The body shell of the Oriental hornet converts sunlight into electricity. Go figure.
A team of researchers led by Marian Plotkin of Tel-Aviv University made this discovery and then decided to mimic it. They published their findings in the journal, Naturwissenschaften. You can download the paper here.
Observations of the insect by previous researchers revealed that unlike other wasps that are more active in the early morning, the Oriental hornet is most active in the middle of the day. What's more, the hornets seems to correlate the business of digging its underground nest with the intensity of the sun. The more sunlight, the more active the hornet is with nest digging.
In 2008, a group of scientists looked at different weather conditions, such as temperature, humidity and solar radiation, to see if any of those factors influenced the hornets' digging. The team found that the only significant factor was UVB radiation.
On top of that, Plotkin and other researchers have made some interesting discoveries about the body of the Oriental hornet. The brown and yellow parts of its body have the ability to absorb solar radiation, and a pigment in the yellow area is known to play a role in photosynthesis.
All of these clues lead Plotkin and her team to hypothesize that the hornet's body shell, or exoskeleton, was able to harvest solar energy.
So they used a special microscope that's able to look at nano-sized details, and analyzed the hard layers of the hornet's exoskeleton.
They found that the brown shell is made of an array of grooves that split sunlight into diverging beams. The yellow parts has small oval-shaped protrusions, each with one or two "pinhole" depressions. The yellow sections also contain the pigment xanthopterin tightly packed in granules. Xanthopterin has the ability to change light into electrical energy. So basically the shell is trapping sunlight and the xanthopterin is converting it to energy.
The team also modeled the structure of the hornet's body by building a solar cell that used xanthopterin as the light-harvesting molecule. But because they were unable to precisely model the complex nanostructures found in the shell, the solar cell had a low conversion rate. For their next work, they'll be looking at how to replicate the intricate grooves and pinhole depressions. It could happen that one day, we have solar cells inspired by the Oriental hornet.
Photo: Wikimedia Common [via BBC Earth News and Gizmag]