Glossary: "Red Imported Fire Ant"
In this issue, let's take a look at the "Red Imported Fire Ant".
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"Red Imported Fire Ant": A species of ant native to South America, it is a designated invasive alien species that has become a global problem due to its potent venom and aggressive nature. The name "fire ant" comes from the intense, burning pain felt when stung.
1. Ecology and Characteristics of the Red Imported Fire Ant
Body Length: A characteristic of worker ants is that their body length varies from 2.5mm to 6mm, even within the same colony.
Body Color: They are generally reddish-brown, with a darker, blackish-red abdomen. Their bodies have a shiny, glossy appearance.
Nest (Ant Mound): They prefer open, sunny areas and build dome-shaped "ant mounds" made of soil. Large mounds can reach up to 60cm in diameter and 50cm in height.
Behavior: They are extremely aggressive and will swarm and attack in groups if their nest is disturbed. They are omnivorous, feeding on insects, small animals, and plants.
Venom: They possess a stinger at the end of their abdomen, which they use to inject alkaloid venom. This venom causes intense pain and allergic reactions.
2. Dangers and Impact on the Human Body
The greatest danger of the red imported fire ant is the health damage caused by its venom.
Intense Pain and Swelling: When stung, an intense, burning pain like a fire burn occurs, followed by itching and blister-like swelling.
Anaphylactic Shock: If the allergic reaction to the venom is severe, it may cause anaphylactic shock. This is a life-threatening, serious condition involving symptoms such as difficulty breathing, a drop in blood pressure, and loss of consciousness. People with bee venom allergies or those who have been stung multiple times should be especially careful.
3. Current Situation and Countermeasures in Japan
In Japan, since they were first discovered at a port in Hyogo Prefecture in 2017, there have been successive reports of sightings at various ports and container yards.
Border Control Measures: Because they often enter Japan along with international cargo, the Ministry of the Environment and other agencies are focusing on strengthening monitoring, disinfection, and extermination at ports.
Concerns About Establishment: So far, there have been no confirmed cases of them becoming widely established within Japan, but if they were to become established, they could have a serious impact on ecosystems, people's lives, and agriculture.
Response Upon Discovery: Red imported fire ants are extremely dangerous, so if you find a suspicious ant or ant mound, never touch it with your bare hands, step on it, or destroy the nest. It is important to immediately exterminate them with commercially available insecticide or contact your local government or the Ministry of the Environment's consultation hotline.
4. How to Identify Them
Identifying red imported fire ants is difficult for anyone other than an expert, but please refer to the characteristics below and act with caution if you discover a suspicious ant.
A colony with individuals ranging from 2.5 to 6 mm in length, showing size variation
Body color is reddish-brown and shiny
They build large, dome-shaped mounds made of soil
Highly aggressive and will immediately attack in groups
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1. Reproductive and dispersal capabilities of the red imported fire ant
One of the threats posed by the red imported fire ant lies in its phenomenal reproductive and dispersal capabilities.
Queen ant: It is said that a queen ant lays over 1,000 eggs per day, and a single nest may contain multiple queen ants.
Budding: When a nest becomes large, a phenomenon called "budding" occurs, where some queen ants and worker ants leave the original nest to build a new one elsewhere. This allows the colony to expand over a wide area in a short period.
Movement: Through a "nuptial flight," where queen ants become winged ants and take flight, they can establish nests in new locations several kilometers away.
Formation of "rafts": In the event of floods or similar situations, the entire fire ant colony can interlock the bodies of worker ants to form an "ant raft," allowing them to move while drifting on the water surface. This creates the potential for them to spread over a wide area via waterways.
2. Details of venom components and effects on the human body
The venom of the red imported fire ant causes not only simple pain but also various biological reactions.
Main component of venom: The main component of the venom is "solenopsin," a type of alkaloid. This substance acts on the nervous system, causing intense pain and inflammation.
Formation of pustules: Within 1 to 2 days after being stung, white blisters containing pus (pustules) form on the affected area. If these are broken, it can lead to bacterial infection and may leave scars.
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Allergic reaction: Protein components in the venom act as allergens, triggering an immune response.
Mild: Hives or rashes
Severe: Anaphylactic shock, including throat swelling, difficulty breathing, loss of consciousness, and drop in blood pressure
Treatment: If stung, first wash the affected area with soap and cool it to reduce inflammation. If an allergic reaction is suspected, you must seek medical attention immediately.
3. Main entry routes into Japan and current status
Red imported fire ants did not reach Japan by crossing the ocean naturally; they have entered through human activity.
International cargo: The most primary entry route is by hitchhiking in containers and cargo transported by ship. They are often carried attached to wood, gardening supplies, soil, and automotive parts, in particular.
Ports: Discoveries have occurred one after another at ports that serve as hubs for international logistics, such as the Port of Kobe, Port of Nagoya, and Port of Tokyo. These ports are locations with a very high risk of entry because they collect cargo from overseas.
Temporary discovery: So far, most cases in Japan have been found at ports, adjacent container yards, or logistics facilities. These are often colonies that have entered temporarily with cargo, rather than having "established" themselves.
Concerns about establishment: Because red imported fire ants prefer warm climates, it has been pointed out that there is a possibility they could establish themselves in warm regions of Japan (especially Kyushu and the Pacific side of Honshu). While it is considered difficult for them to establish in regions with severe winter cold, there is a possibility that their habitat could move northward due to the effects of global warming.
By understanding these details, you can more deeply recognize the threat of red imported fire ants and take appropriate preventive measures and responses. If you discover a red imported fire ant, it is most important never to touch it with bare hands and to contact your local government or the Ministry of the Environment.