Solenopsis invicta
Solenopsis invicta, commonly known as the Red Imported Fire Ant (RIFA) or simply fire ant, is one of 266 species of ant in the genus Solenopsis. Solenopsis invicta belongs to the animalia kingdom, arthropoda phylum, insecta class, hymenoptera order, and formicidae family. They are originated from South America, and it is believed that they were accidentally introduced into the United States in the 1930s, having hitched a ride on a ship to Mobile, Alabama.
| Solenopsis invicta | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
  | ||||||||||||||
| Solenopsis invicta | ||||||||||||||
| Scientific classification | ||||||||||||||
| ||||||||||||||
| Binomial nomenclature | ||||||||||||||
| Solenopsis invicta |
They are more aggressive than most native species of ants and their sting is quite painful. A person typically encounters them by accidentally stepping into one of their mounds, which causes the ants to swarm up the person's legs, attacking en masse.
Fire ants are efficient competitors to other ants, and have been successful at enlarging their range in the U.S., gradually spreading north and west despite intense efforts to stop them. Today they are found in most of the southern states, including Texas. It is not uncommon for several fire ant mounds to appear suddenly in a suburban yard or a farmer's field, seemingly overnight.
(At least one community uses the presence of fire ants as a publicity opportunity: Marshall, Texas, hosts an annual fire ant festival.)
Fire ants are still on the move, too, often traveling from one area to another in turf, root balls of nursery plants, and other agricultural products. They are a pest not only because of the physical pain they can inflict, but also because their mound-building acitivity can damage plant roots and lead to loss of crops. Although their stings are rarely life-threatening to humans and other large animals, they can kill smaller animals such as birds.
At present fire ants in the US can be controlled but not eradicated. A number of products are available which can be used on a mound-by-mound basis to destroy the ants' colonies when they appear. With all such efforts, it is important to reach and kill the queen (or queens), which may be as deep as six feet underground; otherwise she may simply move a short distance away and quickly establish a new colony.
An outbreak of the ants in Queensland, Australia, occurred in 2001. It is believed the ants were present in shipping containers. Only after sustained government inaction became a major public issue did substantial control measures begin to be put into place. A five year AU$145m eradication programme has begun involving the employment of 500 controllers and the baiting of 100,000 homes. The first of 12 chemical treatment rounds in the Brisbane area was 80 per cent successful according to Queensland Primary Industries Minister Henry Palaszczuk.
| Table of contents |
|
2 Life cycle 3 Spread 4 Countermeasures 5 See also 6 External link |
Fire ants are symmetrical along the body, meaning that the left part is the mirror image to the right. The ants have hardened exoskeleton, meaning that they have no bones or internal supporting tissues, but tough integuments for support and protection. The fire ants breathe through their tracheas.
Their bodies can be classified into three major parts: head, chest and abdomen. They have three pairs of legs, and a pair of antennae attaching to the head. (personal interview) Just like other ants, the worker and soldiers ants are female. The queen is responsible for laying thousands of eggs. The number of males is low, because only one male is needed for the entire reproduction.
Unlike most peopleÃÂÃÂs perception that fire ants bite and inject venoms, they actually have stings like most wasps and bees do. The stings are located at the end of their abdomens. When the fire ants sting, they use their strong mandibles to attach themselves to the victimÃÂÃÂs flesh, and then they can sting for many times continuously.
The life cycle starts with the queen mates with a male. After mating, the male dies, and the female begins to lay eggs. During the process, the queen has to survive on her previously deposited food and her shed wings as energy source. The queen would first lay about ten eggs that would also take ten days to hatch. It will be approximately twenty more days before the larvae become worker ants. As a result, the first worker ants are very small in size. Gradually, the size and the number of worker increase as the queen is fed with more nutrients.
Since the 1940's, after their initial arrival, they have increased exponentially in numbers, doing more harm than good. They build mounds, no larger than 46 cm. in diameter and 18 inches in height, on soil close to homes and other buildings, sometimes forage indoors for food and moisture. They are a nuisance and can threaten sleeping or bed-ridden individuals and pets. Occasionally, they feed on vegetable plants in home gardens. The worst damage usually occurs during hot, dry weather; they invade flowerbeds seeking warmth and moisture. If disturbed, they bite and sting the intruder. The sting of the RIFA has venom composed of a necrotizing alkaloid which causes both pain and white pustules that appear one day after the sting.
These ants have received more attention because of the damage they have caused to farmers, buildings, and even physical damage to animals including humans. They are extremely aggressive and has the ability to deliver venom in unison.
They are attracted to electrical fields and crawl into air conditioning units and the wiring of stop-lights until they short them out. This is the leadiung cause of traffic light shorts in Texas. It should be noted that they are excellent natural predators, biological controls, for pests such as the sugarcane borer, the rice stink bug, the striped earwig, aphids, the boll weevil, the sybean looper, the cotton leafworm, the hornfly, and many other pests harmful to crops. Seeds, fruits, leaves, roots, bark, nectar, sap, fungi, and carrion are all on their menu, they are not shy about creating their own carrion either. They are proficient enough at overwhelming intruders that they can pretty much clear an area of invertebrates, lizards and ground-dwelling birds.
The red fire ants are foreign, they have virtually no natural enemies in the States or in Australia. Fortunately, many scientists and agencies are developing prolific methods to stop the spread of fire ants.
The prevention of plague has been through pesticide use, but current research is introducing natural enemies of the red imported fire ant -- microsporidian protozoan Thelohania solenopsae and the fungus Beauveria bassiana are promising pathogens. Pseudacteon tricuspis and Pseudacteon curvatus, parasitoid flies from South America, decapitate worker ants in the final stages of larval development. Solenopsis daguerri (Santschi), a parasitic ant, invades RIFA colonies to replace the queen in hopes of gaining control of the colony. For this reason, it is also being probed as a biological control agent.
Some exciting work is being done in the area of biological controls. One promising avenue involves introducing, into infested areas, a species of phorid fly found in the ants' native habitat that parasitizes the ants. A fascinating description of the parasitization mechanism may be found at this external site: [1] Large-scale use of such controls is for the future, though, and it remains to be seen how successful it will be.Body structure
Life cycle
Spread
Countermeasures