Fruit flies take on parasitic wasps with alcohol: Study

Fruit flies take on parasitic wasps with alcohol: Study


Fruit flies purposely seek out alcohol to kill parasitic wasps that live in their bloodstream, according to a Emory University study published Thursday in the journal Current Biology. According to a press release from Emory University, the use of alcohol increases the survival rate of fruit flies infected with a blood-borne parasite.

“We believe our results are the first to show that alcohol consumption can have a protective effect against infectious disease, and in particular against blood-borne parasites,” said Todd Schlenke, an assistant professor at Emory University, in a press release.

The study, titled Alcohol Consumption as Self-Medication against Blood-Borne Parasites in the Fruit Fly, was co-authored by Emory graduate student Neil Milan and undergraduate student Balint Kacsoh.

Fruit flies, which feed off of fermenting fruit, are “essentially living in booze,” according to Mr. Schlenke. “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,” the evolutionary geneticist posited.

Parasitic wasps are extremely deadly to fruit flies. The wasps place their eggs inside the fruit fly larvae, adding a small amount of immune-suppressing venom. If everything works in the wasp’s favor, the wasp emerges victorious. While many fruit flies succumb to the wasp venom, some fruit flies are able to kill off the wasp eggs with harmful chemicals.

The researchers found that environmental alcohol protects fruit flies from being parasitized by wasps. Researchers also found that imbibing alcohol kills internal wasps. Furthermore, researchers discovered that fruit flies seek out food with higher alcohol content when they are infected by parasitic wasps.

Researchers came to these conclusions by using a petri dish that was filled with yeast. One half of the petri dish was a 6 percent alcohol mixture and the other side was alcohol-free. The researchers allowed the fruit flies to move about the dish. After one day’s time, the researchers discovered that more of the infected fruit flies were on the alcohol side than non-infected fruit flies.

“The strength of the result was surprising,” Mr. Schlenke posited. “The infected fruit flies really do seem to purposely consume alcohol, and the alcohol consumption correlates to much higher survival rates,” he added.

However, using alcohol to kill off parasitic wasps comes with a risk. “If the alcohol level gets too high, they can’t break it down fast enough,” Mr. Schlenke posited to LiveScience.

The blood alcohol level of the fruit fries in the study maxed out at 0.02 percent. For comparison, a drunk driver has a blood alcohol level of 0.08 percent or higher.

“If you dissect open a fly that was fed alcohol food, the wasps were obviously dead and in a lot of cases the internal organs in the wasp larvae had fallen out the wasp’s anus,” Mr. Schlenke professed.

While the subjects of the study are extremely small, the study’s researchers believe that their data may have bigger implications in the world of humans.

“It may be that fruit flies are uniquely adapted to using alcohol as medicine,” Mr. Schlenke professed, adding “our data raise an important question: Could other organisms, perhaps even humans, control blood-borne parasites through high doses of alcohol?”

While alcohol’s ability to fight off parasites in humans may not be fully fleshed out, its impact on the human immune system is better understood. Evidence suggests that heavy alcohol consumption decreases the immune system’s ability to function. In fact, there may be a relationship between alcohol-related diseases such as liver disease and autoimmunity. Whether alcohol can kill parasites in humans is a question that is likely to be explored in future studies.