If you get bitten, you will go into coma and shock! Some people have died from this. If you see it, please stay away immediately!

It is summer now. In southern my country, a kind of small red ant is causing trouble for people. Many people have been bitten recently, and there are even some serious cases. For example, a man who was fishing in Guangdong fell into a coma after being bitten. Fortunately, his fellow enthusiasts rushed him to the hospital.

The picture comes from a screenshot of Weibo

Why are these little ants so powerful? Where do they come from? And how can we protect ourselves from them?

It is not a native ant

These little red ants are called red fire ants (Solenopsis invicta). They are not native to my country, but are listed among the 100 most destructive invasive species by the World Conservation Union (IUCN).

Large and small worker ants and winged reproductive ants of red fire ants Photo by Liu Yanming

The origin of the red fire ant is in the Paraguay River Basin in South America. It was probably introduced to Mobile, Alabama, North America by shipping around 1918. It was not until around 1930 that Americans noticed this foreign ant and once identified it as the cruel fire ant (Solenopsis saevissima).

At first, the "violent fire ants" did not receive enough attention. About 20 years later, the spread of the "violent fire ants" made Americans taste the bitter fruit, so they started a vigorous campaign of pesticide control, but it ended in failure and caused serious pesticide pollution, which directly led to the publication of the famous environmental protection book "Silent Spring".

People gradually realized that the identification of the "brutal fire ant" was a bit problematic and it might be another species. In 1972, formicologist Williams Buren named it a new species, which is what we call the red fire ant today. Buren gave it the nickname "invicta", which means "invincible, unconquerable". Later facts proved that professionals are often foresighted in their own fields.

Also in the 1970s, multi-queen nests of red fire ants were reported in the United States. In such nests, there is no longer only one queen laying eggs, but hundreds of queens laying eggs. This is a major change in the invasion of red fire ants. It is not clear whether it evolved independently in the United States or was introduced from South America. The multi-queen nests have become larger, up to hundreds of thousands of ants, and more aggressive.

Red fire ants emerge from their nests. Photo by Liu Yanming

Records of the invasion of red fire ants in my country can be traced back to at least 2004, when the red fire ant colony in Wuchuan, Guangdong Province had grown to a large scale, and many people had been bitten, and even in Taiwan at that time, there were records of people being bitten to death. In 2008, Professor Lu Yongyue and others speculated based on a research model that the red fire ants may have been lurking in mainland my country for 16 years, and inferred that the initial invasion site was probably in Shenzhen, one of my country's most important foreign trade ports, in April 1995.

Be careful not to get bitten

The arrival of the red fire ants has brought serious damage to my country's native ecosystem. According to statistics, in the areas invaded by the red fire ants, the species richness of arthropods, including native ants, has decreased by 40%, which is a considerable proportion.

Vertebrates have also been affected. The venom of red fire ants is much more effective against small animals than against humans, and at least 22 species of birds, one amphibian and 18 lizards are known to have been affected by the spread of red fire ants.

Plants are also victims. Red fire ants not only eat plant sprouts and fruits, but also move and eat plant seeds, changing the ratio and growth distribution of seed plants, causing serious imbalance in the local natural ecology. The activities of red fire ants also change the physical and chemical properties of the surface soil, thus affecting the entire surface soil ecology.

At the same time, red fire ants have also seriously disrupted production and life. Not only have agricultural production and power equipment been affected, but people have also been stung. Since the venom of red fire ants is highly allergenic, allergic reactions caused by stings can cause serious consequences . Therefore, in areas where red fire ants are spreading, it has become very important to learn to identify and avoid direct contact with red fire ants.

The structure inside the red fire ant nest is like a honeycomb (Photo by Ran Hao)

It is indeed not easy to directly identify red fire ants. Even some major media frequently use incorrect ant pictures in their reports. However, there are still some characteristics that can serve as a basis for preliminary identification of red fire ants. On the one hand, they have a dark red body color. On the other hand, their nests usually have more than 4 types of worker ants of different sizes, which are enlarged and reduced in almost equal proportions.

Of course, this can still lead to misjudgment, especially not to confuse the native ants with big heads, the latter are our most reliable allies. In fact, in comparison, the nests of mature red fire ants are easier to identify. They are small mounds of earth protruding from the grass, with a honeycomb structure inside. A small disturbance will cause a large number of ants to swarm out.

The nest of red fire ants Photographed by Ran Hao

Generally speaking, red fire ants appear in environments with a lot of human activity, especially in artificial planting environments, such as grasslands, farmlands, etc. Artificially transplanted turf is an important channel for the spread of red fire ants and is also a major disaster area for red fire ants. Special attention should be paid to activities in these places.

In particular, be careful not to accidentally step on, sit on, or support yourself with your hands on the nest of red fire ants, which may cause serious harm to yourself. In places where the ecological environment is well protected, red fire ants usually do not occur. Native ants will patrol their own territories and eliminate the red fire ant breeding ants that sneak in. However, once these places are dug or repeatedly sprayed with pesticides, creating a "power vacuum" for native ants, red fire ants are likely to take advantage of the situation and form new populations.

Red fire ant nest outdoors Photo by Liu Yanming

What to do after a sting?

The most impressive thing about the red fire ant is its venom, which can be injected into the opponent through the sharp stinger at the tail. The venom of the red fire ant is mainly composed of piperidine alkaloids and a few water-soluble proteins. The severe pain after the sting mainly comes from the alkaloids, while the sensitization is likely related to the protein. After being stung by a red fire ant, almost everyone will have an itchy and painful reaction. Most people will have symptoms such as redness, swelling, and suppuration of the wound. About less than 1% of the stung people will have an allergic reaction. Usually, with proper care, the prognosis is good. If not handled in time, it may cause serious consequences.

To reduce infection, you can wash the wound with clean water or soapy water. If pustules occur, avoid breaking them. Pay attention to the hygiene of the wound. If the wound is infected again, it will be troublesome. When the pain is severe, you can apply ice to relieve the pain; you can also use topical ointments containing steroids or oral antihistamines to relieve the symptoms of itching and swelling, but the above drugs must be used under the diagnosis and instructions of a doctor.

Special attention should be paid to possible allergic reactions. If you have systemic itching, urticaria, red and swollen face, difficulty breathing, chest pain, rapid heartbeat or other special physiological reactions, you must seek medical attention immediately to avoid danger. Especially laryngeal edema, which may cause suffocation and death. Some people with allergic constitutions can carry some anti-allergic drugs with them when they are active in areas where red fire ants occur. Take them in time after being stung to reduce the probability of danger.

Planning and production

Author: Ran Hao, Biodiversity Genomics Group, Kunming Institute of Zoology, Chinese Academy of Sciences

Reviewer: Huang Chengming, Researcher at the Institute of Zoology, Chinese Academy of Sciences

Planning丨Zhong Yanping

Editor: Zhong Yanping

Proofread by Xu Lailinlin

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