advances in genomic manipulation, toxicology and chemistry in a way that will train scientists to meld natural history and important ecological problems. The investigators will expand their communication to the public through schools, presentations, and a blog.Little is known about how plant defenses are aimed at different attackers, whether there are trade-offs associated with multiple arms races, and whether tissue-specific phenotypic plasticity is a means to manage interactions with several pests. This work uses milkweeds as a model natural system with well-characterized defense chemistry to test the specificity and interdependence of interactions with diverse insect attackers that include leaf-feeding monarch butterflies, root-feeding beetles, and seed-feeding bugs. From the plant's perspective, trade-offs will be evaluated between multiple defenses and their non-target impacts on pollinating bumblebees as costs associated with constitutive or induced defenses. From the herbivores' perspective, assays of plant toxin expression will be coupled to impacts on insect target site enzymatic function, behavior, and whole-organism performance. Beyond guild-specific plant defense and trade-off hypotheses, classic explanations for diversity in plant defense will also be tested: the non-exclusive hypotheses that (i) naturally occurring toxin mixtures are differentially expressed in plant parts and (ii) mixtures are more effective than equal doses of single compounds. This view on specialization and interaction addresses the dynamic match in offense-defense traits that may generate diversity within plants and insects through distinct arms races occurring from roots to fruits. Feeding trials will be used to address how single cardenolides and natural mixtures impact physiological function, insect behavior, sequestration, and fitness. By extracting the Na/K-ATPase (the target of cardenolides) from the different insects, the specific action of toxins will also be assessed in vitro.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.