Secret to firefly light? Natural Viagra

June 28, 2001 Posted: 1:33 PM EDT (1733 GMT)

This Photinus firefly must look for love quickly during its brief adulthood

By Richard Stenger
CNN

(CNN) -- Scientists have identified the elusive chemical that fireflies use to turn their flashing bellies on and off, the same one that helps regulate heartbeats, aids memory and triggers erections in humans.

The chemistry that makes fireflies glow has been known for years according to insect researchers. But how hundreds of species of the bug could blink their lights in precise, distinct patterns remained a mystery until this week when a team of researchers reported that the key was nitric oxide.

Nitric oxide carries messages between cells and plays a major role in treating impotence. The popular drug Viagra facilitates penile erection by regulating the simple molecule.

As in humans, nitric oxide stokes passion in fireflies, which have evolved intricate mating rituals based on flash communications.

"Fireflies are very romantic beasts because their whole adult life is spent courting," said Tufts University's Sara Lewis, the co-author of a report in the Friday edition of the journal Science.

While intense, the romance is fleeting. After spending two years as juvenile larvae, eating insects, worms and slugs on the ground, fireflies, which are actually beetles, not flies, enjoy adulthood for all of two weeks.

Two fireflies mate

Finding a mate quickly becomes a considerable challenge. Males fly around blinking a particular sequence, hoping to attract the blinking reply of an interested female. And each of the more than 2,000 species has a distinguishing flash pattern.

The scientific team, which included an insect neurobiologist, evolutionary ecologist and cardiologist, found that live fireflies glowed almost constantly in the presence of nitric oxide. When they removed the gas, the flashing stopped.

Under the microscope, the researchers discovered how the bioluminescent process worked. When certain cells produce nitric oxide, the chemical shuts down the operation of mitochondria, mini-organs inside cells that use oxygen to produce cellular energy.

The work stoppage frees up floods of oxygen, which then fuels light production. When the burst of nitric oxide subsides, the mitochondria power up and consume the oxygen again, which turns the lantern off. The entire process happens in a flash, so to speak.

"Amazingly enough, it's a temporary cut in the power supply that probably triggers the firefly flash," said Barry Trimmer of Tufts University, lead author of the Science study.