Study unlocks secret of how fruit flies choose fruit with just the right amount of ethanol

Dec 10, 2013 by Bob Yirka report
This image shows a 0.1 x 0.03 inch (2.5 x 0.8 mm) small Drosophila melanogaster fly. Image: Wikimedia Commons

(Phys.org) —Researchers from the University of California working with a team at Howard Hughes Medical Institute in Virginia, have discovered how it is that fruit flies are able to lay their eggs in rotting fruit that has just the right amount of ethanol in it to promote healthy young. In their paper published in Proceedings of the National Academy of Sciences, the team describes how they found clusters of neurons in the adult flies' brains that responded differently to different levels of ethanol.

Fruit fllies are notorious for showing up just as begins to rot. Prior research has found they are able to smell the from a great distance and that the flies both eat the rotting fruit and use it as a repository for their . In this new effort, the researchers have found that the flies are also able to determine the level of ethanol in the fruit and to move on if it's not just right for the best development of their offspring. Too little ethanol, the researchers report, results in too-heavy offspring that have difficulty flying. Too much ethanol causes a delay in development which reduces their chances of reproducing. The right amount is apparently 5%—about the same as beer.

To ascertain if the fruit is right for rearing little ones, the adult female relies on clusters of in its brain, the team found, that actually work against one another. All of the neurons release dopamine, but the types of neurons differ in response to ethanol. One type causes the fly to seek it out, the other to avoid it—or at least too much of it. Thus, one group of neurons cause the mom–to-be to seek out fruit with ethanol in it, while another causes her to keep on moving if the stimulation is too strong. When the level is just right, she lays her eggs.

As a follow-up, the research team also traced the path of brain stimulation as ethanol was breathed in. They found that some regions of the brain that responded to stimulation got busy, while at the same time other regions that are believed to be involved in decision-making and memory lit up as well. This suggests that the flies were drawn in by the pleasurable aroma of ethanol, but then used logic to decide if the levels were right for baby-raising.

Explore further: Those fruit flies are pickier than you think

More information: Competing dopamine neurons drive oviposition choice for ethanol in Drosophila, PNAS, Published online before print December 9, 2013, DOI: 10.1073/pnas.1320208110

Abstract
The neural circuits that mediate behavioral choice evaluate and integrate information from the environment with internal demands and then initiate a behavioral response. Even circuits that support simple decisions remain poorly understood. In Drosophila melanogaster, oviposition on a substrate containing ethanol enhances fitness; however, little is known about the neural mechanisms mediating this important choice behavior. Here, we characterize the neural modulation of this simple choice and show that distinct subsets of dopaminergic neurons compete to either enhance or inhibit egg-laying preference for ethanol-containing food. Moreover, activity in α′β′ neurons of the mushroom body and a subset of ellipsoid body ring neurons (R2) is required for this choice. We propose a model where competing dopaminergic systems modulate oviposition preference to adjust to changes in natural oviposition substrates.

Related Stories

Alcoholic fly larvae need fix for learning

Nov 29, 2012

Fly larvae fed on alcohol-spiked food for a period of days grow dependent on those spirits for learning. The findings, reported in Current Biology on November 29, show how overuse of alcohol can produce lastin ...

Those fruit flies are pickier than you think

Dec 05, 2013

On your kitchen counter, it might seem as though fruit flies will show up for just about any type of fruit you leave around for them. But when given a choice about where to lay their eggs, those flies will ...

Fruit flies with better sex lives live longer

Nov 28, 2013

Sex may in fact be one of the secrets to good health, youth and a longer life – at least for fruit flies – suggests a new University of Michigan study that appears in the journal Science.

Recommended for you

Male monkey filmed caring for dying mate (w/ Video)

Apr 18, 2014

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Orchid named after UC Riverside researcher

Apr 17, 2014

One day about eight years ago, Katia Silvera, a postdoctoral scholar at the University of California, Riverside, and her father were on a field trip in a mountainous area in central Panama when they stumbled ...

In sex-reversed cave insects, females have the penises

Apr 17, 2014

Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but re ...

Fear of the cuckoo mafia

Apr 17, 2014

If a restaurant owner fails to pay the protection money demanded of him, he can expect his premises to be trashed. Warnings like these are seldom required, however, as fear of the consequences is enough to ...

User comments : 0

More news stories

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Making graphene in your kitchen

Graphene has been touted as a wonder material—the world's thinnest substance, but super-strong. Now scientists say it is so easy to make you could produce some in your kitchen.