Fire ant

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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 (genus Solenopsis) are a variety of stinging ants with over 285 species worldwide. They have several other common names, including ginger ants, tropical fire ants, and red ants.

Contents

Appearance [edit]

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 be present in the same nest.

Solenopsis spp. ants can be identified by 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 formicine ants can cause irritation by spraying formic acid; myrmecine ants like fire ants have a dedicated venom-injecting sting which injects an alkaloid venom as well as mandibles.

Behavior [edit]

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 people. The liquid 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]

Roles [edit]

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

Queen [edit]

A queen is generally the largest individual in the colony. Her primary function is reproduction; she may live for 6 to 7 years and can produce up to 3,500 eggs in a single day. That is roughly 9 million in her lifetime. She is usually the most important ant in the colony, and is usually the biggest ant in the colony. Young, virgin queens have wings (as do males), but they rip them off after mating.

Males (drones) [edit]

Males mate with the queen. They die immediately after mating.

There are other types of roles in an ant colony like the workers and the soldier ants. The soldier ants are known for their larger and more powerful mandibles while the worker takes care of regular tasks (the main tasks in a colony are caring for the eggs/larvae/pupae, cleaning the nest, and foraging for food).

Invasive species [edit]

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

Although most fire ant species do not bother people and are not invasive, 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 that 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 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, except for 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.[citation needed]

In just seventy years, according to a study published in 2009, lizards in parts of the United States have adapted to have longer legs and new behaviors that aid them in escaping fire ants.[6]

Symptoms and treatment [edit]

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). Some people are allergic to the venom, and as with many allergies, may experience anaphylaxis, which requires emergency treatment. Other problems are concentrated to the site of the sting.

The sting swells into a bump, which can cause much pain and irritation, especially when several stings are 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.[7] First aid for fire ant bites includes external treatments and oral medicines. There are also many home remedies of varying efficacy, including urine immediate applied or aloe vera gel, the latter of which is also often included in over-the-counter creams that also include medically tested and verified treatments.

External, topical treatments include the surface anesthetic benzocaine, the antihistamine benadryl, and the corticosteroid hydrocortisone.[8] Antihistamines or topical corticosteroids may help reduce the itching[citation needed].

Oral medicines include antihistamines.[citation needed]

This list is incomplete; you can help by expanding it.

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.

Predators [edit]

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" (that look like teeth) within 30 seconds, the leaf closes around the prey and digests it.

Species [edit]

This species list is complete.[citation needed]

See also [edit]

Footnotes [edit]

  1. ^ "Colonies in Florida dissected and observed with greater than five queens". BioOne. 1970-01-01. 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. 
  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, Professor and Extension Entomologist (2002-12). "Medical Problems And Treatment Considerations For The Red Imported Fire Ant". Texas A&M University. p. 4. Retrieved 2012-12-11. 
  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 [edit]

External links [edit]

Wikimedia Commons has media related to: Solenopsis
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