Causes turn dragonflies from gold to red

Chemical balance between the pigments in the dragonfly's abdomen determines their color. When oxidants are present, these cells are yellow and when there are reductants, they become red.

Finding out how to 'color' the dragonflies familiar to each of these rural children was discovered by Japanese scientists and published in the Proceedings of the National Academy of Sciences.

Many animals use brilliant colors to decorate their bodies, to camouflage or intimidate their enemies, to seduce opposite sexes in breeding seasons and other purposes. Poisonous insects use colorful colors to signal a warning that predators, birds and animals often make codes very beautiful during the couple's time.

The group of biologists led by Dr. Ryo Futahashi, National Institute of Advanced Science and Technology (AIST) in Tsukuba City (Japan) studied the extracted pigments from some Asian dragonflies. red, scientific name is Crocothemis servilia, Sympetrum darwinianum and Sympetrum frequens.

Scientists say these dragonflies use color to signal their sexual maturity. Adults are red and juveniles - yellow.

Mr. Futahashi and colleagues compared the chemical composition of pigment extracted from immature male dragonflies and found a mechanism to change their color.

They found that both types share a common pigment called xanthomatin in red and yellow cells. The color change of this substance depends on the chemical balance of the medium containing the dye molecules.

When there is a strong oxidizing agent, such as sodium nitrite, xanthomatin from red turns yellow, but when adding a reducing agent, for example ascorbic acid, they become the original golden brown color.

The authors examined their conclusions on live dragonflies by adding small amounts of ascorbic acid to the abdomen of both types of male dragonflies. As expected, after only a few hours these dragonflies were bright red - confirmed by chemical analysis.

Then the scientists tried to trick the dragonflies by bringing sodium nitrite into the male dragonflies' abdomen, turning them into 'adolescents' to see if the dragonflies have ' look chicken ' . Once again they were surprised because the oxidizing agent was only partially effective.

Non-golden male dragonflies resemble the old but only yellow spots. Also, that chemical is harmful to them. It causes the cells to be destroyed and they die as well.

Futahashi and colleagues said this color change mechanism is also characteristic of other insects, such as the wings of the solar butterfly (Heliconius) and the eye of fruit fly (Drosophila melanogaster).