In a new study published in February 2023 in the Journal of Luminescence, an international team of scientists led by Sébastien Mouchet of UNamur has revealed previously unknown fluorescent properties of the transparent wings of certain insects. This research demonstrates that valuable information can be obtained using state-of-the-art optical characterization techniques. Here’s how it works.
In the natural world, many animal species exhibit fluorescence, meaning they emit visible light under ultraviolet light. In general, the physical, chemical, or biological properties underlying fluorescence in these species are poorly understood. For example, the fluorescence of the transparent wings of the more than 3,000 species of cicadas had never been reported in the scientific literature until this year.
In a new study published in February 2023 in the Journal of Luminescence, an international research team led by Sébastien Mouchet, a researcher in the Department of Physics and a member of the NISM (Namur Institute of Structured Matter) and ILEE (Institute of Life, Earth and Environment) at UNamur, has revealed the previously unknown fluorescent properties of the transparent wings of certain insects, including cicadas found in southern France and the gas-colored sphinx moth, a lepidopteran found in Belgium, among other places.
This study suggests that fluorescence light emission is more common in the transparent wings of insects than previously thought. Everything points to the presence of resilin within the wings as the source of this fluorescence. This protein is known to contribute to the flexibility of the wings.
Contrary to previous beliefs, the fluorescence observed in these insects may be an unintended consequence of resilin’s presence in the wings for mechanical purposes and may not play a specific role in the insect’s visual communication, whether for courtship or territorial defense.
The optical characterization we conducted also allowed us to gain a better understanding of the wing’s structure. The techniques we used are rarely employed in studies of naturally fluorescent organisms. Our research has thus demonstrated that valuable insights can be obtained using these techniques.
The fundamental study of fluorescence in living organisms is not only crucial from a zoological perspective. The discovery of green fluorescent protein (GFP) in the tissues of a species of jellyfish revolutionized the fields of genetics and fluorescence microscopy. This discovery was honored with the Nobel Prize in Chemistry in 2008.
At UNamur, these studies were conducted using equipment from the LOS (Lasers, Optics, and Spectroscopies) technology platform.
The platform offers unique expertise in characterizing the optical and electronic properties of matter using linear and nonlinear optical measurements, performed in particular with lasers within the context of basic or applied research. The platform enables the analysis of structured systems at the nanoscale in one, two, or three dimensions, as well as molecular films at interfaces or trace gases. In addition to its experimental capabilities, the platform develops analytical and numerical models to interpret the measured spectroscopic responses.
This feature is commonly used in our daily lives. Here are a few examples:
Fluorescence is also used in so-called “black light,” which is light emitted by a source composed primarily of near-ultraviolet rays. This light highlights white and fluorescent objects to create a special atmosphere, verify that a banknote is not counterfeit, or detect certain substances invisible to the naked eye.
In leak detection, fluorescence is widely used by mixing fluorescent tracers with water. This makes it possible to detect any type of water infiltration or flow. A prime example is the UNamur spin-off TRAQUA, an expert in hydrological and hydrogeological monitoring, which developed the STREAM® fluorimeter/turbidimeter.
Sébastien Mouchet and Oliver Deparis are the authors of a book titled *Natural Photonics and Bioinspiration*. Published in November 2021, it is a book on the topics of physical optics and environmental biology. Building on the research of Prof. Jean-Pol Vigneron, this book—described by the publisher as groundbreaking—opens the door to bio-inspired applications in the fields of optics, energy, and the environment.