Mechanisms of Fluid Feeding in Insects, from Nanoscale to Organism

流食昆虫是地球上最丰富的生物之一。它们的成功在一定程度上可以归功于它们的管状口器，通过自然选择获得各种液体，如血液和花蜜。这些喂食装置--吸管--必须吸收液体，同时保持没有可能阻碍液体吸收的粘性残留物和碎片；换句话说，它们必须能够自我清洁。喙的基本结构由细长的管子组成，管子的表面有微小的山谷和脊状结构，形成由毛孔连接到中央食物管道的管道。这项研究的重点是一种假设，即根据毛细作用和润湿的统一原理，可以用单一的模型来解释流体的供给。为了验证这一基本假设，将使用两个主要的昆虫群体--蝴蝶和苍蝇--来研究鼻子的结构和功能。这项研究围绕三个目标进行：(1)解释鼻子的润湿性作为获取流体的第一步的作用，(2)阐明作为流体获取的第二步的流体摄取的机制，以及(3)解释流体的可用性如何决定摄取方式，无论是在水池中还是在薄膜中。该项目为解释生物现象提供了一个新的框架，如饮食选择和昆虫生命的多样化。它还提供了一个平台，用于将自然启发的流体吸收和传输原理转化为新工程设备的开发，如柔性微流控探头。该研究计划强调生物学家和物理学家之间的跨学科互动，并将其转化为从高中开始的学生跨学科教育。向学生，包括代表性不足群体的学生进行宣传，提供研究机会，并接待科学教师开发教学单元，强调物理原理与自然界各方面的关系，如蝴蝶喂食和授粉。研究成果将被纳入两所大学的课程，并将通过纸质和电子出版物、专业和公开演讲以及学生开发的网站和博客进行传播。拟议的研究始于研究人员的初步工作，该工作表明，昆虫的液体觅食可以在基于毛细和润湿(亲水性和疏水性)统一原则的单一模型下捕获，而到目前为止，对这一原理的探索还很少。将使用工具和原理对(1)口器的微结构(例如扫描电子显微镜、X射线断层扫描)、(2)微结构在获取流体进入口器和通过口器传输流体方面的角色和功能(例如X射线相衬成像、荧光和暗场光学显微镜以及数学图像分析)、(3)材料的润湿和流体通过不同管道的流动(通过充分表征流体特性，例如食品流变学、表面张力和接触角)进行定量和比较分析。以及(4)口器的亲水性-疏水性(例如，共焦显微镜、荧光成像、原子力显微镜)。

Fluid-feeding insects are among the most abundant organisms on Earth. Their success can be attributed in part to their tubular mouthparts, engineered by natural selection to acquire a remarkable variety of fluids, such as blood and nectar. These feeding devices - proboscises - must take up fluids while remaining free of sticky residues and debris that might impede fluid uptake; in other words, they must be capable of self-cleaning. The fundamental organization of the proboscis consists of a slender tube with a surface of minute valleys and ridges that form canals connected by pores to a central food canal. The research focuses on the hypothesis that fluid feeding can be explained by a single model based on unifying principles of capillarity and wetting. To examine this primary hypothesis, two major insect groups, butterflies and flies, will be used to study the structure and function of the proboscis. The study is organized around three objectives: (1) to explain the role of wettability of the proboscis as the first step in acquiring fluid, (2) to elucidate the mechanisms of fluid uptake as the second step in fluid acquisition, and (3) to explain how the availability of fluid, whether in pools or films, determines the means of uptake. The project offers a new framework for explaining biological phenomena, such as dietary choices and the diversification of insect life. It also provides a platform for transferring Nature-inspired principles of fluid uptake and transport to the development of new engineering devices, such as flexible microfluidic probes. The research program emphasizes cross-disciplinary interaction between biologists and physical scientists and translation into interdisciplinary education of students, from high school onward. Outreach to students, including those in under-represented groups, by providing research opportunities and by hosting science teachers to develop teaching modules emphasizing the relation of physical principles to aspects of Nature, such as butterfly feeding and pollination. Research results will be incorporated into courses at two universities and will be disseminated through paper and electronic publications, professional and public presentations, and student-developed web sites and blogs.The proposed study launches from preliminary work by the investigators, which indicates that fluid feeding by insects can be captured under a single model based on unifying principles of capillarity and wetting (hydrophilicity and hydrophobicity), which heretofore have been poorly explored. Tools and principles will be used to provide a quantitative, comparative analysis of the (1) micro-architecture of the mouthparts (e.g., scanning electron microscopy, X-ray tomography), (2) role and function of micro-architecture in acquiring and transporting fluids into and through the mouthparts (e.g., X-ray phase-contrast imaging, fluorescent and dark-field optical microscopy, and mathematical image analysis), (3) materials wetting and fluid flow through different conduits (physical and mathematical modeling augmented by full characterization of fluid properties such as food rheology, surface tension, and contact angles), and (4) hydrophilic-hydrophobic properties of the mouthparts (e.g., confocal microscopy, fluorescent imaging, Atomic force microscopy).