Biologists are calling for urgent nationwide action to prevent venomous fire ants from infesting Japan after the highly invasive species was spotted at several major ports, including Tokyo.
“Japan needs to fight the insects as a national campaign,” said Takahiro Murakami, an associate professor of behavioral biology at Kyushu University. “The government must implement an effective eradication program with the cooperation of the international community.
“If left uncontrolled, the country will go through what the United States and some other countries have experienced.”
Murakami said more than half the residents of some affected areas in the U.S. have been stung by the pests, which cause some ¥500 billion ($4.4 billion) in economic damage in that country every year.
Koichi Goka, head of the National Institute for Environmental Studies’ Center for Environmental Biology and Ecosystem Studies, said fire ants, native to South America, have already spread to more than 10 countries.
He said the damage is particularly serious in the U.S., Australia, China and Taiwan.
The insects made headlines in Japan after first being discovered in May in a container that arrived at Kobe port from Nansha port in Guangzhou, eastern China.
They have since been spotted at several other ports, including Nagoya, Osaka and Tokyo.
Making the situation more serious is the fact that queen ants, known to be extremely fertile, were found in Osaka and Kobe.
Shigeto Dobata, an assistant professor of insect ecology at Kyoto University, warned that queen fire ants can lay more than 1,000 eggs a day and that once they build a colony, the number will increase dramatically.
“It is crucial to block them from entering at an early stage. It would be extremely difficult to exterminate them once they take root,” he said.
No fire ant eggs or anthills have been found so far in Japan.
An Environment Ministry official said the ants may be breeding in Japan, but their settlement is believed to be at an early stage, as the formation of a hill takes about two years.
There have been no reports so far of anyone being stung.
The Land, Infrastructure, Transport and Tourism Ministry has urged local governments to carry out intense extermination measures at 63 ports with regular cargo shipments from China. The ministry has also called for similar measures at 870 other ports if they accept any container cargo from China.
The Environment Ministry and related ministries discussed steps in early July on fire ant control and underlined the importance of inspection and extermination at ports.
Environment Minister Koichi Yamamoto said Friday his ministry plans to expand its monitoring areas at Kobe, Nagoya, Osaka and Tokyo ports to a 2-km radius.
The Environment Ministry has decided to plant poison bait at those four and other ports where cargo ships from Nansha port arrive on a regular basis.
Officials of Nagoya port said they examine each cargo container for alien species but did not rule out the possibility that tiny insects may have escaped notice.
“Many containers are arriving from China and the U.S. every day. You cannot halt trade to prevent their invasion,” an official of the Nagoya port management association said. “The association does not have a specific department dealing with alien species. We have no other choice than to follow measures of the central and prefectural governments.”
The reddish-brown ants with a blackish-red belly range from 2.5 to 6 mm in size. Their stings can cause severe allergic reactions such as trouble breathing, pains like burns, and occasionally death.
If you are stung, you should lie down for 20 to 30 minutes and seek medical attention if the pain doesn’t subside. If you spot the ants, call the local municipal office or the nearest branch of the Environment Ministry.
Fire ants build dome-shaped mounds that can measure 25 to 60 cm in diameter in open fields such as parks and farmland.
Kyushu University’s Murakami said he was once stung by a fire ant when he was conducting field research on anthills in Taiwan in 2010.
“About 30 minutes after the sting, I started suffering nausea, hand tremors and impaired vision,” he said. “After lying down for about half an hour, the symptoms thankfully subsided.”
Australia, where fire ant colonies were first found around 2001, failed to prevent infestation and spent close to ¥29 billion over the next 15 years on eradication efforts, whereas New Zealand successfully eradicated them in a ¥120 million program using poison bait, according to Murakami.
New Zealand designated areas of 1 km around ant colonies as danger zones, planting poison bait and monitoring them for two years, he said.
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