Mechanisms of Fluid Feeding in Insects, from Nanoscale to Organism

食液昆虫是地球上最丰富的生物之一。它们的成功可以部分归功于它们的管状口器，通过自然选择来获得各种各样的液体，如血液和花蜜。这些喂食装置-长鼻-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。喙的基本结构由一个细长的管组成，表面有微小的谷和脊，形成由孔连接到中央食物通道的通道。该研究的重点是假设流体喂养可以解释一个单一的模型的基础上统一的原则毛细作用和润湿。为了验证这一主要假设，将使用两种主要昆虫类群（蝴蝶和苍蝇）来研究喙的结构和功能。该研究围绕三个目标组织：（1）解释作为获取液体的第一步的吻部的润湿性的作用，（2）阐明作为液体获取的第二步的液体摄取的机制，以及（3）解释液体的可用性，无论是在池中还是在膜中，如何决定摄取的方式。该项目为解释生物现象提供了一个新的框架，例如饮食选择和昆虫生活的多样化。它还提供了一个平台，用于将受自然启发的流体吸收和运输原理转移到新工程设备的开发中，例如灵活的微流体探针。该研究计划强调生物学家和物理科学家之间的跨学科互动，并从高中开始转化为学生的跨学科教育。通过提供研究机会和接待科学教师开发教学模块，向学生，包括代表性不足的群体的学生进行宣传，强调物理原理与自然方面的关系，如蝴蝶喂养和授粉。研究结果将被纳入两所大学的课程，并将通过纸质和电子出版物、专业和公共演讲以及学生开发的网站和博客进行传播。这项拟议的研究从研究人员的初步工作开始，这表明昆虫的液体进食可以在基于毛细管和润湿统一原理的单一模型下进行（亲水性和疏水性），这迄今为止已经被很好地探索。将使用工具和原则对（1）口器的微观结构（例如，扫描电子显微术，X射线断层摄影术），（2）微结构在获取和输送流体进入和通过口器中的作用和功能（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）材料润湿和流体流过不同导管（通过流体性质的全面表征（例如食品流变学、表面张力和接触角）增强的物理和数学建模），以及（4）口器的疏水-疏水性质（例如，共聚焦显微镜、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).