Parker and his colleagues discovered P. argus in a collection of dead and damaged weevils and beetles stored in a museum collection at Oxford. The insects serve educational purposes but are of no use to the museum because they lack sufficient data.
After noticing the weevil's color, the researchers cut into it and examined it under an electron microscope, which revealed the opal-like inner structure of the scales.
The team is now in the process of acquiring live specimens from Southeast Asia so that they can study how the cells build the structures, looking for little tricks they perform with molecular motors, rulers, and templates, said Parker.
"Are they made within the cells and extruded out or does [the structure] form during the extrusion process?" he said. "We should be able to answer that in the next project."
The researchers will also study the weevil's genetics, to see if they can detect the genes that control for patterns and the size of the tiny opal-like spheres.
The Opal Advantage
Why P. argus evolved the opal-like structures remains an open question, said Parker, but it may be related to helping the weevils recognize each other, as each has a unique pattern.
He has identified several other species of beetles with the opal structure, ranging from bright red to violet, a sign that the color may be important for species recognition.
Ratcliffe said many insects, including the beetles he studies, rely on chemical signals and touch for mate recognition.
"I think it acts as a camouflage to protect it from animals," he said. Many scarab beetles are metallic in color, which allows them to blend into wet forests and avoid predation by birds. Ratcliffe thinks the weevil does this as well.
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