Collaborative Research: The interplay between fluctuating selection on symbionts and life cycle evolution in sap-sucking insects

以寄主植物的汁液为食的昆虫，包括许多农作物和森林害虫，体内有有益的细菌，这些细菌为昆虫提供了它们饮食中缺乏的必需营养素。这项研究量化了这些细菌的特性是如何受到昆虫饮食进化变化的影响的；它进一步探讨了细菌在昆虫如何利用新的寄主植物和昆虫的生命周期中所起的作用。这一知识很重要，因为它强调了细菌在昆虫生态学和进化的主要方面是隐藏的参与者。这个项目提供的资料也可能有助于控制几种森林害虫。该项目将为研究生、本科生和高中生提供培训，包括来自科学领域代表性不足群体的个人，并将促进公共活动，以提高科学素养和对研究的欣赏。本项目研究以针叶树为食的针叶树科昆虫及其双重共生体。它验证了这样一个假设，即昆虫对营养供应的波动需求导致了共生替换，这反过来又促成了新的寄主植物获取和生命周期的复杂性。具体目标包括：(1)建立双共生体之间不寻常角色分配的全家族模式；(2)量化共生体和昆虫宿主对养分供给的贡献，作为调节养分有效性的措施；(3)量化昆虫不同摄食方式下共生体基因组的进化速率。这些目标将通过对共生体基因组和支持共生体功能的昆虫表达基因的DNA和RNA测序来实现。

Insects that feed on the sap of their host plants, including many crop and forest pests, have within them beneficial bacteria that provide the insects with essential nutrients that are missing from their diet. This research quantifies how the properties of those bacteria have been affected by evolutionary changes in insect diets; it further explores the role that the bacteria have played in how the insects use new host plants and in the insect's life cycle. This knowledge is important because it highlights bacteria as hidden players in major aspects of insect ecology and evolution. Information from this project may also assist in the control of several forest pest insects. This project will provide training for graduate students, undergraduates, and high-school students, including individuals from groups that are underrepresented in the sciences, and will promote public events to enhance scientific literacy and appreciation for research.This project studies Adelgidae insects that feed on conifer trees, and their dual symbionts. It tests the hypothesis that fluctuating demands for nutrient provisioning in insects has led to symbiont replacements, which in turn have precipitated new host-plant acquisitions and life-cycle complexity. Specific objectives include (1) establishing a family-wide pattern of the unusual role allocations between dual symbionts; (2) quantifying the contributions of symbionts and insect hosts to nutrient provisioning as a measure of adjustment to nutrient availability; (3) quantifying rates of evolution in symbiont genomes under different insect feeding modes. These objectives will be accomplished through DNA and RNA sequencing of symbiont genomes and expressed insect genes that support symbiont functions.