Japan tackles invasive fire ants in first colony found this year, in China shipment
- Aggressive fire ants rear their heads in Japan for the first time this year, underlining nation’s constant battle to keep invasive alien species at bay
- The first fire ants discovered in Japan were at ports in 2017, with the insects apparently entering via shipments from mainland China, Hong Kong and Southeast Asia
“There is no question that this is becoming a bigger problem every year,” said Dr Koichi Goka, head of the Invasive Species Research Team at the National Institute of Environmental Studies.
“The first fire ants were found in a cargo in 2017 and since then, virtually every month another colony is discovered at a port somewhere in Japan,” he said.
To date, there have been 110 cases reported to the authorities, he said, “but we have been fortunate to find them and quickly eradicate these colonies”.
A queen fire ant can produce as many as 1,600 eggs a day and the insects, which have a reputation for being aggressive, can grow up to 6mm long. Authorities in other countries have confirmed that their bite can cause anaphylactic shock and, in extreme cases, have been reported to have caused death in very young or elderly people.
There have been no reports of colonies beyond the immediate environs of ports, Goka said, but officials and port staff have been instructed to remain alert.
Scientists at the institute have developed a new insecticide to spray inside containers that is now available at every port in Japan. They have also created a bait that contains pesticide.
The ants could cause a great deal of damage if a breeding colony entered a city environment.
“Most of Japan is too cold in the winter months for these ants, so we expect that they would try to nest in urban areas, taking advantage of the ‘heat islands’ created by homes and other buildings,” Goka said.
“They could thrive in that sort of environment, causing damage to structures and injuring people.”
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And if the larger and more aggressive insects entered the subtropical areas of southern Japan, such as Okinawa Prefecture, it is likely that they would quickly annihilate local ant species, Goka says.
“The entire ecosystem would undoubtedly suffer, and we are seeing that happening in parts of southern China where they are spreading today,” he said. “In some places, it looks like they cannot be stopped.”
Fire ants are just one of the threats to Japan’s native flora and fauna.
The National Institute of Environmental Studies’ website lists over 1,000 invasive species of plants and animals. Many have evaded quarantine controls and have since adapted to life in Japan, but some were imported as pets and then either escaped or were released by their owners.
In 2020, Goka’s agency confirmed that a species of cicada first found in central Japan in 2011 had arrived as eggs in broomstick shipments from China.
An example of an imported species that has adapted to its new habitat is the American raccoon, according to Goka.
“In the 1970s, there was a very popular television cartoon about a raccoon called Rascal and suddenly every family wanted a pet raccoon,” he said.
“The cartoon raccoon was very cute and hundreds were imported, but people quickly learned that they can be very aggressive, and they grow big very quickly.”
Unable to care for their pets, many people chose to simply release them, and their offspring are now a frequent sight in the suburbs of Japanese cities.
Similarly, black bass that were imported by an entrepreneur as a potential new food source did not appeal to the Japanese palate and were either released or escaped from fish farms. Large and aggressive, they have laid waste to the native species of fish that inhabited Lake Biwa, in central Japan, and other large bodies of fresh water across the country.
Snapping turtles – which can bite off a person’s finger – have similarly been dumped in suburban park ponds, along with American crayfish and bullfrogs. Countless civet cats, imported in the 1850s to be farmed for its fur, escaped and have since thrived in the wild and are blamed for damage to farmers’ crops.
Japan passed the Invasive Alien Species Act in June 2004 to stem the flood of foreign flora and fauna, but Kevin Short, a naturalist and former professor of cultural anthropology at Tokyo University of Information Sciences, says adaptive plants and animals will always get through.
“It is an unavoidable consequence of greater global trade and more containers coming into Japan from other parts of the world,” he said. “The best thing the authorities can do is to try to contain invasive species in areas close to ports until they can deal with them.
“Yes, they pose a threat to Japan’s biodiversity and ecosystems, but I do not think that is the greatest threat,” he added. “Ecosystems are resilient, and they are able to adapt to change, but if there are large numbers of fire ants or poisonous spiders, like redbacks that have been reported here already, then that poses a danger to people.”
Goka agrees that the challenges are huge.
“My fear is that if it is impossible to eradicate all invasive species, then Japan’s natural flora and fauna will ultimately be destroyed,” he said. “Inevitably, the same thing will happen across Asia and the rest of the world. Countries need to work with each other to limit the spread of these species and protect our domestic ecosystems.”
