domingo, 25 de agosto de 2013

Kobe in struggle to fight off invasion of Argentine ants

By KOICHI HOTTA/ Staff Writer
August 25, 2013
An Argentine ant (Provided by Japan Wildlife Research Center)
Argentine ants march in procession in Kita Park on Port Island in Kobe’s Chuo Ward on Aug. 9. (Koichi Hotta)
KOBE--At a restaurant along a main road on Port Island in Chuo Ward here, a steady procession of alien Argentine ants could be seen marching near the entrance and parking lot.

Those ants enter my restaurant three or four times a year. Though I spray a chemical agent, I cannot prevent them from coming into my outlet,” the manager of the restaurant, who noticed the ants in his kitchen for the first time in 2008, said in mid-August.

Argentine ants, an alien species that destroys the natural ecosystem by expelling indigenous ants, have invaded various parts of Kobe and are infesting other prefectures.

They were confirmed for the first time in 1999 in Port Island, an artificial island in Kobe Port. Recently, however, they have also been confirmed in commercial areas in the central part of Kobe and residential areas in the suburbs.

If Argentine ants take root, it will be almost impossible to eradicate them," said Mamiko Ozaki, professor of biology at Kobe University’s Graduate School of Science. "If you take measures sooner, it is better.

Argentine ants, which are native to South America, are 2.5 to 3 centimeters long and brown colored. Though they are not poisonous, they have strong reproductive powers as several queen ants are living in one nest.

According to the Environment Ministry, Argentine ants were discovered in Japan for the first time in 1993 in Hatsukaichi, Hiroshima Prefecture. At present, they are confirmed in 12 prefectures, including Tokyo, Kanagawa, Osaka and Kyoto.

Argentine ants move more quickly than indigenous ants. They have been reported to be entering homes and collecting around food, and even infesting sleeping areas, preventing occupants from sleeping soundly. In one case, the procession of ants reached the eighth floor of an apartment building.

Local governments in various parts of Japan have started programs to eradicate them. Unlike indigenous ants, however, Argentine ants form a super colony, which means that ants of different nests live together and, as a result, many nests are connected. Therefore, eradication is extremely difficult.

Since 2009, the city government of Tahara in Aichi Prefecture has been engaged in eradicating Argentine ants in areas totaling about 90 hectares, including their habitats, in cooperation with local residents.

However, an official of the city government said, “We have no prospect (of eradicating them completely).

Meanwhile, the Kobe city government has yet to embark on eradication efforts.

We have not received concrete complaints from our citizens (against Argentine ants),” said an official of the city government’s living and sanitation section.

However, the ants' habitat is gradually expanding. According to a survey conducted by the Environment Ministry in November 2012, they were confirmed not only on Port Island but also in commercial areas and the Meriken Park, near the bustling Motomachi area. They were even found in a wharf near Suma Kaihin Park in Suma Ward, about seven kilometers west of the central area, and some residential districts in the ward.

In the spring, the Environment Ministry started eradication work in areas around Suma Kaihin Park on an experimental basis, saying, “There is a possibility that the habitats will spread.

The Kobe city government has also said that it recognizes that Argentine ants are troublesome, because an eradication method for them has yet to be established.

First of all, we want to ask our citizens to give us information on their habitats by showing the characteristics of Argentine ants in leaflets and on our city government website,” said the city government official.
By KOICHI HOTTA/ Staff Writer

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