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Fire ant

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This page is about stinging ants in the genus Solenopsis. For the aggressive red weaver ants sometimes called "fire ants" in Southeast Asia please see Oecophylla smaragdina. For the Little Fire Ant, Wasmannia auropunctata, see Electric ant.
"Red Ant" redirects here. For the Australian video and software distributor, see Red Ant Enterprises.

Fire ant
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Subphylum:
Uniramia
Class:
Insecta
Order:
Hymenoptera
Suborder:
Apocrita
Family:
Formicidae
Subfamily:
Myrmicinae
Tribe:
Solenopsidini
Genus:
Solenopsis

Westwood, 1840
Species

S. conjurata
S. daguerrei
S. fugax
S. invicta
S. molesta
S. richteri
S. solenopsidis
S. wagneri
S. xyloni
 many more, see text

Fire ants are a variety of stinging ants with over 280 species worldwide. They have several common names including ginger ants and tropical fire ants (English), hormigas bravas or hormigas coloradas (Spanish), fourmis de feu (French), Feuerameisen (German), mod-kun-fai (Thai), aka-hi-ari or aka-kami-ari (Japanese), and Langgam (Filipino).

Appearance

S. conjurata worker
Fire Ant Mound

The bodies of fire ants, like all insects' bodies, are broken up into three sections: the head, the thorax, and the abdomen, with three pairs of legs and a pair of antennae. Fire ants can be distinguished from other ants by their copper brown head and body with a darker abdomen. The worker ants are blackish to reddish, and their size varies from 2mm to 6 mm (0.12 in to 0.24 in). These different sizes of the ants can all exist in the same nest.

Solenopsis sp. ants can be identified with three body features — a pedicel with two nodes, an unarmed propodium, and antennae with 10 segments and a two segmented club.

Behavior

A typical fire ant colony produces large mounds in open areas, and feeds mostly on young plants, seeds, and sometimes crickets. Fire ants often attack small animals and can kill them. Unlike many other ants, which bite and then spray acid on the wound, fire ants bite only to get a grip and then sting (from the abdomen) and inject a toxic alkaloid venom called solenopsin, a compound from the class of piperidines. For humans, this is a painful sting, a sensation similar to what one feels when burned by fire—hence the name fire ant—and the after effects of the sting can be deadly to sensitive individuals. The venom is both insecticidal and antibiotic. Researchers have proposed that ant nurse workers will spray their brood to protect them from microorganisms.

Fire ants nest in the soil, often near moist areas, such as river banks, pond edges, watered lawns and highway edges. Usually the nest will not be visible as it will be built under objects such as timber, logs, rocks, pavers, bricks, etc. If there is no cover for nesting, dome-shaped mounds will be constructed, but this is usually only found in open spaces such as fields, parks and lawns. These mounds can reach heights of 40 cm (15.7 in). The mounds that the fire ants live in can also be as deep as five feet.

Colonies are founded by small groups of queens or single queens. Even if only one queen survives, within a month or so the colony can expand to thousands of individuals. Some colonies may be polygynous (having multiple queens per nest).[1]

Roles

Solenopsis queens and workers
Fire ants on a dead grasshopper

Queen

A queen is generally the largest individual in the colony. The primary function of the queen is reproduction; she may live for 6 to 7 years and produce up to 1,500 eggs per day. Many fire ant colonies will have more than one queen.

An established nest can have up to 8 inactive sub-queens that will flee the nest if threatened, which is why poisoning a nest may not completely rid a property of the ants.

Males / Drones

Males mate with the queen for the sole purpose of producing offspring. Their lifespan is approximately three days.

Workers

The workers are sterile females who build and repair the nest, care for the young, defend the nest, and feed both young and adult ants. The worker ants also go find supplies to build up the colony.

Introduced species

Further information: Red imported fire ant and invasive subspecies

Although most fire ant species do not bother people and are not invasive due to biological factors, Solenopsis invicta, commonly known as the red imported fire ant (or RIFA) is an invasive pest in many areas of the world, notably the United States, Australia, the Philippines, China and Taiwan. The RIFA was accidentally introduced into the United States aboard a South American cargo ship that docked at the port of Mobile, Alabama, in the 1930s, but now infests the majority of the Southern and Southwestern United States.[2]

In the US, the FDA estimates that more than US$5 billion is spent annually on medical treatment, damage, and control in RIFA-infested areas. Furthermore, the ants cause approximately US$750 million in damage annually to agricultural assets, including veterinarian bills and livestock loss as well as crop loss.[3] Over 40 million people live in RIFA-infested areas in the southeastern United States.[4] Between 30 and 60% of the people living in fire ant-infested areas are stung each year.[5] Since September 2004, Taiwan has been seriously affected by the red fire ant. The US, Taiwan and Australia all have ongoing national efforts to control or eradicate the species, but, other than Australia, none have been especially effective. In Australia an intensive program costing A$175 million has, at February 2007, eradicated 99% of fire ants from the sole infestation occurring in South East Queensland.

In just 70 years, according to a new study, lizards in parts of the United States have developed longer legs and new behaviors to escape the ants, which can kill the lizard in under a minute.[6]

Symptoms and first aid

A human leg three days after coming in brief contact with a fire ant colony

The venom of the fire ants is composed of alkaloids such as piperidine (see Solenopsis saevissima), and the sting swells into a bump. This can cause much pain and irritation at times, especially when stung repeatedly by several at once. The bump often forms into a white pustule, which is at risk of becoming infected if scratched; however, if left alone, it will usually go down within a few days. The pustules are obtrusive and uncomfortable while active and, if the sting sites become infected, can turn into scars. Additionally, some people are allergic to the venom and, as with many allergies, may experience anaphylaxis, which requires emergency treatment.[7] An antihistamine or topical corticosteroids may help reduce the itching.

First aid for fire ant bites includes external treatments and oral medicines.

Victims who experience severe or life threatening allergic reactions to fire ant insect stings should visit a doctor or hospital immediately upon contact as these reactions can result in death. These more severe reactions include severe chest pain, nausea, severe sweating, loss of breath, serious swelling, or slurred speech.[9]

Other names

In Spanish, fire ants are known as hormiga colorada/roja (red ant) or hormiga brava (fierce ant). In the Dominican Republic they are known as Hormiga Caribe. In Portuguese, they are called formiga de fogo (fire ant) and formiga lava-pé (wash foot ant).

Natural predators

Phorid flies, or Phoridae, are a family of small, hump-backed flies resembling fruit flies; two species in this family (Pseudacteon tricuspis and Pseudacteon curvatus) are parasitoids of the red imported fire ant in its native range in South America. Some 110 species of the genus Pseudacteon, or ant-decapitating flies, have been described. Members of Pseudacteon reproduce by laying eggs in the thorax of the ant. The first instar larvae migrates to the head, then develops by feeding on the hemolymph, muscle tissue, and nervous tissue. After about two weeks, they cause the ant's head to fall off by releasing an enzyme that dissolves the membrane attaching the ant's head to its body. The fly pupates in the detached head capsule, requiring a further two weeks before emerging.[10]

Pseudacteon flies have been widely introduced throughout the southern United States, starting with Travis, Brazos, and Dallas counties in Texas, as well as Mobile, Alabama, where the ants first entered North America.

Species

This species list is complete.

See also

Footnotes

  1. ^ "Colonies in Florida dissected and observed with greater than five queens". Bioone.org. 1970-01-01. Retrieved 2010-06-28.
  2. ^ "Imported Fire Ants". University of Minnesota.
  3. ^ McDonald, Maggie (2006). "Reds Under Your Feet (interview with Robert Vander Meer)". New Scientist. 189 (2538): 50. {{cite journal}}: Unknown parameter |month= ignored (help)
  4. ^ "Anaphylaxis due to Red Imported Fire Ant sting". The Medical Journal of Australia 2002.
  5. ^ "Public health significance of Urban Pests". World Health Organization Technical Report.Pharaoh ants and fire ants.p.175-208. June 25, 2008.
  6. ^ "Lizards' Dance Avoids Deadly Ants". LiveScience. January 26, 2009.
  7. ^ deShazo RD, Butcher BT, Banks WA (1990). "Reactions to the stings of the imported fire ant". N. Engl. J. Med. 323 (7): 462–6. PMID 2197555.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. ^ Bastiaan M. Drees (2002-12). "Medical Problems And Treatment Considerations For The Red Imported Fire Ant" (PDF). Texas A&M University. p. 4. Retrieved 2009-09-09. {{cite web}}: Check date values in: |date= (help); Cite has empty unknown parameter: |coauthors= (help)
  9. ^ "Insects and Scorpions". The National Institute for Occupational Safety and Health. 2008-10-22. Retrieved 2008-11-04.
  10. ^ Rachel Ehrenberg. "Ant Venom Attracts Decapitating Flies", Science News, September 20, 2009

References

Wikimedia Commons has media related to Solenopsis.
Wikispecies has information related to Solenopsis.
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