Data from: Mouthpart conduit sizes of fluid-feeding insects determine the ability to feed from pores

Fluid-feeding insects, such as butterflies, moths and flies (20% of all animal species), are faced with the common selection pressure of having to remove and feed on trace amounts of fluids from porous surfaces. Insects able to acquire fluids that are confined to pores during drought conditions would have an adaptive advantage and increased fitness over other individuals. Here, we performed feeding trials using solutions with magnetic nanoparticles to show that butterflies and flies have mouthparts adapted to pull liquids from porous surfaces using capillary action as the governing principle. In addition, the ability to feed on the liquids collected from pores depends on a relationship between the diameter of the mouthpart conduits and substrate pore size diameter; insects with mouthpart conduit diameters larger than the pores cannot successfully feed, thus there is a limiting substrate pore size from which each species can acquire liquids for fluid uptake. Given that natural selection independently favoured mouthpart architectures that support these methods of fluid uptake (Diptera and Lepidoptera share a common ancestor 280 Ma that had chewing mouthparts), we suggest that the convergence of this mechanism advocates this as an optimal strategy for pulling trace amounts of fluids from porous surfaces.

流体取食昆虫（涵盖蝴蝶、蛾类与双翅目昆虫，占所有动物物种的20%）普遍面临一项选择压力：需从多孔表面获取并取食微量流体。在干旱环境中能够获取孔隙内封闭流体的昆虫，相较于其他个体将拥有适应性优势与更高的进化适合度。本研究通过使用搭载磁性纳米颗粒的溶液开展取食实验，证实蝴蝶与双翅目昆虫的口器以毛细作用为核心原理，具备从多孔表面抽取液体的能力。此外，从孔隙中获取液体并完成取食的能力，取决于口器导管直径与基底孔隙直径之间的匹配关系；若昆虫口器导管直径大于孔隙，则无法成功取食，因此每个物种都存在可供其获取流体的基底孔隙尺寸上限。鉴于自然选择独立青睐支持这类流体取食方式的口器结构（双翅目与鳞翅目在2.8亿年前拥有具有咀嚼式口器的共同祖先），我们认为，该取食机制的趋同演化证明，这是从多孔表面抽取微量流体的最优策略。