The fire ant， a creature measuring only 3 to 6 mm， recently caused a big stir in China. It has prompted a joint prevention and control drive by nine ministries as it has already caused a lot of harm that is difficult to control.
　　Officially referred to as the red imported fire ant（RIFA）， it is popularly known as “fire ant” for its ability to inflict painful bites and stings. Its Latin name， the Solenopsis invicta Buren， means “invincible ant.”
　　The insect has been identified as one of the world’s 100 worst invasive alien species by the International Union for Conservation of Nature.

Origins

　　Lu Yongyue， a professor with the RIFA Research Center at South China Agricultural University（SCAU）， in Guangzhou， Guangdong Province， has devoted the past decade of his career to researching the RIFA.
　　In September 2004， a staff member from the plant quarantine station in Wuchuan， Guangdong Province， spotted an ant harmful to people and decided to send a sample to the provincial plant quarantine station. The sample was then transferred to the department of entomology at SCAU. Three experts at the department， including Lu， were subsequently assigned to identify the insect.
　　After observation of the sample， onsite research and further analysis， the university’s expert team which then identified the insect as the RIFA. This was the first time the RIFA was confirmed to have entered the Chinese mainland.
　　These dark brown-reddish ants belong to an invasive species indigenous to Brazil， Paraguay， and Argentina.

　　The ant species spread to the U.S. in the 1930s and to islands in the Caribbean Sea from 1981. It crossed over the Pacific to invade Australia and New Zealand in 2001.
　　Lu Lihua， a researcher with the Plant Protection Research Institute of Guangdong Academy of Agricultural Sciences， told The Beijing News that the RIFA most probably spread to Wuchuan through imported garbage.
　　“At that time， imported plastic garbage was being processed in Wuchuan to make slippers. Research shows the DNA of the RIFA found in Wuchuan is identical to that of the RIFA in the U.S.，” Lu Lihua said.
　　In 2005， the Ministry of Agriculture formulated an emergency response plan for RIFA outbreaks， detailing four levels of responding measures.
　　In spite of the efforts， the insect has since spread to 12 provinces， autonomous regions and municipalities including Zhejiang， Jiangxi， Sichuan and Guizhou provinces plus Chongqing. 　　In March， nine ministries， including the Ministry of Agriculture and Rural Affairs （MARA） and the Ministry of Transport， issued a notice on strengthening the interception， prevention and control of the RIFA.
　　The notice required customs to enhance their inspection and quarantine of imported goods， especially saplings and logs from countries and regions that have the RIFA， and of crop seedlings and landscape greening plants from infested areas.
　　Following the issuance of the notice， the Guangdong provincial department of agriculture and rural affairs on April 2 announced its proposal to spend 40 million yuan （$6 million） on RIFA prevention and control this year.
　　The prevention and control measures targeting invasive species like the RIFA have been taken to the next level as China’s first-ever biosecurity law went into effect on April 15.
　　The law stipulated that MARA should work with other State Council departments to formulate a list of invasive species and strengthen their investigation， monitoring， forewarning， and control.

Damages

　　The ant thrives in warm and humid places with ample sunshine. For this very reason， they prefer the south of China to the north and are often found in parks， farmlands， and forests.
　　Lu Yongyue told Beijing Review that the RIFA can cause damage to over 50 plant species by eating their seeds， sprouts， roots and fruits. They can also shift the seeds， reducing their germination rate. In areas infected by the ants， the germination rate of corn and green bean seeds can drop by 14 and 7.4 percent， respectively.
　　Some areas are so seriously affected by the insect that farmland has to be entirely deserted. For instance， in 2008， large stretches of farmland in Huizhou， Guangdong Province， were abandoned due to a severe RIFA infestation. Planting recovered only after the pest was brought under control.
　　In addition to harming crops， the RIFA can also pose a risk to domestic poultry and livestock. For instance， several pig farms in Zengcheng District in Guangzhou once reported a RIFA infestation that caused over one fourth of the piglets and over 10 percent of adult pigs to be stung， subsequently stunting their growth.
　　The RIFA also threatens biodiversity and biosecurity. The insect can catch arthropods， causing a sharp decline in biodiversity and even resulting in the extinction of particular species.
　　Statistics show that in seriously infested areas， the number of earthworms can reduce by over 60 percent， causing soil hardening and acidification. In infested lychee farms， the number of indigenous ants can reduce by 70 to 80 percent. 　　The RIFA can also harm people’s health and even endanger their lives. If a mound is disturbed， thousands of worker ants will swarm out and sting anything in their path. Sting symptoms include burning and itching and an allergic reaction can occur if a person is hypersensitive to the stings， including flushing of the skin， the outbreak of hives， swelling of the face， eyes， or throat， chest pain， nausea， severe sweating， and even difficulties breathing or speaking.
　　According to Lu Yongyue’s estimates， there are hundreds of thousands of people stung by the RIFA every year in China and tens of thousands may display serious symptoms.
　　“Since first being spotted， the RIFA has been spreading swiftly across China，” Feng Xiaodong， an official with the National Agricultural Technology Promotion and Service Center， said.
　　He said that in 2005， the pest affected over 40 county-level divisions， and this number had increased to 281 by December 2016.
　　According to MARA， the insect has spread to over 400 county level divisions at present.

Solutions

　　Lu Yongyue’s center has carried out research on the spread and outbreak patterns of the ant， its effect on the nation’s ecosystem as well as methods of prevention and control over the past decade.
　　However， its control faces some difficulties. Lu Yongyue said that given the ant is widespread in the country， researchers can’t study all of them. Also， although researchers have developed effective pesticides， their efficacy has been compromised by the relevant factories’ poor production techniques.
　　Compared with conventional pesticides， Lu Lihua said the usage of poisonous bait is a more ideal way of killing the pest. He said that by spraying 20 grams of bait along the path near the mound that the RIFA passes by to fetch food， a whole nest of ants can be killed in seven to 10 days.
　　This is because， as a social insect， the RIFA exchanges food to pass on information. If one ant takes the bait， the poison will spread throughout the nest.
　　Researchers have been trying to curb the insect by finding its weak points. Lu Lihua said the RIFA is at its weakest right after mating. Winged RIFAs can fly into the air to mate and after mating， the male ant dies and the female ant lands on the ground to build a nest and produce the eggs to become an ant queen.
　　The ant queen is at her most vulnerable when she lands on the ground after mating where she might then be eaten by indigenous ants， beetles or spiders.
　　Lu Lihua suggested gene editing may provide a solution to the RIFA outbreak. If the gene that causes the female RIFA to grow wings can be changed， this will bring the species under effective control. BR