A new study has revealed that the oriental hornet has built-in 'solar cells' that generate electricity from sunlight - a first in the animal kingdom.

Study leader Marian Plotkin of Tel-Aviv University, said that scientists already knew that the hornet species, for unknown reasons, produced electricity inside its exoskeleton.

It was previously found that he insect is active when the sun is most intense - unusual for hornets.

In the new study, Plotkin and colleagues went a step further by examining the structure of the hornet's exoskeleton to find out how the electricity is produced.

Their research has revealed that pigments in the hornet's yellow tissues trap light, while its brown tissues generate electricity. Exactly how the hornets use this electricity is still not entirely understood, noted Plotkin.

While solar cells using human-made substances are usually 10 to 11% efficient at generating electricity, the hornet's cells are only 0.335% efficient.

"We've seen solar harvesting in plants and bacteria, but never before in animals," National Geographic News quoted Plotkin as saying.

The team found that many of the hornet's brown tissues contain melanin, the pigment that protects human skin cells by absorbing damaging ultraviolet light and transforming it into heat.

A structural analysis of the brown tissues also uncovered grooves that capture light by channelling rays into the tissues and breaking them apart into smaller rays.

The hornet's yellow tissues contained the obscure pigment xanthopterin, which gives butterfly wings and mammal urine their color.

When the team isolated xanthopterin in a liquid solution, and then placed the solution inside a solid solar cell electrode, a type of conductor. When the scientists shed light on the electrode, the pigment in the solution generated electricity.