Two fruit flies mating on a leaf. Two fruit flies mating on a leaf. See those fruit flies over there? They're a source of great interest for researchers. (Photo: Nikjuzaili / Shutterstock)

Fruit flies have orgasms – and, apparently, they’re amazing

In bizarre research project, scientists also discover why some fruit flies avoid getting drunk.

When you study biology in college, the last thing you think you're going to research is insects. Well, a Ph.D. student at Bar Ilan University in Israel went a step further. She studied the sex lives of fruit flies.

Shir Zer-Krispil and her colleagues at the university near Tel Aviv – along with researchers at the Maryland-based Howard Hughes Medical Institute – just published their research in the peer-reviewed journal of Current Biology.

In particular, they found two things: One, fruit flies have mind-bending orgasms. And two, the fruit flies in the experiment preferred not to get drunk.

Researching that on humans would be difficult enough, so how did they discover these behavioral patterns in fruit flies? They used a technique called optogentics, which involves the use of light to control cells in neurons that have been genetically modified to express light-sensitive ion channels. Put more simply, they knew which neuron controlled the release of sperm. By exposing the fruit fly to a red light, they were able to turn on that neuron. (This gives a whole new meaning to the term "Red Light District.")

"We wanted to know which part of the mating process entails the rewarding value for flies," said Galit Shohat-Ophir, a nanotechnology professor at Bar Ilan University who assisted on the project. "The actions that males perform during courtship? A female's pheromones? The last step of mating which is sperm and seminal fluid release?" They discovered that the flies were deriving pleasure from the last step itself, even without a sexual encounter.

See that fruit fly over there? It's a source of great interest for researchers. Fruit flies, of all creatures, have very active sex lives. (Photo: Thithawat.S / Shutterstock)

The researchers then conducted another test. From previous research, Shohat-Ophir knew that sexually deprived male flies prefer an alcoholic drink over a non-alcoholic one, presumably as an alternative reward. But the flies in this experiment – which simply had their neurons stimulated, but did not have sex – actually shunned alcohol.

This discovery could help doctors further understand a person's risk for developing an addiction. "The principles by which the brain processes reward are extremely conserved in all animals; this is a really basic everyday machinery that helps animals survive," Shohat-Ophir explained. "Drugs of abuse use the same systems in the brain that are used to process natural rewards. This allows us to use simple model organisms to study aspects of drug addiction, including the interplay between natural and drug rewards and the connection between experience and the mechanisms that underlie the risk to develop drug addiction."

Studying the sex lives of fruit flies is, surprisingly, not new. Last summer, a team from the U.S. Department of Agriculture's Agricultural Research Service, Hebrew University of Jerusalem and the Israel Agricultural Research Organization discovered a pheromone that female insects use to signal males when they're in the mood.

So there are lots of lessons to be learned here – especially that biology class is more than just dissecting frogs.

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Fruit flies have orgasms – and, apparently, they’re amazing
In bizarre research project, scientists at Bar Ilan University also discover why some fruit flies avoid getting drunk.