Fruit flies use alcohol as a drug to kill parasites

Feb 16, 2012
Alcoholic drinks aren’t generally put into the category of health food, but in some cases they might be just the cure for nasty parasites. That’s according to a study published online on Feb. 16 in Current Biology, a Cell Press publication, showing that fruit flies will actually seek out alcohol to kill off blood-borne parasitic wasps living within them. Credit: Milan et al., Current Biology

Fruit flies infected with a blood-borne parasite consume alcohol to self-medicate, a behavior that greatly increases their survival rate, an Emory University study finds.

"We believe our results are the first to show that can have a protective effect against infectious disease, and in particular against blood-borne parasites," says Todd Schlenke, the evolutionary who led the research.

"It may be that fruit flies are uniquely adapted to using alcohol as medicine," he adds, "but our data raise an important question: Could other organisms, perhaps even humans, control blood-borne parasites through high doses of alcohol?"

is publishing the study, co-authored by Emory graduate student Neil Milan and undergraduate student Balint Kacsoh.

The results add to the growing body of evidence that some animals know how to use toxic substances found in nature as medicine.

, the common fruit fly that swirls around browning bananas in your kitchen, is an important biological . The Schlenke lab uses D. melanogaster to study how immune systems adapt to pathogens.

The eat the rot, or fungi and bacteria, that grows on overripe, fermenting fruit. "They're essentially living in booze," Schlenke says. "The amount of alcohol in their natural habitat can range from 5 to 15 percent. Imagine if everything that you ate and drank all day long was 5-percent alcohol. We wouldn't be able to live like that, but fruit flies are really good at detoxifying alcohol."

Tiny, endoparasitoid wasps are major killers of fruit flies. The wasps inject their eggs inside the fruit fly larvae, along with venom that aims to suppress their hosts' . If the venom is effective enough, the wasp egg hatches, and the wasp larva begins to eat the fruit fly larva from the inside out. Eventually, an adult wasp emerges from the remains of the fruit fly pupa.

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Alcoholic drinks aren’t generally put into the category of health food, but in some cases they might be just the cure for nasty parasites. That’s according to a study published online on Feb. 16 in Current Biology, a Cell Press publication, showing that fruit flies will actually seek out alcohol to kill off blood-borne parasitic wasps living within them. Credit: Milan et al., Current Biology

Some fruit flies, however, can overcome the effects of wasp venom and mount an immune response against wasp eggs. The blood cells in these fly larvae swarm over the wasp eggs and release nasty chemicals to kill them, allowing the fruit fly larvae to grow into adults.

"A constant co-evolutionary battle is going on between the immune systems of the flies and the venoms of the wasps," Schlenke says. "Any new mechanism of defense that protects flies from wasps will tend to spread through fly populations by natural selection."

Schlenke wondered if the fruit flies could be tapping the toxic effects of alcohol in their to fight off wasps.

To test the theory, the researchers used a bisected petri dish filled with the yeast that fruit flies are normally fed in a lab environment. The yeast on one side of the dish was mixed with 6 percent alcohol, while the yeast on the other side remained alcohol-free. The researchers then released fruit fly larvae into the dish, allowing them to freely move to either side.

After 24 hours, 80 percent of the fruit fly larvae that were infected with wasps were on the alcohol side of the dish, while only 30 percent of the non-infected fruit fly larvae were on the alcohol side.

"The strength of the result was surprising," Schlenke says. "The infected fruit flies really do seem to purposely consume alcohol, and the alcohol consumption correlates to much higher survival rates."

Infected that consumed alcohol beat out the wasps in about 60 percent of the cases, compared to a 0 percent survival rate for fruit fly controls that fed on plain yeast.

"The wasps aren't as good as the flies at handling alcohol," Schlenke says.

A developing wasp knocked out within an alcohol-consuming fly larva dies in a particularly horrible way, he adds. "The wasp's internal organs disperse and appear to be ejected out of its anus. It's an unusual phenotype that we haven't seen in our wasps before," Schlenke says.

The lab repeated the experiment using another species of wasp that specializes in laying its eggs in D. melanogaster, rather than the generalist wasp used previously. Again, 80 percent of the infected flies wound up on the alcohol side of the dish, while only 30 percent of the uninfected flies did. But the alcohol diet was far less effective against the specialist wasps, killing them in only 10 percent of the cases.

"You would expect this kind of result," Schlenke says, "since the generalist wasp species can attack plenty of other flies, but the specialist are under strong pressure to adapt to the alcohol-infused habitat of D. melanogaster."

The researchers hope that their data will lead to more studies of how alcohol may control pathogens in other organisms, including humans.

"Although many studies in humans have shown decreased immune function in chronic consumers of alcohol, little attempt has been made to assay any beneficial effect of acute or moderate use on parasite mortality or overall host fitness following infection," Schlenke says.

Explore further: Danish museum discovers unique gift from Charles Darwin

More information: Milan et al.: “Alcohol Consumption As Self-Medication Against Blood-Borne Parasites In The Fruitfly.” DOI:10.1016/j.cub.2012.01.045

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User comments : 12

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kaasinees
0.8 / 5 (25) Feb 16, 2012
One glass of wine or apple cider is very healthy "food". This is widely known, in fact doctors recommend it to heart patients.
Sean_W
1.8 / 5 (5) Feb 16, 2012
Can I use it as a preventative against parasites?
Sean_W
1 / 5 (3) Feb 16, 2012
One glass of wine or apple cider is very healthy "food". This is widely known, in fact doctors recommend it to heart patients.


I know a doctor who says "Red wine for health: two out of ten doctors recommend it." Obviously he was one of the two.
kaasinees
0.7 / 5 (24) Feb 16, 2012
One glass of wine or apple cider is very healthy "food". This is widely known, in fact doctors recommend it to heart patients.


I know a doctor who says "Red wine for health: two out of ten doctors recommend it." Obviously he was one of the two.

Obviously 4/5 doctors rather prescribe drugs that do exactly the same thing as red wine because they make money from it.
physpuppy
1 / 5 (1) Feb 16, 2012
kaasinees:
Obviously 4/5 doctors rather prescribe drugs that do exactly the same thing as red wine because they make money from it.


That does not make sense.

The doctor does not make money from the prescription - only from the visit.

"Get some red wine and come back in 4 weeks"
kaasinees
0.7 / 5 (25) Feb 16, 2012
That does not make sense.

http://www.npr.or...30730104

The doctor does not make money from the prescription - only from the visit.

No, you might want to rethink that.

"Get some red wine and come back in 4 weeks"

Of course that is a little bland, it is a diet suggestion for heart patients.
RazorsEdge
not rated yet Feb 16, 2012
One glass of wine or apple cider is very healthy "food". This is widely known, in fact doctors recommend it to heart patients.


I know a doctor who says "Red wine for health: two out of ten doctors recommend it." Obviously he was one of the two.


Red wine researcher accused of falsifying data
http://medicalxpr...ing.html
Smashin_Z_1885
3.7 / 5 (3) Feb 17, 2012
Yeah, so true, most doctors are interested in making money off the sale of pharmaceutical chemicals. However, Red Wine is proven to be healthy, as well as full-bodied and highly hopped beers. Cannabis is also a good example of a superior plant medication that is completely non-toxic to humans.
Kingtronics
not rated yet Feb 17, 2012
I know red and white wine are good for health.
Sinister1811
2 / 5 (12) Feb 17, 2012
So does this mean that those who drink have no parasites? lol
antialias_physorg
3.7 / 5 (3) Feb 17, 2012
Can I use it as a preventative against parasites?

One of the reasons why beer/wine was so popular in the middle ages. With largely unsanitary conditions water sources (often full of bacteria and parasites) alcoholic beverages provided a modicum of safety against that. Beer being much cheaper than wine it was the drink of choice for the general population.

So does this mean that those who drink have no parasites?

Only those that are resistant against alcohol to some extent. But with potable water being much safer today no one should have parasites unless they somehow get into contact with them through tainted food.
Skultch
3 / 5 (2) Feb 17, 2012
Man, this article is so full of awesome!! Insects self-medicating. Melanogaster? What a sweet name for a fly! The way those wasps die?!? And best of all, justification for my beer obsession!! YAY! :D