Venomous and highly invasive fire ants have been found at Osaka port, with the first confirmation of a queen ant in the country, the Environment Ministry said.
The discovery is serious as queen ants can lay over 1,000 eggs a day. While no eggs have been found, the ministry is looking into whether the ants have built a nest.
The discovery, announced Tuesday, came during a probe conducted after another venomous alien ant species was found in a container that had reached a warehouse in Suminoe Ward in the city of Osaka on Thursday. The container had been shipped from Hong Kong.
A cluster of fire ants was found Friday in an asphalt crack at Osaka port. After killing them with pesticide, workers retrieved about 10 dead ants. On Monday, roughly 50 more were retrieved, including a queen, according to the ministry. The ministry estimates there were over 100 fire ants at the site.
Tuesday’s announcement prompted the Land, Infrastructure, Transport and Tourism Ministry to call for extermination measures at 63 ports with regular cargo shipments from China. The ministry called for similar measures at 870 other ports if they accept container cargo from China.
The 63 ports include Hakodate in Hokkaido, Yokohama, Nagoya, Osaka, Hiroshima as well as Hakata in Fukuoka Prefecture.
“It is crucial to block them from entering at an early stage,” said Shigeto Dobata, assistant professor of insect ecology at Kyoto University. “It would be extremely difficult to exterminate them once they take root,”
The reddish brown ants with a blackish-red belly, ranging from 2.5 to 6 mm in length, are known for a sting that can cause anaphylaxis, a severe allergic reaction, including breathing problems.
In Japan, they were first discovered in May in a container that arrived at Kobe port and was unloaded in Amagasaki, Hyogo Prefecture, which borders the city of Osaka.
They have since been found at Kobe port and Nagoya port in Yatomi, Aichi Prefecture, in containers that had come from Guangzhou, China.
The ants are native to South America.