Fire Ants Form Rafts To Survive Floods

Why, if a fire ant alone in water drowns, while it can survive and float for days when in a group? Researchers at the Georgia Institute of Technology, USA, have found that fire ants (Solenopsis invicta) create a kind of raft water resistant when floods to save the colony.

This is a tortilla-shaped structure, and almost half of the colony is submerged to keep afloat the rest, as explained in an article published today in the journal Proceedings of the National Academy of Science (PNAS).

To see how these highly invasive insects react to an emergency working together, the team led by David Hu threw between 500and 8000 ants to water. They noted that quickly gathered, clutching each other with their jaws and claws to form the structure.

According to the authors, the formation of air trapped under the rafts are likely to increase buoyancy and prevent the ants from the bottom layer from drowning. Gradually removing the ants from the top than the bottom found moved to keep the average thickness of the reservoir. According to the researchers, this cooperative behavior among ants could be based on coercion.

The red imported fire ant is one of over 280 species in the widespread genus Solenopsis. Although the red imported fire ant is native to South America, it has become a pest in the southern United States, Australia, Taiwan, Philippines, and the southern Chinese province of Guangdong.

There are also reports of ant hills in Macau, the former Portuguese enclave that borders the province of Guangdong. RIFA are known to have a strong, painful, and persistent irritating sting that often leaves a pustule on the skin.

The Solenopsis invicta are found colonizing in many area of Costa Rica. The red imported fire ant are more aggressive than most native ant species and have a painful sting.

A person typically encounters them by inadvertently stepping into one of their mounds, which causes the ants to swarm up the person's legs, attacking en masse. The ants respond to pheromones that are released by the first ant to attack. The ants then sting in concert, often inflicting death on smaller animals by overloading their immune systems

The red imported fire ant compete successfully against other ants.

Red imported fire ants have both a pedicel and postpediole. In other words, they belong to a group of ants that have two humps between the thorax and abdomen. The workers have ten antennal segments terminating in a two-segmented club. It is often difficult to distinguish between the red imported fire ant Solenopsis invicta and some other species in the genus. A number of characters are used, but are not always consistent between the black imported fire ant (Solenopsis richteri) or hybrids between the two species. Positive identifications can be made using high performance liquid chromatography (HPLC) to distinguish differences in the cuticular hydrocarbons.

Many scientists and agencies are attempting to develop methods to stop the spread of the red imported fire ant. Traditionally, control of the red imported fire ant has been achieved through pesticide use. Red imported fire ants have virtually no natural biological control agents in the United States, China, Philippines, or Australia. Current research is focused on introducing biological control agents from the red imported fire ant's native range.