Alcohol makes male fruit flies more attractive

Male fruit flies that drink alcohol become more attractive to females, a new study finds.

Adding alcohol to their food boosts the release of chemicals that attract females. This leads to higher mating success for the males.

Fruit flies, or Drosophila melanogaster, are often found near food waste. They feed on rotting fruit, which produces alcohol over time.

Scientists have studied why these flies are attracted to alcohol and its effects. Previous research suggested they seek euphoria or substitute mating highs when rejected by females.

Bill Hansson, study author and head of the Department of Evolutionary Neuroethology at the Max Planck Institute, offers a different view. He believes drinking alcohol gives flies a reproductive advantage.

"We don't think flies drink alcohol because they are depressed," he stated.

He explained that the attraction to carbohydrates, yeast in rotting fruit, and alcohol is interconnected.

In this study, alcohol—especially methanol—increased males' production of pheromones. These chemical signals made them more appealing to females.

Pheromones influence the behavior of other individuals in the same species. Males were particularly drawn to alcohol if they had never mated before.

The research also revealed that three neural circuits in the fly's brain control its response to smelling alcohol. Two circuits attract males to small amounts of alcohol while a third circuit deters them from excessive amounts.

Since alcohol is toxic, flies must weigh risks against benefits when drinking it. They balance attraction signals with aversion signals.

"This means that flies can enjoy the benefits of drinking without risking intoxication," said lead author Ian Keesey from the University of Nebraska.

Researchers used various methods for their investigations. These included imaging techniques for visualizing processes in the fly brain and chemical analyses of environmental odors.

The findings are published in the journal Science Advances.