When it comes to eating and drinking, you are not even as good as them.

Spider? Drinking?

Whose research is so bizarre? It turns out to be Dr. Yu Guocheng from Hubei University.

The alcohol that spiders drink is not vodka or whiskey, but the product of natural fermentation of fruits . Alcohol is produced when food is fermented by yeast, or when overripe fruits and dead branches and leaves rot.

Yeast colonies in a petri dish. Image source: Wikipedia

Alcohol is very common in nature and in human life. For most animals, it is also a central nervous system modulator that does not require any receptors - in other words, alcohol affects the nerves of humans and most other animals equally.

People get drunk when they drink, and animals do too, and many animals have no resistance to alcohol . For example, both adult and larvae of fruit flies like alcohol at a certain concentration, because alcohol usually indicates the presence of their favorite food, sugar .

Alcohol can affect the behavior of animals . When bees "drink" 20% alcohol, their aggressiveness will be maximized.

So what effect does alcohol have on spiders? Dr. Yu and his research team conducted an experiment to answer this question.

The subject of the experiment is the Myrmarachne gisti, a carnivorous ant spider that loves to eat fruit flies .

A is male and B is female.

Ant spiders are jumping spiders, so named because they resemble ants in both appearance and behavior. This Batesian mimicry provides them with good protection, allowing them to be found in almost all tropical and temperate terrestrial habitats .

Do different ant spiders all look like ants? Image source: Yoshiaki Hashimoto et al. Scientific Reports (2020)

In these habitats, spider ants are often exposed to alcohol produced by fermenting fruits. Have they adapted to the presence of alcohol? Will they further develop a "love " for it?

Dr. Yu’s team proposed the following hypothesis:

1. The spider has a strong preference for certain concentrations of alcohol and avoids other concentrations of alcohol;

2. When they were exposed to their preferred alcohol concentration, they had a higher predation rate.

To explore this question, Dr. Yu's team first set up a maze selection experiment , as shown in the figure below. It is divided into three chambers, with the Ji ant spider placed in the middle, and different concentrations of alcohol and water were placed on both sides. After the Ji ant spiders were adapted to the chambers, they began to make choices. After five minutes, the time the spiders spent in the chambers on both sides and in the middle was counted.

The picture shows the spider selection device. A total of 640 Ji ant spiders collected from Wuhan were used in the experiment, including 325 female spiders and 315 male spiders, all of which were collected from the subadult stage and raised to sexual maturity using the same breeding plan.

The results showed that the spider had a significant preference for alcohol concentrations of 20%-35% , but showed a significant avoidance of alcohol concentrations above 45%.

And the preference of Ji Ant Spiders for alcohol concentration does show gender differences . According to the data, females prefer 20%-30% alcohol, while males like something stronger - they prefer 30%-35% alcohol.

When "drinking", spiders of different sexes have different choices. According to the authors of the paper, this is not a statistically significant difference, but it is still an interesting phenomenon.

Whether male or female, 30% alcohol is the favorite of the ant spider. Why do they prefer this concentration of alcohol? Is it because this concentration of alcohol usually leads to more prey?

To answer this question, Dr. Yu's team designed a similar choice experiment using fruit flies , a common prey of ant spiders, and found that fruit flies also like the 30% concentration of alcohol that ant spiders like!

Fruit fly: "Do you know the difference between drinking wine and drinking water? The more you drink wine, the warmer it gets. The more you drink water, the colder it gets."

The alcohol concentration that the ant spider likes happens to be the same as that of its prey , which seems to explain why the ant spider prefers this concentration of alcohol.

However, alcohol is a non-specific neuromodulator after all. Can spiders still hunt normally if they are "drunk"?

Dr. Yu’s team further designed the following experiments:

In the two chambers, one was filled with 200 microliters of 30% alcohol, and the other was filled with the same volume of water as a control. Then a Ji Ant spider and two flightless Drosophila melanogaster (mutants) were placed, and the spider's predation on the fruit flies was recorded. The timer started when the spider's front middle eye targeted the fruit fly.

The results of the experiment showed that 30% alcohol had no effect on the time spent watching and capturing prey, but the first-time success rate of female spiders in the 30% alcohol environment was significantly lower than that in the control group.

Ant spiders performed more predatory behaviors under alcohol conditions, but for female spiders, the success rate was significantly reduced, which is a case of "beauty can easily make people drunk."

In short, the research of Dr. Yu's team shows that perhaps, at least in the minds of this kind of spiders, alcohol is no longer just alcohol, but has become a signal for dinner. After all, the delicious fruit flies love alcohol so passionately.

Fruit fly: "It's time to eat!" Ant spider: "Hey, it's time for me to eat too!"

Source: WeChat official account of "National Wine Geography"

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