Fire ants have been in the United States for over sixty years, and almost every American that lives in or frequently visits the quarantined states which they inhabit has had an unpleasant run in with these troublesome critters. Inhabitants of the Southeast who have ever stood unwittingly atop a fire ant mound know that the insects are aptly named. When the ants sting it creates a sensation similar to scorching caused by a hot needle touching the skin momentarily (1. Tschinkel 474). Fire ants are native to South America and were introduced to the United States in 1928 through a port in Mobile, Alabama. The ants were stowaways hidden in soil used for ballast and in dunnage dropped off the ships once they had sailed from South America to the ports of Alabama (2. Lockley 31). The two basic species of fire ants in the United States are the are black and red, they vary in length from one eighth to one quarter inch. Black fire ants arrived first followed shortly by the infamous imported red fire ants. Black ants (Solenopsis Richteri Forel) were the first to arrive and spread slowly but steadily despite government intervention to stop them from spreading(3. Lockley 33). These black ants would spread much further then the second wave of imported ants recognized as Solenopsis Invicta Buren or red fire ants(4. Lockley 33). This second wave of ants arrived in about 1945 and spread much more rapidly and dominated the previous more passive black ant(5. Lockley 34). Homer Collins, a fire an t expert, stated that “The new invader, known as the red imported fire ant, proved more adaptive and rapidly displaced the existing imported black ant. By 1949, Solenopsis Invicta Buren were the dominant species of imported fire ant. Ants could be found in commercial ornamental-plant nurseries in the heart of the Southeast.” Red ants are a particularly aggressive ant species that, like the killer bees, are rapidly spreading northward from the Southeastern United States, and have traveled as far west as Texas and as far north as North Carolina. “Experts predict that the ants may eventually reach as far west as California and as far north as Chesapeake Bay.”(7. Tschinkel 474). The spread of fire ants into new areas depends on many factors: the existing level of fire ant population, climate, competition, and natural predators . In areas where other ant populations are well established and an abundance of natural enemies exist, colony establishment is hindered because of the threat to the queen and the competition for resources. Man and his need for cleared land has created open sunny areas free of natural enemies and fewer competitors and inadvertently aided the spread of the fire ants(8. Lockley 35). Fire ant infestation is a very serious problem in the Southern United States ranging from Florida, West along the Gulf Coast region, to West Texas. Over 200,000,000 acres of land in the United States and Puerto Rico are infested with fire ants. They pose a major economic threat to the agricultural and ranching industries, lawns, gardens and recreational areas, as well as a threat to animal life and even human life. The total cost of controlling the ants, preventing the damage, and treating the medical problems in urban and rural areas is estimated to be $2.7 billion per year (9. Lockley 36). When native species are defeated by aggressive invaders, the cost is measured in lost species and disrupted communities. The result, predicted ecologist Gordon Orians at the 1994 Ecological Society of America Conference, will be the “Homogocene,” an era in which the world’s biota is homogenized through biological invasions (10. Lockley 37). Fire ants use their stingers to immobilize or kill prey and to defend ant mounds from disturbance by larger animals such as humans. Any disturbance sends hundreds of workers out to attack the potential nourishment or predator. The ant grabs its victim with its mandibles (mouth parts) and then inserts its stinger. The process of stinging releases a chemical which alerts other ants, inducing them to sting simultaneously. In addition, one ant can sting several times, even after its’ venom sack has been emptied, without letting go with its mandibles(11. Lockley 37). Once stung, human beings experience a sharp pain which lasts a couple of minutes. These ants are notorious for their painful, burning sting that results in a pustule and intense itching, which may persist for ten days. Initially the sting results in a localized intense burning sensation (hence the name “fire” ant).
This is followed within 14-18 hours by the formation of a white pustule at the sting site. These pustules can become sites of secondary infection if the pustules are broken or are not kept clean, in some cases they can leave permanent scarring(12 Lockley 38). Some people have allergic reactions to fire ant stings that range from rashes and swelling to paralysis, or anaphylactic shock. In rare instances, severe allergic reactions can cause death(14. Lockley 35). Then the sting starts itching and a welt appears. Fire ant venom contains alkaloids and a relatively small amount of protein compared to other stinging insects. The alkaloids in the venom kill skin cells; this attracts white blood cells, which form a pustule within a few hours of being stung. The fluid in the pustule is sterile, but if the pustule is broken the wound may become infected. The protein in the venom can cause allergic reactions including nausea, vomiting, dizziness, perspiration, cyanosis, and asthma which may require medical attention. Death has been known to result when toddlers fall on fire ant mounds and when adults have extreme allergic reactions. Although fire ant stings are not as painful as those of harvester ants or as dangerous as those of bees and wasps, their greater numbers raise them to the status of pest. Although less than one percent of the population requires medical attention after a sting, so many people live in areas infested with fire ants and fire ants are so dense i n these areas that this translates to tens of thousands of people requiring medical attention for fire ant bites each year. Fire Ants construct nests which are often in the form of dome-shaped mounds of soil, sometimes as large as three feet across and one and one half feet in height. In sandy soils, mounds are flatter and less visible(15. Lockley 38).. Fire ants usually build mounds in sunny, open areas such as lawns, pastures, cultivated fields, and meadows, but they are not restricted to these areas. Mounds or nests may be located in rotting logs, dried cow manure, around trees and stumps, under pavement and buildings, and occasionally indoor. When the nest is disturbed, numerous fire ants will quickly disperse out of the mound and attack any intruder. The mound serves three primary purposes: it is a platform for nuptial flights, a place to raise the colony above the water table in soaked soil, and it collects the suns warmth during the cold months of winter(16. Melnick 14). Fire Ant colonies consist of eggs, brood, minim and major workers, and one or more reproductive queens. A colony is usually started by a single queen, however some beginning colonies can have up to five queens(17. Lockley 39).
Mature colonies often posses more than one queen. During the spring and summer, winged males and females leave the mound and mate in the air. After mating females become queens and may fly up to ten miles from the parent colony. However, most queens descend to the ground within much shorter distances. Only a small percentage of queens survive after landing. Most queens are killed by foraging ants, especially other fire ants. If a queen survives she sheds her wings, burrows into the ground, and lays eggs to begin a new colony. A queen ant lays her eggs in a brood chamber twenty five to fifty millimeters deep in the mound. After twenty to thirty days the first workers appear(18. Melnick 14). These workers, called minims, are very small due to the limited amount of energy and resources the queen can devote to them. The minims explore the outside world and forage for food to feed the queen and the developing colony. Within thirty days the next wave of workers emerge and are up to ten times larger than the minims(19. Lockley 39). These workers are called majors and perform the tasks of expanding the mound and foraging for nourishment. The labor is divided by age, and to a lesser degree by size. Youngest and smallest workers are given the job of caring for the developing eggs and brood. Middle-aged workers are tasked with colony maintenance while the eldest and largest workers forage for food and defend the mound. A colony may contain as many as 240,000 workers after three years(20. Lockley 39). Fire ants are omnivorous, feeding on almost any plant or animal material; although insects seem to be their preferred food. The arrival of imported fire ants into an ecosystem can wreak havoc on the local ecological community. Studies have shown that a minimum two-fold reduction occurs among populations of field mice, snakes, turtles and other vertebrates when fire ants are allowed to establish colonies within a given area. In some instances, the depredation by fire ants has completely eliminated spiders, scorpions, mites, centipedes, ground nesting mammals and birds from an ecosystem(21. Lockley 41). Fire ants are not only a threat to other insects and small mammals, they also cause billion dollars worth of damage per year. In Urban areas ants are attracted to electrical currents and cause considerable damage to heat pumps, air conditioners, telephone junction boxes, transformers, traffic lights, gasoline pumps, et cetra (22. Lockley 41). In agriculture, fire ants have been identified as damaging corn, soybeans, citrus trees, okra, and up to fifty-four other different species of cultivated plants. Ants are also known for feeding upon arthropod predators and other beneficial insects, eating upon ground nesting vertebrates and other wildlife, damage to asphalt roads, damage of farm equipment and machinery(23. Lockley 41). It is very difficult to find an effective method to exterminate fire ant colonies. Four basic methods used to aid in the extermination of fire ants are: individual mound treatment, broadcast treatments, biological control, and the effects of natural enemies. Individual mound treatments are simply applying a insecticide directly on the mound and allowing the worker ants to carry the poison into the colony and feed it to the brood and queen. Broadcast treatment do not require the locating of each mound but still rely on the worker ants to bring the insecticide back to the mound to kill the queen and young. Biological and natural enemies feed upon the ants themselves, like parasites, to terminate the colony.
Prevention is the key to reducing the threat of fire ant infestations indoors, which means removing exposed food sources that may attract these insects. If fire ants enter a building, the treatment objective must be to reduce the potential for accidental stings as quickly as possible. Insecticides labeled for indoor use particularly pyrethroids, can be used in homes and public buildings to drive foraging ants outside or away from critical areas, such as kitchens, recreation rooms, patient rooms, operating rooms, or intensive care units. Baits work well for many ants that invade buildings. However the baits should be used in moderation to control fire ants indoors because they are likely to attract additional foraging ants, increasing the chance that an occupant will be stung. Ultimately, long-term control of fire ants indoors can be achieved only by locating and treating their mound or mounds, probably with an insecticide drench(24. Lockley 42) Fire ants both black and red have caused billion dollars in damage since their introduction to the United States over sixty years ago. Even in 1997 society has not found an effective way to exterminate or control the spread of these troublesome insects. As mankind chooses to genetically experiment with species and continues to connect the remote areas of the world with faster and more efficient means of moving food and goods. Occurrences of accidental transportation of troublesome pests, bacteria, and viruses will also increase. The fire ant while costly and annoying won’t cause the absolute destruction of life as we know it. Fire ants are however a reminder that ecosystems are a delicately balanced environments with forces that keep the food chain functioning. The fire ant and the African killer bee do not have natural enemies in the Southern United States that reside in South Africa. As mankind destroys the rain forests of South America for cattle grazing, he has released things like the Hunta virus, and the Ebola virus in Africa. Both of these viruses could rapidly destroy populations. Mankind has made tremendous leaps in knowledge and technology during this century. If this use of that technology is not metered and controlled intelligently it may be the downfall of the mankind.
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