Invasion history and dispersal routes

Two fire ant species (IFA: imported fire ant) originating from South America had invaded the southern US at the beginning of the 20th century. The black imported fire ant (BIFA, Solenopsis richteri) and red imported fire ant (RIFA, S. invicta) sequentially invaded the southeastern US from Mobile , Alabama which was the initial point of introduction in 1918 and 1930, respectively. Consequently, they have caused serious damage for almost a century. They were presumed to have been introduced by the transportation of cargo and containers.

After introduction into the US , fire ants expanded their territory at a rate of 198 km /year, and 10 states had subsequently been occupied by fire ants by 1953. Furthermore, the construction of freeways accelerated the dispersal and expansion of the fire ant and allowed it to reach southern California by 1998 by passing through the desert where they are theoretically unable to survive. In total, 12 states are reported as being infested with fire ants: Alabama , Arkansas , California , Florida , Georgia , Louisiana , Mississippi , North Carolina , Oklahoma , South Carolina , Tennessee , and Texas . In addition, Puerto Rico was found to have been invaded during 1975~1984.

Although all countries have focused on preventing invasion, fire ants still successfully strode across the Pacific Ocean and established their population in Australia with the increase in global trade. The Australian government has estimated that fire ants may cause more than AUS$10 billion in economic losses if the government fails to eradicate them. In addition, the government conducted a 6-year eradication program for fire ants, including control, prevention, and eradication, with an expected cost of about AUS$200 million.

  1. Nursery stocks and plantations with fire ant-infested soil.

2. Imported culture soil infested with fire ants.

3. Reproductive colonies carried in transportation containers.

 

Post-invasion dispersal routes in Taiwan

1. Active dispersal (natural way): nuptial flight, flooding.

2. Passive dispersal: infested nursery stock or turf, movement of soils and fertilizers, agricultural equipment, infested containers, and infested vehicles.

 

Type of infested areas

1. Agricultural environment: rice fields, vegetable farms, floriculture gardens, horticulture gardens, fallow lands, farmhouses, bamboo groves, and others.

2. Urban environment: parks, shade trees, school fields, grassy areas, railways, open areas, and electrical facilities.