Structural Diversity with Varying Disorder Enables the Multicolored Display in the Longhorn Beetle Sulawesiella rafaelae

• Main Authors: Esteban Bermúdez-Ureña, Cédric Kilchoer, Nathan P. Lord, Ullrich Steiner, Bodo D. Wilts
• Format: Article
• Language: English
• Published: Elsevier 2020-07-01
• Series: iScience
• Subjects: Entomology; Materials Science; Biomaterials; Optical Materials
• Online Access: http://www.sciencedirect.com/science/article/pii/S2589004220305265

Summary: Light control through layered photonic nanostructures enables the strikingly colored displays of many beetles, birds, and butterflies. To achieve different reflected colors, natural organisms mainly rely on refractive index variations or scaling of a fixed structure design, as opposed to varying the type of structure. Here, we describe the presence of distinct coloration mechanisms in the longhorn beetle Sulawesiella rafaelae, which exhibits turquoise, yellow-green, and orange colors, each with a variable iridescence. By optical and electron microscopy, we show that the colors originate from multilayered architectures in hair-like scales with varying amounts of structural disorder. Structural characterizations and optical modeling show that the disorder strongly influences the optical properties of the scales, allowing an independent adjustment of the optical response. Our results shed light on the interplay of disorder in multilayered photonic structures and their biological significance, and could potentially inspire new ecological research and the development of novel optical components.