Asian Beetle Species Offer Insights on New Color, Material Strength

Scientists are looking at the exoskeleton of an Asian beetle species, using its unique properties to develop new technologies based on its color and mechanical strength.

An international team of scientists, including the University of Exeter's Professor Pete Vukusic, have examined the carapace of the flower beetle (Torynorrhina flammea), whose species constitute a subgroup of scarab beetles.

Details about the mechanical and optical properties of the exoskeleton of the T. flammea, and a multidisciplinary approach to understanding its design, appear in the article Microstructural design for mechanical-optical multifunctionality in the exoskeleton of the flower beetle Torynorrhina flammea. The study appears in the latest issue of the PNAS journal.

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Microstructures in the Flower Beetle Carapace

Researchers discovered that the flower beetle contains small micropillars in its carapace — or the upper layer of its exoskeleton. These microstructures give the small insect the strength and the flexibility to withstand damage.

The previously undiscovered microstructures consist of the micropillars embedded in the exoskeleton layer. Additionally, it also gives the flower beetle its unusual sheen — a bright metallic color.

Together with Prof. Vukusic, the study was led by Professor Ling Li from Virginia Polytechnic Institute and State University and Professor Mathias Kolle from the Massachusetts Institute of Technology. In a press release from Exeter, Prof. Vukusic noted that the breakthrough was only made possible by the collaborative efforts from their respective institutions and specialized laboratories in the fields of materials science, mechanics, and optics. The project traces its origins from 16 years ago, in a short project in the undergrad Physics labs in Exeter.

The original students who worked on the project first examined the form and structure of the beetle carapace, initially in an attempt to understand where the brilliant colors come from. In this study, they found the micropillars and how they contribute to the strength of the insect's "armor."

It led Prof. Vukusc to relay their findings to Prof. Li and Prof. Kolle, specialists in the fields of materials science and applied optics. Using more advanced equipment and modeling methods, the now-international research team further understood the role that the micropillars had in improving the mechanical strength of the flower beetle exoskeleton without losing its bright metallic sheen.

Taking Inspiration from Nature's Designs

Researchers say that the discovery made from the carapace of the flower beetle could help inspire a new generation of engineered materials inspired by nature. Aside from its implications in the future, an understanding of these microstructures could also help scientists gain insights from an evolutionary context — including finding evolutionary advantages that benefit these insects.

For materials science, by understanding the functions tied to the physiological features in the carapace, future researchers could help develop techniques to replicate these optical and mechanical characteristics.

"Such natural systems as these never fail to impress with the way in which they perform, be it optical, mechanical or in another area of function," Prof. Vukusic added. He explained that this unusual toughness, including its imperfections, offers insights into scientific and technological advancements.