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Why Do Fruit Flies Drink?

Yes, you read the title right. Fruit flies drink. Researchers have discovered that the common fruit fly actually prefer to feed on substances that have about 4 to 5 percent of alcohol.

Fruit flies like to self-medicate just as humans do. They rid their frustrations through the consumption of alcohol. Male flies prefer spiked food after being rejected by their mates. They then engage in sexual activity after getting drunk.

How Was This Discovered?

Todd Schlenke, a fruit fly biologist from Emory University had a habit of catching fruit flies in his backyard. He would keep them in a jar and sometimes even catch different species. (Source: Scientific American)

While he was observing the flies, he noticed a wasp crawling from one fly larva to another. The wasp was using its ovipositor to inject her eggs inside the fruit fly larvae. When the wasp eggs hatches, they consume the fly from the inside. This phenomenon truly fascinated Todd and he became obsessed with them (Source: Scientific American)

He started a study on fruit flies and wasps. He studied their behavior and was actually focusing on the wasps act of parasitism. (Source: Scientific American)

In the course of the study, Todd and his team exposed the fruit flies and wasps to alcohol. He had already presumed that the fruit flies would hold the alcohol better than the wasps, since they feed on all sorts of toxic things. (Source: Scientific American)

They placed the fruit flies and wasps in different levels of alcohol to see if they died. True enough to his hypothesis, Todd was able to confirm that fruit flies could deal with the highest concentration of alcohol. (Source: Scientific American)

How Do Drunken Fruit Flies Behave?

Now that we know fruit flies can tolerate the consumption of alcohol let’s talk about their behavior while they are in a drunken stupor.

You will be surprised to know that male fruit flies actually behave quite similarly to male humans. Chronic exposure to alcohol triggers hyper sexuality in fruit flies that make them chase after anything that have wings – and yes, other male fruit flies too. (Source: Nature)

According to Ulrike Heberlein, a neuroscientist from the University of California, like humans too, they are less coordinated when the concentration of ethanol in their body increases. They start to bump into walls and each other. (Source: Nature)

Do The Fruit Flies Intentionally Consume Alcohol to Get Drunk?

Apparently the answer to that question is yes. Fruit flies, very much like humans, like to self-soothe. They drink their sorrows away. (Source: NY Times)

When male fruit flies are subjected to a long tease followed by a rejection from a potential mate, they opt to consume food with alcohol. To test this theory, researchers from the University of California allowed male flies to mate freely with available virgin females. Whereas another group of male files were placed with a group of female flies who already mated and was not interested to mate again. (Source: NY Times)

After a couple of days, the flies in both groups were fed through glass tubes. Two tubes containing regular yeast and sugar, and the other two containing yeast, sugar, and 15% of alcohol. (Source: NY Times)

It was discovered that the rejected flies drank more of the spiked mixture compared to the flies that were able to mate successfully. (Source: NY Times)

Ulrike Heberlein said, “It’s the first time we have shown this link between a social experience that involves reward and a drug-related behavior” (Source: NY Times)

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