Dimensions U.S.-China: The role of symbiotic microbes in the invasion process of emerald ash borer and red turpentine beetle

随着全球旅行和商业的增加，入侵物种是一个日益严重的问题。这个项目调查了两种入侵昆虫，它们侵扰、捕食和杀死活着的树木。自20年前从东亚传入美国以来，这种翡翠白蜡虫已经杀死了数亿棵北美白蜡树。预计它将对苗圃和林业造成超过100亿美元的损失，并极大地改变天然林的构成。相反，原产于北美的红松节油甲自从20世纪70年代从美国引进以来，已经成为中国松林的主要害虫。不幸的是，人们对这些入侵甲虫如何适应新环境成为如此具有破坏性的入侵病原体知之甚少。与甲虫相关的微生物，要么生活在它们的肠道里，要么从一棵树带到另一棵树的甲虫表面，可能起到了重要作用。与其他甲虫物种相关的真菌和细菌可以降解木材，导致树木病害，或者产生挥发性化学物质，将更多的甲虫吸引到被感染的树木上。相比之下，其他微生物可能是昆虫病原体，它们产生的毒素可能有助于控制甲虫的数量。这项研究将利用美国和中国对这些入侵甲虫相关的微生物进行培养和基因组测序，以了解它们的生物多样性，以及它们如何发挥作用，帮助它们的昆虫宿主成为入侵物种。这项研究还有可能确定可用于这些森林病原体的生物防治的微生物。该项目将通过城市农贸市场的展品、社区研讨会和公共网站与公众分享成果。它还将培训STEM中代表性不足的群体的本科生和研究生，并通过教育交流和研讨会建立国际合作。尽管它们在多营养相互作用中很重要，但昆虫的微生物共生及其在塑造生物多样性和维持森林生态系统稳定方面所起的隐藏作用往往被忽视。这项建议将调查与入侵钻木甲虫相关的微生物的系统发育、功能和遗传多样性，以了解它们在促进昆虫宿主入侵方面的作用。目标1将使用基于微生物培养和代码子序列的系统发育多样性的群落分析以及功能分析来揭示系统发育多样性和功能多样性之间的关系。该项目将研究微生物群落的特定代谢功能，这些微生物群落通过降解木材中的木质纤维素、植物防御化合物的解毒和产生提高甲虫生存的代谢物(例如维生素和激素)或抑制入侵过程(例如昆虫寄生或昆虫毒素的合成)来促进入侵过程。目标2将使用计算方法比较每种甲虫原生和入侵范围内微生物群落中分类群和/或基因功能的网络，以询问微生物之间新的共生相互作用的进化是否会导致有助于入侵的新陈代谢创新。AIM 3将利用与入侵范围相关的真菌物种的基因组测序来研究微生物进化遗传过程(例如水平基因转移和基因组重排)如何改变其昆虫宿主的表型并驱动入侵共生的进化。该项目将阐明甲虫的微生物共生体如何帮助扩展其昆虫宿主的功能表型。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With increased global travel and commerce, invasive species are a growing problem. This project investigates two invasive insects that infest, feed upon, and kill living trees. The emerald ash borer has killed hundreds of millions of North American ash trees since its introduction to the U.S. from East Asia two decades ago. It is expected to cause more than $10 billion in damage to the nursery and forestry industries as well as drastically change the composition of natural forests. Conversely, the red-turpentine beetle, native to North America, has become a major pest of pine forests in China since its introduction from the U.S. in the 1970s. Unfortunately, very little is understood about how these invasive beetles adapt to their new environments to become such destructive invasive pathogens. Microbes associated with beetles, either found living inside their guts or carried on the surface of the beetle from tree to tree, likely play an important role. Fungi and bacteria associated with other beetle species can degrade wood, cause tree disease, or produce volatile chemicals that attract even more beetles to an infested tree. In contrast, other microbes may be insect pathogens that produce toxins that could help control beetle populations. This research will employ both culturing and genome sequencing of microbes associated with these invasive beetles in both the U.S. and China in order to understand their biodiversity and how they may function to aid their insect hosts in becoming invasive species. The research also has potential to identify microbes that could be deployed for biological control of these forest pathogens. The project will share results with the public through exhibits at urban farmer’s markets, community workshops, and a public website. It will also train undergraduate and graduate students from underrepresented groups in STEM and build international collaboration through educational exchange and workshops.Despite their importance in multi-trophic interactions, microbial symbionts of insects and the hidden roles they play in shaping biodiversity and maintaining the stability of forest ecosystems are often overlooked. This proposal will investigate the phylogenetic, functional, and genetic diversity of microbes associated with invasive wood-boring beetles to understand their role in facilitating invasion of their insect hosts. Aim 1 will use community analyses of phylogenetic diversity based on microbial culturing and metabarcode sequencing along with functional assays to uncover relationships between phylogenetic and functional diversity. The project will investigate specific metabolic functions of microbial communities that either contribute to the invasion process through degradation of lignocellulose in wood, detoxification of plant defense compounds, and production of metabolites that enhance beetle survival (e.g. vitamins and hormones) or that inhibit the invasion process (e.g. insect parasitism or synthesis of insect toxins). Aim 2 will use computational approaches to compare networks of taxa and/or gene functions in microbial communities from native and invasive ranges of each beetle to ask whether the evolution of novel symbiotic interactions between microbes leads to metabolic innovations that assist invasion. Aim 3 will use genome sequencing of fungal species associated with the invasive range to ask how microbial evolutionary genetic processes (e.g. horizontal gene transfer and genomic rearrangements) may alter the phenotypes of their insect hosts and drive the evolution of invasive symbioses. The project will elucidate how microbial symbionts of beetles help extend the functional phenotypes of their insect hosts.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.