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。它们的成功部分归功于它们的管状口器，这些管状口器是通过自然选择设计的，可以获取各种各样的液体，例如血液和花蜜。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。长鼻的基本组织由一根细长的管子组成，管子的表面有微小的谷和脊，形成通过孔连接到中央食物道的通道。该研究的重点是假设液体喂养可以通过基于毛细管作用和润湿统一原理的单一模型来解释。为了检验这一初步假设，将使用蝴蝶和苍蝇这两个主要昆虫类群来研究长鼻的结构和功能。该研究围绕三个目标进行：(1) 解释长鼻润湿性的作用，作为获取液体的第一步；(2) 阐明液体摄取的机制，作为液体获取的第二步；(3) 解释液体的可用性，无论是在池中还是在膜中，如何决定摄取方式。该项目提供了一个新的框架来解释生物现象，例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，例如柔性微流体探针。该研究项目强调生物学家和物理科学家之间的跨学科互动，并将其转化为高中以上学生的跨学科教育。通过提供研究机会和接待科学教师开发强调物理原理与自然各方面（例如蝴蝶喂养和授粉）之间关系的教学模块，向学生（包括代表性不足群体的学生）进行宣传。研究结果将纳入两所大学的课程中，并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。拟议的研究从研究人员的初步工作开始，这表明昆虫的液体摄食可以在基于毛细管作用和润湿（亲水性和疏水性）统一原理的单一模型下捕获，而迄今为止对此的探索很少。将使用工具和原理对以下方面进行定量、比较分析：(1) 口器的微结构（例如，扫描电子显微镜、X 射线断层扫描），(2) 微结构在采集和输送流体进入和通过口器的过程中的作用和功能（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) 材料润湿和通过不同管道的流体流动（物理）。 (4) 口器的亲水-疏水特性（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).