WASHINGTON, April 25Costa Rica was once regarded as the poorest of all the colonies of the Spanish Empire, sadly deficient in the silver and gold so coveted by conquistadors. As it turns out, all of the glittering gold and silver those explorers could have ever wanted was there all along, in the country's tropical rainforestsbut in the form of two gloriously lustrous species of beetle.
Today, the brilliant gold- (Chrysina aurigans) and silver-colored (Chrysina limbata) beetles have given optics researchers new insights into the way biology can recreate the appearance of some of nature's most precious metals, which in turn may allow researchers to produce new materials based on the natural properties found in the beetles' coloring.
A team of researchers at the University of Costa Rica has found that the beetles' metallic appearance is created by the unique structural arrangements of many dozens of layers of exo-skeletal chitin in the elytron, a hardened forewing that protects the delicate hindwings that are folded underneath. A paper about the discovery appears in the first issue of the Optical Society's (OSA) newest open access journal, Optical Materials Express, which launched this month.
The beetles were captured in the University of Costa Rica's Alberto Brenes Mesn Biological Reserve, a tropical rainforest environment. "The metallic appearance of these beetles may allow them to be unnoticed, something that helps them against potential predators," says physicist and study leader William E. Vargas. The surface of their elytra "reflects light in a way that they look as bright spots seen from any direction," he explains. "In a tropical rainforest, there are many drops of water suspended from the leaves of trees at ground level, along with wet leaves, and these drops and wet leaves redirect light by refraction and reflection respectively, in different directions. Thus, metallic beetles manage to blend with the en
|Contact: Angela Stark|
Optical Society of America