On the march

Luo said the number of counties in which the ants have been detected is 15 times higher than when they were first reported in China in 2004. Their strong reproductive ability, adaptability and low number of natural enemies are among the reasons they have spread so quickly.

"Each queen ant, with an average life span of seven years, can produce 100,000 to 250,000 eggs per year. Each ant nest can have dozens of queen ants, so they reproduce really fast," Luo added.

To ensure they have sufficient food, red fire ants attack and eat anything they like. They have adapted to different conditions in southern areas of China, except for virgin forests. The ants, which can be carried by birds and even humans, spread through grass-covered ground and plants, and on water, Luo said.

In the Pantanal region of South America, the world's largest tropical wetland area, where the ants originate, they are mainly contained by natural enemies, including 23 species of flies.

"When the ants arrived in China, there were no natural enemies to contain them, which allowed them to spread fast," Luo said.

Lu, from South China Agricultural University, said the main reason the ants have spread so rapidly in China is the failure to intercept their transmission routes. "About 80 percent to 90 percent of the fire ants spread through grassy areas, plants and flowers … This poses challenges to control work," he said.

Only having two or three workers from a county inspection and quarantine bureau is barely sufficient to monitor a high number of registered plant growers, he added, so cross-departmental cooperation is needed for effective prevention and control efforts.

Campaign launched

In March, the Ministry of Agriculture and Rural Affairs launched a campaign to combat red fire ants along with eight related authorities, including the Ministry of Housing, Ministry of Transportation, the National Health Commission and the National Forestry and Grassland Administration.

Lu said the campaign would help solve the problem.

"I proposed in a video conference with provincial housing and construction departments earlier this month the addition of one or two standards regarding project inspection work for red fire ants," he said, adding that this will improve the efficiency of control work.

A Ministry of Agriculture official said the campaign is expected to effectively contain the spread of red fire ants in three to five years, ensuring a stable increase in grain production and helping prevent the insects from biting and stinging people.

To date, 40 effective pesticides have been registered and new equipment such as drones and bait spreaders has been used for control work, the department said.

Some of the bait and technology used to catch the ants in parts of Guangdong and Fujian provinces and Guangxi Zhuang autonomous region has been successful in eradicating the pests.

"So far, bait is regarded as the best way to control these insects," Luo said.

China is expected to strengthen efforts to improve education and management related to the technology used to contain the ants, experts said.

During an inspection visit, Lu witnessed some county-level governments using the wrong way to get rid of the ants.

"They didn't know they were misusing the technology, or insisted on trying a less effective method," he said, adding that some authorities showed an incorrect photograph of a red fire ant when reporting on efforts to contain the insects.

Moreover, the public, especially farmers, who are more likely to encounter the ants, should be taught by professionals about the danger the insects pose and how they should protect themselves, Lu said.

He added that a popular science website in China once incorrectly claimed that only 3 percent of people were allergic to red fire ants. "Basically, 95 percent to 99 percent of people are allergic to the ants to some degree, although I believe 3 percent have a serious reaction if they are bitten or stung," he said.