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 souththeast Asia, please see Oecophylla smaragdina. For the little fire ant, Wasmannia auropunctata, see Electric ant. For the European fire ant see Myrmica rubra.
"Red Ant" redirects here. For the Australian video and software distributor, see Red Ant Enterprises.
Fire ant
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
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 285 species worldwide. They have several common names, including ginger ants, tropical fire ants and red ants.

Contents

[edit] Appearance

Fire ant mound

The bodies of fire ants, like all insects' bodies, are divided 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 2 mm to 6 mm (0.12 in to 0.24 in). These different sizes of the ants can all exist in the same nest.

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

Many ants bite, and can cause irritation by injecting formic acid; stinging ants have a dedicated venom-injecting sting as well as mandibles.

[edit] Behavior

A fire ant worker, queen, and male (clockwise from bottom left)

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.

Fire ants nest in the soil, often near moist areas, such as river banks, pond shores, watered lawns and highway shoulder. Usually, the nest will not be visible, as it will be built under objects such as timber, logs, rocks, or bricks. If there is no cover for nesting, dome-shaped mounds will be constructed, but these are usually only found in open spaces, such as fields, parks and lawns. These mounds can reach heights of 40 cm (15.7 in), and can also be as deep as a metre and a half (five feet).[1] 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]

[edit] Roles

Solenopsis queens and workers
Forelius ants with a dead Romalea guttata grasshopper

[edit] Queen

A queen is generally the largest individual in the colony. Her primary function is reproduction; she may live for six to seven years and produce up to 3,500 eggs per day.

[edit] Males (drones)

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

[edit] Workers

The workers are sterile females which 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. Life span 1 month.

[edit] Introduced species

For more details on invasive subspecies, see Red imported fire ant.

Although most fire ant species do not bother people and are not invasive due to biological factors, Solenopsis invicta, known in the United States 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, and came to infest the majority of the Southern and Southwestern United States.[2]

In the US the FDA estimates more than US$5 billion is spent annually on medical treatment, damage, and control in RIFA-infested areas. Furthermore, the ants cause approximately $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 programs to control or eradicate the species, but, other than Australia, none have been especially effective. In Australia, an intensive program costing A$175 million had by February 2007 eradicated 99% of fire ants from the sole infestation occurring in south-east Queensland.

In just seventy years, according to a study published in 2009, lizards in parts of the United States had developed longer legs and new behaviors to escape the ants, which can kill the lizard in under a minute.[6]

[edit] Symptoms and treatment

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

The venom of fire ants is composed of alkaloids such as piperidine (see Solenopsis saevissima). The sting swells into a bump, which can cause much pain and irritation at times, especially when caused by several stings in the same place. The bump often forms into a white pustule, which can become infected if scratched, but if left alone will usually flatten within a few days. The pustules are obtrusive and uncomfortable while active and, if they become infected, can cause scarring. 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[citation needed].

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

Severe allergic reactions to fire ant stings, including severe chest pain, nausea, severe sweating, loss of breath, serious swelling, and slurred speech,[9] can be fatal if not treated.

[edit] 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, emerging two weeks later.[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.

The Venus Flytrap, a carnivorous plant, is native to the North and South Carolina of the United States. The diet of the Venus Flytrap includes 33% ants, of any species. They lure their prey to their trap by using a sweet sap. Once the prey has fallen into the trap and touched three "hairs" within 30 seconds, the leaf closes around the prey and digests it.

[edit] Species

This species list is complete.

[edit] See also

[edit] Footnotes

  1. ^ "Colonies in Florida dissected and observed with greater than five queens". Bioone.org. 1970-01-01. http://www.bioone.org/perlserv/?request=get-document&issn=0015-4040&volume=086&issue=03&page=0381. Retrieved 2010-06-28. 
  2. ^ "Imported Fire Ants". University of Minnesota.
  3. ^ McDonald, Maggie (February 2006). "Reds Under Your Feet (interview with Robert Vander Meer)". New Scientist 189 (2538): 50. http://www.newscientist.com/channel/opinion/mg18925381.700-interview-extinguishing-red-fire-ants.html. 
  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. doi:10.1056/NEJM199008163230707. PMID 2197555. 
  8. ^ Bastiaan M. Drees (2002-12). "Medical Problems And Treatment Considerations For The Red Imported Fire Ant". Texas A&M University. p. 4. http://fireant.tamu.edu/materials/factsheets_pubs/pdf/FAPFS023_2002rev_Medical.pdf. Retrieved 2009-09-09. 
  9. ^ "Insects and Scorpions". The National Institute for Occupational Safety and Health. 2008-10-22. http://www.cdc.gov/niosh/topics/insects/. Retrieved 2008-11-04. 
  10. ^ Rachel Ehrenberg. "Ant Venom Attracts Decapitating Flies", Science News, September 20, 2009

[edit] References

[edit] External links

Wikimedia Commons has media related to: Solenopsis
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