Fruit flies show alcohol preference when hungry

In October 2026, a study published in Current Biology found that food-deprived fruit flies began to prefer alcohol earlier than those that were well-fed. The research, led by Karla Kaun at Brown University, suggests that hunger influences behavior through a learned association with alcohol, rather than directly measuring a feeling.

Learned preference for alcohol odor

The experiment involved training fruit flies through three learning sessions spaced fifty minutes apart. During these sessions, an odor was paired with alcohol vapors, while a second odor had no association. Hungry fruit flies were placed on a gel without nutrients, while well-fed ones received yeast.

Behavior change in a Y-shaped maze

After the learning sessions, the fruit flies were tested in a Y-shaped maze with about sixty insects per condition. Immediately after training, the insects avoided the odor linked to alcohol. However, after a few hours, they began to be attracted to it, with hungry flies showing this shift about three hours earlier than their well-fed counterparts.

Preference returns to normal over time

Twenty-four hours after the test, both hungry and well-fed fruit flies showed similar preferences for the alcohol-associated odor. This suggests that while hunger accelerates the shift in preference, it does not increase the final intensity of the preference.

Octopamine linked to the shift

The researchers identified a molecule called octopamine as being responsible for the speed of the shift in behavior. This molecule appears to play a role in how quickly the fruit flies change their preference for the alcohol-associated odor when they are hungry.