Semester of Graduation

Fall

Degree

Master of Science (MS)

Department

Entomology

Document Type

Thesis

Abstract

The jewel beetles, (Coleoptera: Buprestidae Leach, 1815), is the eighth most speciose coleopteran family, with the majority of its members possessing diverse bright, saturated structural coloration of multilayer origin. This study focuses on the genus Chrysochroa Dejean, 1833, which includes some of the most brilliantly and charismatically colored buprestid species. While members of Chrysochroa are prised by entomologists amateurs and professional and are well-represented in museum collections, the evolution and ecology of their structural color remain underexplored. Twenty-eight select taxa including exemplars from all 13 subgenera of Chrysochroa were investigated to provide an overview of the objective optical properties and underlying mechanisms of their diverse structural color. The optical properties structural colors were quantified using spectrophotometry. This study resulted in the identification and categorization of three major morphological adaptations through which members of Chrysochroa modify color: 1) cuticle surface sculpture, 2) outer-exocuticle chitin-melanin multilayer organization, and 3) refractive index modification within each layer. Each of these variables were investigated and characterized using Transmission (TEM) and Scanning (SEM) Electron Microscopy. The relationships between multilayer organization and measured optical properties were tested through transfer-matrix modeling. This study revealed six novel multilayer organizations, each producing unique, previously unobserved reflectance spectra, structural coloration reflecting maximally in the infrared wavelength range, and surface sculpture assisted structural blackness. The surface sculpture morphology and multilayer organization in Chrysochroa members were characterized and categorized based on morphology to assist future endeavors in buprestid structural color research.

Date

11-2-2022

Committee Chair

Lord, Nathan

DOI

10.31390/gradschool_theses.5682

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