Because it had a few extra copies of its genes, it became the king of drinking!

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Author: Su Chengyu

Producer: China Science Expo

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Imagine if you were asked not to eat any solid food for the next seven days, and had no other drinks to choose from, and only had an 80% alcohol solution to accompany you, how would you change?

In the days that follow, you'll feel the alcohol burning your throat and stomach, and you may even pass out. Your liver will work like a machine, trying to break down the alcohol, while acetaldehyde (an intermediate product of alcohol metabolism) accumulates in your body, corroding your organs like a "poison."

In just one day, you may start to vomit, feel dizzy, and become confused. By the next day, your liver function may be seriously damaged. A week? Don't even think about it, because you will probably have collapsed long ago.

It sounds like a terrifying extreme challenge, but in the insect world, the Oriental wasp (Vespa orientalis) actually completed this "experiment" in an unimaginable way. The relevant research results were published in the Proceedings of the National Academy of Sciences (PNAS) in September 2024.

Paper results

(Image source: PNAS official website)

Oriental wasps can steal human alcoholic beverages

Vespa orientalis, also known as the Oriental hornet, is an insect of the family Vespidae in the order Hymenoptera. It is about 14-18 mm long, mainly brownish yellow in color, with distinct yellow stripes on its abdomen.

Oriental Wasp

(Image source: inaturalist)

Sofia Bouchebti is an animal behavioral ecologist who has focused on the adaptive relationship between insects and environmental stress for many years. Her research began during a field trip when she observed that Oriental wasps showed an unusual interest in rotting fruits and alcoholic beverages discarded by humans. "They seemed to not only tolerate these environments, but also benefit from them," Sofia recalled, "which was very unusual."

Insects' interest in fruit

(Image credit: Eran Levin)

Normally, most animals only ingest low concentrations of ethanol. Alcohol is high in calories, 7 calories per gram, nearly twice as high as sugar's 4 calories. It is also toxic to the body, and excessive intake may cause nervous system disorders or even death. The World Health Organization (WHO) clearly states that "there is no safe level of alcohol intake."

How much alcohol can the Oriental wasp drink?

In order to find out how much the Oriental wasp can drink, Sofia and her team designed an experiment. They prepared more than 2,000 Oriental wasps and European honey bees, and prepared sugar water solutions containing different concentrations of ethanol for them in the laboratory. The sugar water solution is a sweet wine with alcohol concentrations ranging from 1% to 80% made by adding ethanol solution to 50% sucrose solution in a certain proportion.

Scientists continued to observe their behavior and survival, initially thinking that 40% alcohol concentration would be enough to make them incapable of action or even die. But the result was that they not only survived, but also behaved more active than expected at 80% alcohol.

Experimental data showed that in an environment with an 80% ethanol concentration, the survival rate of wasps reached over 95%, and their nesting behavior (such as the speed and size of building a hive) was not significantly different from the control group (ethanol-free sugar water). Obviously, the high concentration of ethanol in sweet wine has little effect on their daily activities, and they can still work after drinking.

Oriental wasp worker bees have a strong tolerance to ethanol, and their survival rate is not significantly reduced even in a high concentration environment (80%).

(Image source: Document 1)

In contrast, European honey bees that also participated in the experiment could not withstand such a challenge. After consuming high-concentration sweet wine, the bees' behavior became extremely unstable, their wings trembled, and their movements became slow, as if they were covered with invisible shackles, and eventually died in large numbers within 24 hours.

Oriental wasps showed extremely strong tolerance to high concentrations of ethanol, while honey bees showed lower survival ability under similar conditions, indicating that there are significant differences in their metabolic mechanisms.

(Image source: Document 1)

Why is the Oriental wasp so good at drinking?

Scientists used a special marker, the "13C1-labeled ethanol" isotope. In simple terms, a "tracker" was added to the ethanol, so that the metabolic path of the ethanol in the wasp's body can be observed.

Scientists have found that in a high-concentration ethanol environment, the activity of alcohol dehydrogenase (NADP+) in wasps increases significantly. Alcohol dehydrogenase is a key enzyme responsible for breaking down ethanol. It first breaks down ethanol into acetaldehyde (an intermediate metabolite), which is then further converted into acetic acid (i.e., acetic acid), which eventually enters the body's metabolic cycle and becomes a harmless substance that can be used by the body. In particular, at an ethanol concentration of 80%, the activity of alcohol dehydrogenase increased by about 3 times compared to the low-concentration group.

Through research, scientists quickly found the answer - multiple copies of the gene. Scientists used the tblastn method to analyze the duplication of the gene of the ethanol metabolism enzyme in the Oriental wasp and other species of the genus Vespa.

tblastn is a bioinformatics tool based on BLAST (Basic Local Alignment Search Tool) that is used to search for regions that match specific protein sequences in nucleic acid sequence databases. Through sequence comparison analysis, scientists confirmed the phenomenon of multiple copies of the alcohol dehydrogenase gene, which are located on the same chromosome. All this is speculated to be caused by tandem duplication events.

Tandem duplication is a genomic recombination phenomenon, in which a DNA sequence of a gene is repeatedly copied and inserted into the original position, forming multiple consecutive gene copies. These gene copies are usually located on the same chromosome, close to each other, like "tandem", so they are called tandem duplications.

It is precisely because the Oriental hornet has several extra copies of the alcohol dehydrogenase gene that the rate of ethanol decomposition is greatly enhanced, which not only improves its tolerance to high-concentration ethanol, but also allows it to use it as a source of energy.

Oriental Wasp

(Image source: Wikipedia)

Insect genomes often contain multiple copies of genes, especially when faced with external environmental stress such as the use of insecticides or the accumulation of toxins in the environment. For example, the insecticide tolerance of cotton bollworm is directly related to the multiple copies of genes for anti-toxin enzymes (such as P450 enzymes or acetylcholinesterase) in its body.

Insects are more likely to adapt to environmental pressures through gene multiplication than other organisms because they reproduce quickly, have large populations, and mutations and gene multiplication are more likely to occur and persist in the population. In addition, insect genomes are relatively small and simple, which increases the incidence of gene multiplication events.

How does the Oriental wasp rank in terms of drinking ability?

According to existing research, tree shrews are considered to be the most adaptable vertebrates to ethanol intake, and they regularly consume food with ethanol concentrations up to 3.8% without obvious consequences in their natural habitat. However, under laboratory conditions, long-term intake of 10% ethanol concentrations can cause severe liver damage within 14 days.

Among invertebrates, fruit flies were previously considered the most vulnerable. Fruit flies do not show negative effects when they consume ethanol concentrations below 4%, but concentrations above this threshold significantly increase mortality. In contrast, oriental wasps can tolerate ethanol concentrations as high as 80% in experiments, which is extremely rare among other animals.

Research on Oriental wasps reveals the mechanism by which insects adapt to alcohol, as well as the complex relationship between genes, environmental pressure and evolution, which has triggered thinking about the genetic potential of human beings. By studying these "little monsters" hidden in nature, scientists are trying to uncover the secrets of alcohol metabolism and explore the trajectory of co-evolution of genes and the environment.

References:

1.Bouchebti S, Gershon Y, Gordin A, et al. Tolerance and efficient metabolization of extremely high ethanol concentrations by a social wasp[J]. Proceedings of the National Academy of Sciences, 2024, 121(44): e2410874121.