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The red imported fire ant (''Solenopsis invicta''), also known as the fire ant or RIFA, is a species of ant native to South America. A member of the genus '' Solenopsis'' in the subfamily
The red imported fire ant was first described by Swiss entomologist Felix Santschi in a 1916 journal article published by ''Physis''. Originally named ''Solenopsis saevissima wagneri'' from a syntype worker collected from 
In a 1991 review of the species complex, American entomologist James Trager synonymised ''S. saevissima electra wagneri'' and ''S. wagneri'' together. Trager incorrectly cites ''Solenopsis saevissima electra wagneri'' as the original name, erroneously believing that the name ''S. wagneri'' was unavailable and used Buren's name ''S. invicta''. Trager previously believed that ''S. invicta'' was conspecific with ''S. saevissima'' until comparing the material with ''S. wagneri''. Trager notes that though ''S. wagneri'' has priority over ''S. invicta'', the name was never used above infrasubspecific rank. The use of the name since Santschi has not been associated with collected specimens, and as a result is ''
Red imported fire ant workers range in size from small to medium, making them polymorphic. Workers measure between . The head measures and is wide. In the larger workers (as in the major workers), their heads measure and wide. The antenna scapes measure and the 
The red imported ant can be misidentified as the similar-looking ''S. richteri''. The two species can be distinguished from each other through morphological examinations of the head, thorax, and postpetiole. In ''S. richteri'', the sides of the head are broadly elliptical and the cordate shape seen in the red imported fire ant is absent. The region of the occipital lobes that are situated nearby the midline and occipital excision appear more crease-like in ''S. richteri'' than it does in the red imported fire ant. The scapes of ''S. richteri'' are longer than they are in the red imported fire ant, and the pronotum has strong angulate shoulders. Such character is almost absent in the red imported fire ant. A shallow but sunken area is only known in the larger workers of ''S. richteri'', which is located in the posterior region of the dorsum of the pronotum. This feature is completely absent in larger red imported fire ant workers. The red imported fire ant's promesonotum is strongly convex, whereas this feature is weakly convex in ''S. richteri''. Upon examination, the base of the propodeum is elongated and straight in ''S. richteri'', while convex and shorter in the red imported fire ant. It also has a wide postpetiole with either straight or diverging sides. The postpetiole in ''S. richteri'' is narrower with converging sides. In ''S. richteri'', the transverse impression on the posterodorsal portion of the postpetiole is strong, but weak or absent in the red imported fire ant. As well as that, ''S. richteri'' workers are 15% larger than red imported fire ant workers, are blackish-brown, and have a yellow stripe on the dorsal side of the gaster.
The red imported fire ant is polymorphic with two different castes of workers: minor workers and major workers (soldiers). Like many ants that exhibit polymorphism, young, smaller ants do not forage and tend to the brood, instead, while the larger workers go out and forage. In incipient colonies, polymorphism does not exist, but instead they are occupied by monomorphic workers called "minims" or "nanitics". The average head-width in tested colonies increases during the first six months of development. In five-year-old colonies, the head width of minor workers decreases, but for major workers, the head-width remains the same. The total weight of a major worker is twice that of a minor worker when they first arrive, and by six months, major workers are four times heavier than minor workers. Once major workers develop, they can make up a large portion of the workforce, with as many as 35% being major workers in a single colony. This does not affect colony performance, as polymorphic colonies and nests with small workers produce broods at roughly the same rate, and polymorphism is not an advantage or disadvantage when food sources are not limited. However, polymorphic colonies are more energetically efficient, and under conditions where food is limited, polymorphism may provide a small advantage in brood production, but this depends on the levels of food stress.
As worker ants grow to larger sizes, the shape of the head changes, due to the head length growing at the same time as the total body length, and the head width may grow by 20%. The length of the antennae only grows slowly; the antennae may only grow 60% longer by the time the body doubles its length, thus the relative antennal length decreases by 20% as the length of the body doubles. All individual legs of the body are isometric with body length meaning that even when the length of the body doubles, the legs will also double. However, not all of the legs are the same length; the prothoracic portion accounts for 29% of leg length, the mesothoracic 31%, and the metathoracic 41%. The first two pairs of legs are of equal length to one another, whereas the final pair is longer. Overall, the morphological appearance of a worker changes dramatically when it grows larger. The head exhibits the greatest shape change and the height of the alinotum grows quicker than its length, where a height/length ratio of 0.27 in minor workers and 0.32 in major workers is seen. Due to this, larger workers tend to have a humped-shape and robust alinotum in contrast to smaller workers. No petiole segment exhibits any change in shape as the size of the body changes. The width of the gaster grows more rapidly than its length, where the width may be 96% of its length but increases to 106%.
Like other insects, the red imported fire ant breathes through a system of gas-filled tubes called 
The ant faces many respiratory challenges due to its highly variable environment, which can cause increased
Red imported fire ants are native to the tropical areas of Central and South America, where they have an expansive geographical range that extends from southeastern Peru to central Argentina, and to the south of Brazil. In contrast to its geographical range in North America, its range in South America is significantly different. It has an extremely long north–south range, but a very narrow east–west distribution. The northernmost record of the red imported fire ant is
Myrmicinae
Myrmicinae is a subfamily of ants, with about 140 extant genera; their distribution is cosmopolitan. The pupae lack cocoons. Some species retain a functional sting. The petioles of Myrmicinae consist of two nodes. The nests are permanent and ...
, it was described by Swiss entomologist Felix Santschi as a variant of '' S. saevissima'' in 1916. Its current specific name ''invicta'' was given to the ant in 1972 as a separate species. However, the variant and species were the same ant, and the name was preserved due to its wide use. Though South American in origin, the red imported fire ant has been accidentally introduced in Australia, New Zealand, several Asian and Caribbean countries, and the United States. The red imported fire ant is polymorphic, as workers appear in different shapes and sizes. The ant's colours are red and somewhat yellowish with a brown or black gaster, but males are completely black. Red imported fire ants are dominant in altered areas and live in a wide variety of habitats. They can be found in rain forests, disturbed areas, deserts, grasslands, alongside roads and buildings, and in electrical equipment. Colonies form large mounds constructed from soil with no visible entrances because foraging tunnels are built and workers emerge far away from the nest.
These ants exhibit a wide variety of behaviours, such as building rafts when they sense that water levels are rising. They also show necrophoric behaviour, where nestmates discard scraps or dead ants on refuse piles outside the nest. Foraging takes place on warm or hot days, although they may remain outside at night. Workers communicate by a series of semiochemicals and pheromones, which are used for recruitment, foraging, and defence. They are omnivore
An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nu ...
s and eat dead mammals, arthropods, insects, seeds, and sweet substances such as honeydew from hemiptera
Hemiptera (; ) is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from to arou ...
n insects with which they have developed relationships. Predators include arachnids, birds, and many insects including other ants, dragonflies, earwigs, and beetles. The ant is a host to parasites and to a number of pathogens, nematodes, and viruses, which have been viewed as potential biological control agents. Nuptial flight
Nuptial flight is an important phase in the reproduction of most ant, termite, and some bee species. It is also observed in some fly species, such as '' Rhamphomyia longicauda''.
During the flight, virgin queens mate with males and then land t ...
occurs during the warm seasons, and the alates may mate for as long as 30 minutes. Colony founding can be done by a single queen or a group of queens, which later contest for dominance once the first workers emerge. Workers can live for several months, while queens can live for years; colony numbers can vary from 100,000 to 250,000 individuals. Two forms of society in the red imported fire ant exist: polygynous colonies (nests with multiple queens) and monogynous colonies (nests with one queen).
Venom plays an important role in the ant's life, as it is used to capture prey or for defence. About 95% of the venom consists of water-insoluble piperidine alkaloids known as solenopsins, with the rest comprising a mixture of toxic proteins that can be particularly potent in sensitive humans. More than 14 million people are stung by them in the United States annually, where many are expected to develop allergies to the venom. Most victims experience intense burning and swelling, followed by the formation of sterile pustules
A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of thi ...
, which may remain for several days. However 0.6% to 6.0% of people may suffer from anaphylaxis
Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the follo ...
, which can be fatal if left untreated. Common symptoms include dizziness, chest pain, nausea, severe sweating, low blood pressure, loss of breath, and slurred speech. More than 80 deaths have been recorded from red imported fire ant attacks. Treatment depends on the symptoms; those who only experience pain and pustule formation require no medical attention, but those who suffer from anaphylaxis are given epinephrine
Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands and ...
s. Whole body extract immunotherapy is used to treat victims and is regarded as highly effective.
The ant is viewed as a notorious pest, causing billions of dollars in damage annually and impacting wildlife. The ants thrive in urban areas, so their presence may deter outdoor activities. Nests can be built under structures such as pavements and foundations, which may cause structural problems, or cause them to collapse. Not only can they damage or destroy structures, but red imported fire ants also can damage equipment and infrastructure and impact business, land, and property values. In agriculture, they can damage crops and machinery, and threaten pastures. They are known to invade a wide variety of crops, and mounds built on farmland may prevent harvesting. They also pose a threat to animals and livestock, capable of inflicting serious injury or killing them, especially young, weak, or sick animals. Despite this, they may be beneficial because they consume common pest insects on crops. Common methods of controlling these ants include baiting and fumigation; other methods may be ineffective or dangerous. Due to its notoriety and importance, the ant has become one of the most studied insects on the planet, even rivalling the western honey bee
The western honey bee or European honey bee (''Apis mellifera'') is the most common of the 7–12 species of honey bees worldwide. The genus name ''Apis'' is Latin for "bee", and ''mellifera'' is the Latin for "honey-bearing" or "honey carrying" ...
(''Apis mellifera'').
Etymology and common names
Thespecific epithet
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bo ...
of the red imported fire ant, ''invicta'', derives from Latin
Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
, and means "invincible" or "unconquered". The epithet originates from the phrase ''Roma invicta
''Roma invicta'' is a Latin phrase, meaning "unconquered Rome". It was an inspirational motto used until the Fall of the Western Roman Empire in 476 AD. This symbolic statement was later printed onto gold coins.
See also
* Roman Empire
...
'' ("unconquered Rome"), used as an inspirational quote until the fall of the Western Roman Empire
The fall of the Western Roman Empire (also called the fall of the Roman Empire or the fall of Rome) was the loss of central political control in the Western Roman Empire, a process in which the Empire failed to enforce its rule, and its va ...
in 476 AD. The generic
Generic or generics may refer to:
In business
* Generic term, a common name used for a range or class of similar things not protected by trademark
* Generic brand, a brand for a product that does not have an associated brand or trademark, other ...
name, '' Solenopsis'', translates as "appearance" or "face" from Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...
. It is a compound of two Ancient Greek words–''solen'', meaning "pipe" or "channel", and ''opsis'', meaning "appearance" or "sight". The ant is commonly known as the "red imported fire ant" (abbreviated as RIFA). The " fire ant" part is because of the burning sensation caused by its sting. Alternative names include: the "fire ant", "red ant" or "tramp ant". In Brazil, locals call the ant ''toicinhera'', which derives from the Portuguese word ''toicinho'' (pork fat).
Taxonomy
The red imported fire ant was first described by Swiss entomologist Felix Santschi in a 1916 journal article published by ''Physis''. Originally named ''Solenopsis saevissima wagneri'' from a syntype worker collected from Santiago del Estero
Santiago del Estero (, Spanish for ''Saint-James-Upon-The-Lagoon'') is the capital of Santiago del Estero Province in northern Argentina. It has a population of 252,192 inhabitants, () making it the twelfth largest city in the country, with a surf ...
, Argentina, Santschi believed the ant was a variant of '' S. saevissima''; the specific epithet, ''wagneri'', derives from the surname of E.R. Wagner, who collected the first specimens. The type material is currently housed in Naturhistorisches Museum Basel, Switzerland, but additional type workers are possibly housed in the Muséum national d'histoire naturelle
The French National Museum of Natural History, known in French as the ' (abbreviation MNHN), is the national natural history museum of France and a ' of higher education part of Sorbonne Universities. The main museum, with four galleries, is loc ...
, Paris. In 1930, American myrmecologist William Creighton reviewed the genus ''Solenopsis'' and reclassified the taxon as ''Solenopsis saevissima electra wagneri'' at infrasubspecific rank, noting that he could not collect any workers that referred to Santschi's original description. In 1952, the ''S. saevissima'' species complex was examined and, together with nine other species-group names, ''S. saevissima electra wagneri'' was synonymised with ''S. saevissima saevissima''. This reclassification was accepted by Australian entomologist George Ettershank in his revision of the genus and in Walter Kempf's 1972 catalogue of Neotropical ants.
In 1972, American entomologist William Buren described what he thought was a new species, naming it ''Solenopsis invicta''. Buren collected a holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...
worker from Cuiabá
Cuiabá () is the capital city of the Brazilian state of Mato Grosso. It is located near the geographical centre of South America. Also, it forms the metropolitan area of Mato Grosso, along with the neighbouring town of Várzea Grande. The city ...
in Mato Grosso
Mato Grosso ( – lit. "Thick Bush") is one of the states of Brazil, the third largest by area, located in the Central-West region. The state has 1.66% of the Brazilian population and is responsible for 1.9% of the Brazilian GDP.
Neighboring ...
, Brazil, and provided the first official description of the ant in a journal article published by the Georgia Entomological Society. He accidentally misspelled ''invicta'' as above the description pages of the species, although it was clear that ''invicta'' was the intended spelling because of the constant use of the name in the article. The type material is currently housed in the National Museum of Natural History
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7. ...
, Washington, D.C.
In a 1991 review of the species complex, American entomologist James Trager synonymised ''S. saevissima electra wagneri'' and ''S. wagneri'' together. Trager incorrectly cites ''Solenopsis saevissima electra wagneri'' as the original name, erroneously believing that the name ''S. wagneri'' was unavailable and used Buren's name ''S. invicta''. Trager previously believed that ''S. invicta'' was conspecific with ''S. saevissima'' until comparing the material with ''S. wagneri''. Trager notes that though ''S. wagneri'' has priority over ''S. invicta'', the name was never used above infrasubspecific rank. The use of the name since Santschi has not been associated with collected specimens, and as a result is ''nomen nudum
In taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published with an adequate desc ...
''. In 1995, English myrmecologist Barry Bolton
Barry Bolton is an English myrmecologist, an expert on the classification, systematics, and taxonomy of ants, who long worked at the Natural History Museum, London. He is known especially for monographs on African and Asian ants, and for encyclo ...
corrected Trager's error, recognising ''S. wagneri'' as the valid name and synonymised ''S. invicta''. He states that Trager wrongfully classified ''S. wagneri'' as an unavailable name and cites ''S. saevissima electra wagneri'' as the original taxon. He concludes that ''S. wagneri'' is, in fact, the original name and has priority over ''S. invicta''.
In 1999, Steve Shattuck and colleagues proposed conserving the name ''S. invicta''. Since the first description of ''S. invicta'', over 1,800 scientific papers using the name were published discussing a wide range of topics about its ecological behaviour, genetics, chemical communication, economic impacts, methods of control, population, and physiology. They state that the use of ''S. wagneri'' is a "threat" to nomenclatural stability towards scientists and non-scientists; taxonomists may have been able to adapt to such name change, but name confusion may arise if such case occurred. Due to this, Shattuck and his colleagues proposed the continued use of ''S. invicta'' and not ''S. wagneri'', as this name has been rarely used; between 1995 and 1998, over 100 papers were published using ''S. invicta'' and only three using ''S. wagneri''. They requested that the International Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries.
Orga ...
(ICZN) use plenary power
A plenary power or plenary authority is a complete and absolute power to take action on a particular issue, with no limitations. It is derived from the Latin term ''plenus'' ("full").
United States
In United States constitutional law, plenary p ...
s to suppress ''S. wagneri'' for the purpose of the Principle of Priority and not for the Principle of Homonymy. Furthermore, they requested that the name ''S. invicta'' be added to the Official List of Specific Names in Zoology and that ''S. wagneri'' be added to the Official Index of Rejected Invalid Specific Names in Zoology. Upon review, the proposal was voted on by the entomological community and was supported by all but one voter. They note that there is no justification in suppressing ''S. wagneri''; instead, it would be better to give precedence to ''S. invicta'' over ''S. wagneri'' whenever an author treated them as conspecific. The ICZN would conserve ''S. invicta'' and suppress ''S. wagneri'' in a 2001 review. Under the present classification, the red imported fire ant is a member of the genus ''Solenopsis'' in the tribe Solenopsidini, subfamily Myrmicinae
Myrmicinae is a subfamily of ants, with about 140 extant genera; their distribution is cosmopolitan. The pupae lack cocoons. Some species retain a functional sting. The petioles of Myrmicinae consist of two nodes. The nests are permanent and ...
. It is a member of the family Formicidae, belonging to the order Hymenoptera
Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic.
Females typic ...
, an order of insects containing ants, bee
Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfami ...
s, and wasp
A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...
s.
Phylogeny
The red imported fire ant is a member of the ''S. saevissima'' species-group. Members can be distinguished by their two-jointed clubs at the end of the funiculus in workers and queens, and the second and third segments of the funiculus are twice as long and broad in larger workers. Polymorphism occurs in all species and themandible
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...
s bear four teeth. The following cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...
shows the position of the red imported fire ant among other members of the ''S. saevissima'' species-group:
Phenotypic and genetic data suggest that the red imported fire ant and the black imported fire ant (''Solenopsis richteri'') differ from each other, but they do share a close genetic relationship. Hybridisation between the two ants occurs in areas where they make contact, with the hybrid zone located in Mississippi. Such hybridisation has resulted from secondary contact between these two ants several decades ago, when they first encountered each other in southern Alabama
(We dare defend our rights)
, anthem = " Alabama"
, image_map = Alabama in United States.svg
, seat = Montgomery
, LargestCity = Huntsville
, LargestCounty = Baldwin County
, LargestMetro = Greater Birmingham
, area_total_km2 = 135,7 ...
. Based on mitochondrial DNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
, examined haplotype
A haplotype ( haploid genotype) is a group of alleles in an organism that are inherited together from a single parent.
Many organisms contain genetic material ( DNA) which is inherited from two parents. Normally these organisms have their DNA o ...
s do not form a monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gr ...
clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...
. Some of the examined haplotypes form a closer relationship to '' S. megergates'', ''S. quinquecuspis'' and ''S. richteri'' than they do with other ''S. invicta'' haplotypes. The occurrence of a possible paraphyletic
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...
grouping suggests that the red imported fire ant and ''S. quinquecuspis'' are possible cryptic species groups composed of several species that cannot be distinguished morphologically.
Genetics
Studies show thatmitochondrial DNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
variation occurs substantially in polygyne societies (nests with multiple queens), but no variation is detected in monogyne societies (nests with a single queen). Triploidy
Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set conta ...
(a chromosomal abnormality) occurs in red imported fire ants at high rates (as high as 12% in non-reproductive females), which is linked to the high frequency of diploid males. The red imported fire ant is the first species shown to possess a green-beard gene, by which natural selection can favour altruistic behaviour. Workers containing this gene are able to distinguish between queens containing it, and those that do not, apparently by using odour cues. The workers kill queens that do not contain the gene. In 2011, scientists announced they had fully sequenced the red imported fire ant genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ...
from a male.
Description
Red imported fire ant workers range in size from small to medium, making them polymorphic. Workers measure between . The head measures and is wide. In the larger workers (as in the major workers), their heads measure and wide. The antenna scapes measure and the thoracic
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the crea ...
length is . The head becomes wider behind the eyes with rounded occipital lobes present, and unlike the similar-looking ''S. richteri'', the lobes peak further than the midline, but the occipital excision is not as crease-like. The scapes in major workers do not extend beyond occipital peak by one or two scape diameters; this feature is more noticeable in ''S. richteri''. In medium-sized workers, the scapes reach the occipital peaks and exceed the rear border in the smallest workers. In small and medium workers, the head tends to have more elliptical sides. The head of small workers is wider out front than it is behind. In the major workers, the pronotum
The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum ( dorsal), the prosternum (ventral), and the propleuron (lateral) on e ...
does not have any angular shoulders, nor does it have any sunken posteromedian area. The promesonotum is convex and the propodeum base is rounded and also convex. The base and declivity are of equal length. The suture
Suture, literally meaning "seam", may refer to:
Arts, entertainment, and media
* ''Suture'' (album), a 2000 album by American Industrial rock band Chemlab
* ''Suture'' (film), a 1993 film directed by Scott McGehee and David Siegel
* Suture (ban ...
of the promesonotum is either strong or weak in larger workers. The petiole has a thick and blunt scale; if observed from behind, it is not as rounded above in contrast to ''S. richteri'', and sometimes it may be subtruncate. The postpetiole is large and broad, and in the larger workers, it is broader than its length. The postpetiole tends to be less broad in front and broader behind. On the rear side of the dorsal surface, a transverse impression is present. In ''S. richteri'', this feature is also present but much weaker.
The sculpture is very similar to ''S. richteri''. The punctures are from where pilosity arises, and these are often elongated on the dorsal and ventral portions of the head. On the thorax, striae are present, but they are less engraved with fewer punctures than in ''S. richteri''. On the petiole, the punctates are located on the sides. The postpetiole, when viewed above, has a strong shagreen with distinct transverse punctostriae. The sides are covered in deep punctures, where they appear smaller but deeper. In ''S. richteri'', the punctures are larger and more shallow. This gives a more opaque appearance to the surface. In some cases, punctostriae may be present around the rear portion. The pilosity appears similar to that of ''S. richteri''. These hairs are erect and vary in length, appearing long on each side of the pronotum
The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum ( dorsal), the prosternum (ventral), and the propleuron (lateral) on e ...
and mesonotum; on the head, the long hairs are seen in longitudinal rows. Numerous appressed pubescent hairs are on the petiolar scale; this is the opposite in ''S. richteri'', as these hairs are sparse. Workers appear red and somewhat yellowish with a brown or completely black gaster. Gastric spots are sometimes seen in larger workers, where they are not as brightly coloured as those in ''S. richteri''. The gastric spot usually covers a small portion of the first gastric tergite. The thorax is concolorous, ranging from light reddish-brown to dark-brown. The legs and coxae are usually lightly shaded. The head has a consistent colour pattern in large workers, with the occiput and vertex
Vertex, vertices or vertexes may refer to:
Science and technology Mathematics and computer science
*Vertex (geometry), a point where two or more curves, lines, or edges meet
*Vertex (computer graphics), a data structure that describes the position ...
appearing brown. Other parts of the head, including the front, genae, and the central region of the clypeus, are either yellowish or yellowish brown. The anterior borders of the genae and mandibles are dark-brown; they also both appear to share the same coloured shade with the occiput. The scapes and funiculi range from being the same colour as the head or shares the same shade with the occiput. Light-coloured areas of the head in small to medium-sized workers is restricted to only the frontal region, with a dark mark resembling an arrow or rocket being present. On occasion, nests may have a series of different colours. For example, workers may be much darker, and the gastric spot may be completely absent or appear dark-brown.
Queens have a head length of and a width of . The scapes measure and the thorax is . The head is almost indistinguishable from ''S. richteri'', but the occipital excision is less crease-like and the scapes are considerably shorter. Its petiolar scale is convex and resembles that of ''S. richteri''. The postpetiole has straight sides that never concave, unlike in ''S. richteri'' where they concave. The thorax is almost identical, but the clear space between the metapleural striate area and propodeal spiracles is either a narrow crease or not present. The side portions of the petiole are punctate. The sides of the postpetiole are opaque
Opacity or opaque may refer to:
* Impediments to (especially, visible) light:
** Opacities, absorption coefficients
** Opacity (optics), property or degree of blocking the transmission of light
* Metaphors derived from literal optics:
** In lingui ...
with punctures present, but no irregular roughening is seen. The anterior of the dorsum is shagreen, and the middle and rear regions bear transverse puncto-striae. All these regions have erect hairs. The anterior portions of both the petiole and postpetiole have appressed pubescence that is also seen on the propodeum. The colour of the queen is similar to that of a worker: the gaster is dark brown and the legs, scapes, and thorax are light brown with dark streaks on the mesoscutum. The head is yellowish or yellowish-brown around the central regions, the occiput and mandibles are a similar colour to the thorax, and the wing veins range from colourless to pale brown. Males appear similar to ''S. richteri'', but the upper borders of the petiolar scales are more concave. In both species, the postpetiole's and petiole's spiracles strongly project. The whole body of the male is concolorous black, but the antennae are whitish. Like the queen, the wing veins are colourless or pale brown.
The red imported ant can be misidentified as the similar-looking ''S. richteri''. The two species can be distinguished from each other through morphological examinations of the head, thorax, and postpetiole. In ''S. richteri'', the sides of the head are broadly elliptical and the cordate shape seen in the red imported fire ant is absent. The region of the occipital lobes that are situated nearby the midline and occipital excision appear more crease-like in ''S. richteri'' than it does in the red imported fire ant. The scapes of ''S. richteri'' are longer than they are in the red imported fire ant, and the pronotum has strong angulate shoulders. Such character is almost absent in the red imported fire ant. A shallow but sunken area is only known in the larger workers of ''S. richteri'', which is located in the posterior region of the dorsum of the pronotum. This feature is completely absent in larger red imported fire ant workers. The red imported fire ant's promesonotum is strongly convex, whereas this feature is weakly convex in ''S. richteri''. Upon examination, the base of the propodeum is elongated and straight in ''S. richteri'', while convex and shorter in the red imported fire ant. It also has a wide postpetiole with either straight or diverging sides. The postpetiole in ''S. richteri'' is narrower with converging sides. In ''S. richteri'', the transverse impression on the posterodorsal portion of the postpetiole is strong, but weak or absent in the red imported fire ant. As well as that, ''S. richteri'' workers are 15% larger than red imported fire ant workers, are blackish-brown, and have a yellow stripe on the dorsal side of the gaster.
Brood
Eggs are tiny and oval-shaped, remaining the same size for around a week. After one week, the egg assumes the shape of an embryo and forms as a larva when the egg shell is removed. Larvae measure . They show a similar appearance to '' S. geminata'' larvae, but they can be distinguished by the integument with spinules on top of the dorsal portion of the posterior somites. The body hairs measure with a denticulate tip. The antennae both have two or threesensilla
A sensillum (plural ''sensilla'') is an arthropod sensory organ protruding from the cuticle of exoskeleton, or sometimes lying within or beneath it. Sensilla appear as small hairs or pegs over an individual's body. Inside each sensillum there are ...
. The labrum is smaller with two hairs on the anterior surface that are . The maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...
has a sclerotised band between the cardo and stipes. The labium
Labium is the Latin word for lip. In English, it may refer to:
* Labia, a part of the female external genitalia
* Labium (botany), a modified petal in certain monocot flowers, which attracts insects for pollination
* Labium (arthropod mouthpart), ...
also has a small sclerotised band. The tubes of the labial gland
The labial glands are minor salivary glands situated between the mucous membrane and the orbicularis oris around the orifice of the mouth.
They are circular in form, and about the size of small peas; their ducts open by minute orifices upon the mu ...
s are known to produce or secrete a proteinaceous substance that has a rich level of digestive enzymes, which includes proteases and amylases that function as an extraintestinal digestion of solid food. The midgut also contains amylases, roteases and upases. The narrow cells in its reservoir have little to no function in secretion. The pupae resemble adults of any caste, except that their legs and antennae are held tightly against the body. They appear white, but over time, the pupae turns darker when they are almost ready to mature.
Four larval instar
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ...
s have been described based on distinctive morphological characters. The larvae of the minor and major workers are impossible to distinguish before the final instar, when size differences become apparent. Upon pupation a wider head width difference between castes become more evident. Reproductive larvae are larger than worker larvae, and present discrete morphological differences in mouthparts. Fourth-instar larvae of males and queens can be differentiated based on their relative shape and body coloration, and also internal gonopodal imaginal discs can differ.
Polymorphism
The red imported fire ant is polymorphic with two different castes of workers: minor workers and major workers (soldiers). Like many ants that exhibit polymorphism, young, smaller ants do not forage and tend to the brood, instead, while the larger workers go out and forage. In incipient colonies, polymorphism does not exist, but instead they are occupied by monomorphic workers called "minims" or "nanitics". The average head-width in tested colonies increases during the first six months of development. In five-year-old colonies, the head width of minor workers decreases, but for major workers, the head-width remains the same. The total weight of a major worker is twice that of a minor worker when they first arrive, and by six months, major workers are four times heavier than minor workers. Once major workers develop, they can make up a large portion of the workforce, with as many as 35% being major workers in a single colony. This does not affect colony performance, as polymorphic colonies and nests with small workers produce broods at roughly the same rate, and polymorphism is not an advantage or disadvantage when food sources are not limited. However, polymorphic colonies are more energetically efficient, and under conditions where food is limited, polymorphism may provide a small advantage in brood production, but this depends on the levels of food stress.
As worker ants grow to larger sizes, the shape of the head changes, due to the head length growing at the same time as the total body length, and the head width may grow by 20%. The length of the antennae only grows slowly; the antennae may only grow 60% longer by the time the body doubles its length, thus the relative antennal length decreases by 20% as the length of the body doubles. All individual legs of the body are isometric with body length meaning that even when the length of the body doubles, the legs will also double. However, not all of the legs are the same length; the prothoracic portion accounts for 29% of leg length, the mesothoracic 31%, and the metathoracic 41%. The first two pairs of legs are of equal length to one another, whereas the final pair is longer. Overall, the morphological appearance of a worker changes dramatically when it grows larger. The head exhibits the greatest shape change and the height of the alinotum grows quicker than its length, where a height/length ratio of 0.27 in minor workers and 0.32 in major workers is seen. Due to this, larger workers tend to have a humped-shape and robust alinotum in contrast to smaller workers. No petiole segment exhibits any change in shape as the size of the body changes. The width of the gaster grows more rapidly than its length, where the width may be 96% of its length but increases to 106%.
Physiology
Like other insects, the red imported fire ant breathes through a system of gas-filled tubes called tracheae
The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends from the la ...
connected to the external environment through spiracles. The terminal tracheal branches ( tracheoles) make direct contact with internal organs and tissue. The transport of oxygen to cells (and carbon dioxide out of cells) occurs through diffusion
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical ...
of gases between the tracheoles and the surrounding tissue and is assisted by a discontinuous gas exchange. As with other insects, the direct communication between the tracheal system and tissues eliminates the need for a circulating fluid network to transport O2. Thus, red imported fire ants and other arthropods can have a modest circulatory system though they have highly expensive metabolic demands.
The excretory system consists of three regions. The basal region has three cells found within the posterior portion of the midgut. The anterior and superior cavities are formed by the bases of four Malpighian tubules. The superior cavity opens into the lumen of the small intestine. The rectum is a large but thin-walled sac that occupies the posterior fifth of the larvae. The release of waste is controlled by the rectal valves that lead to the anus. Sometimes, the larvae secrete a liquid that consists of uric acid
Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates, such as ammonium acid urate. Uric acid is a product of the metabolic breakdown ...
, water and salts. These contents are often carried outside by workers and ejected, but colonies under water stress may consume the contents. In the reproductive system
The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are ...
, queens release a pheromone that prevents dealation and oogenesis
Oogenesis, ovogenesis, or oögenesis is the differentiation of the ovum (egg cell) into a cell competent to further develop when fertilized. It is developed from the primary oocyte by maturation. Oogenesis is initiated in the embryonic stage.
...
in virgin females; those tested in colonies without a queen begin oocyte
An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ...
development after dealation and take up the egg-laying role. Flight muscle degeneration is initiated by mating and juvenile hormones, and prevented by corpus allatectomy. Histolysis begins with the dissolution of the myofibril
A myofibril (also known as a muscle fibril or sarcostyle) is a basic rod-like organelle of a muscle cell. Skeletal muscles are composed of long, tubular cells known as muscle fibers, and these cells contain many chains of myofibrils. Each myofi ...
and the slow breakdown of the myofilaments. Such dissolution continues until it reaches the only free Z-line materials, which would also disappear; only the nuclei and lamellar bodies remain. In one study, the amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
s increase in the hemolymph
Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...
after insemination.
The glandular system contains four glands: the mandibular, maxillary, labial, and postpharyngeal glands. The postpharyngeal is well developed in the queen, while the other glands are larger in workers. The postpharyngeal gland functions as a vacuum to absorb fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, f ...
s and triglyceride
A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from ''tri-'' and ''glyceride'').
Triglycerides are the main constituents of body fat in humans and other vertebrates, as ...
s, as well as a gastric caecum
The cecum or caecum is a pouch within the peritoneum that is considered to be the beginning of the large intestine. It is typically located on the right side of the body (the same side of the body as the appendix, to which it is joined). The wo ...
. The functions of the other glands remain poorly understood. In one study discussing the enzymes of the digestion system of adult ants, lipase
Lipase ( ) is a family of enzymes that catalyzes the hydrolysis of fats. Some lipases display broad substrate scope including esters of cholesterol, phospholipids, and of lipid-soluble vitamins and sphingomyelinases; however, these are usually ...
activity was found in the mandibular and labial glands, as well as invertase
Invertase is an enzyme that catalyzes the hydrolysis (breakdown) of sucrose (table sugar) into fructose and glucose. Alternative names for invertase include , saccharase, glucosucrase, beta-h-fructosidase, beta-fructosidase, invertin, sucrase, m ...
activity. The Dufour's gland found in the ant acts as a source of trail pheromones, although scientists believed the poison gland was the source of the queen pheromone. The neurohormone pheromone biosynthesis activating neuropeptide is found in the ant that activates the biosynthesis of pheromones from the Dufour's gland. The spermatheca gland is found in queens, which functions in sperm maintenance. Males appear to lack these glands, but those associated with its head are morphologically similar to those found in workers, but these glands may act differently.
The ant faces many respiratory challenges due to its highly variable environment, which can cause increased desiccation
Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container.
...
, hypoxia, and hypercapnia
Hypercapnia (from the Greek ''hyper'' = "above" or "too much" and ''kapnos'' = "smoke"), also known as hypercarbia and CO2 retention, is a condition of abnormally elevated carbon dioxide (CO2) levels in the blood. Carbon dioxide is a gaseous p ...
. Hot, humid climates cause an increase in heart rate and respiration which increases energy and water loss. Hypoxia and hypercapnia can result from red imported fire ant colonies living in poorly ventilated thermoregulatory
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperatur ...
mounds and underground nests. Discontinuous gas exchange (DGE) may allow ants to survive the hypercapnic and hypoxic conditions frequently found in their burrows; it is ideal for adapting to these conditions because it allows the ants to increase the period of O2 intake and CO2 expulsion independently through spiracle manipulation. The invasion success of the red imported fire ant may possibly be related to its physiological tolerance to abiotic stress, being more heat tolerant and more adaptable to desiccation stress than ''S. richteri''. This means that the ant is less vulnerable to heat and desiccation stress. Although ''S. richteri'' has higher water body content than the red imported fire ant, ''S. richteri'' was more vulnerable to desiccation stress. The lower sensitivity to desiccation is due to a lower water loss rate. Colonies living in unshaded and warmer sites tend to have a higher heat tolerance than those living in shaded and cooler sites.
Metabolic rate, which indirectly affects respiration, is also influenced by environmental temperature. Peak metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run ...
occurs at about 32 °C. Metabolism, and therefore respiration rate, increases consistently as temperature increases. DGE stops above 25 °C, although the reason for this is currently unknown.
Respiration rate also appears to be influenced significantly by caste. Males show a considerably higher rate of respiration than females and workers, due, in part, to their capability for flight and higher muscle mass. In general, males have more muscle and less fat, resulting in a higher metabolic O2 demand.
While the metabolic rate is highest at 32 °C, colonies often thrive at slightly cooler temperatures (around 25 °C). The high rate of metabolic activity associated with warmer temperatures is a limiting factor on colony growth because the need for food consumption is also increased. As a result, larger colonies tend to be found in cooler conditions because the metabolic demands required to sustain a colony are decreased.
Distribution and habitat
Red imported fire ants are native to the tropical areas of Central and South America, where they have an expansive geographical range that extends from southeastern Peru to central Argentina, and to the south of Brazil. In contrast to its geographical range in North America, its range in South America is significantly different. It has an extremely long north–south range, but a very narrow east–west distribution. The northernmost record of the red imported fire ant is Porto Velho
Porto Velho (, ''Old Port'') is the capital of the Brazilian state of Rondônia, in the upper Amazon River basin, and a Catholic Metropolitan Archbishopric. The population is 548,952 people (as of the IBGE 2021 estimation). Located on the border of ...
in Brazil, and its southernmost record is Resistencia in Argentina; this is a distance of about . In comparison, the width of its narrow range is about , and this is most likely narrower into southern Argentina and Paraguay and into the northern areas of the Amazon River basin. Most known records of the red imported fire ant are around the Pantanal region of Brazil. However, the interior of this area has not been examined thoroughly, but it is certain that the species occurs in favourable locations around it. The Pantanal region is thought to be the original homeland of the red imported fire ant; hydrochore dispersal via floating ant rafts could easily account for the far south populations around the Paraguay
Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to t ...
and Guaporé River
Guaporé River ( pt, Rio Guaporé, es, Río Iténez) is a river in western Brazil and northeastern Bolivia. It is long; of the river forms the border between Brazil and Bolivia.
The Guaporé River is part of the Madeira River basin, which eve ...
s. The western extent of its range is not known exactly, but its abundance there may be limited. It may be extensive in easternmost Bolivia, owing to the presence of the Pantanal region.
These ants are native to Argentina, and the red imported fire ant most likely came from here when they first invaded the United States; in particular, populations of these ants have been found in the provinces of Chaco, Corrientes
Corrientes (; Guaraní: Taragüí, literally: "Currents") is the capital city of the province of Corrientes, Argentina, located on the eastern shore of the Paraná River, about from Buenos Aires and from Posadas, on National Route 12. It ha ...
, Formosa
Taiwan, officially the Republic of China (ROC), is an island country located in East Asia. The main island of Taiwan, formerly known in the Western political circles, press and literature as Formosa, makes up 99% of the land area of the territori ...
, Santiago del Estero
Santiago del Estero (, Spanish for ''Saint-James-Upon-The-Lagoon'') is the capital of Santiago del Estero Province in northern Argentina. It has a population of 252,192 inhabitants, () making it the twelfth largest city in the country, with a surf ...
, Santa Fe, and Tucumán. The northeastern regions of Argentina are the most credible guess where the invading ants originate. In Brazil, they are found in northern Mato Grosso and in Rondônia
Rondônia () is one of the 26 states of Brazil, located in the northern subdivision of the country (central-western part). To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso ...
and in São Paulo state. The red imported fire ant and ''S. saevissima'' are parapatric in Brazil, with contact zones known in Mato Grosso do Sul
Mato Grosso do Sul () is one of the Midwestern states of Brazil. Neighboring Brazilian states are (from north clockwise) Mato Grosso, Goiás, Minas Gerais, São Paulo and Paraná. It also borders the countries of Paraguay, to the southwest, and ...
, Paraná state Paraná, Paranã or Parana may refer to:
Geology
*Paraná Basin, a sedimentary basin in South America
Places In Argentina
*Paraná, Entre Ríos, a city
*Paraná Department, a part of Entre Ríos Province
* Paraná, Buenos Aires, a settlement ...
and São Paulo. In Paraguay they are found throughout the country, and have been recorded in Boquerón, Caaguazú, Canindeyú, Central
Central is an adjective usually referring to being in the center of some place or (mathematical) object.
Central may also refer to:
Directions and generalised locations
* Central Africa, a region in the centre of Africa continent, also known a ...
, Guairá, Ñeembucú, Paraguarí
Paraguarí (; gn, Paraguari) is a city, '' distrito'' and capital of Paraguarí Department in Paraguay, located 66 km from the country's capital, Asunción. At the 2002 census it had a population of 22,154.Presidente Hayes departments; Trager claims that the ant is distributed in all regions of the country. They are also found in a large portion of northeastern Bolivia and, to a lesser extent, in northwestern Uruguay.
The red imported fire ant is able to dominate altered areas and live in a variety of habitats. It can survive the extreme weather of the South American rain forest, and in disturbed areas, nests are seen frequently alongside roads and buildings. The ant has been observed frequently around the
Red imported fire ants are among the worst invasive species in the world. Some scientists consider the red imported fire ant to be a "disturbance specialist"; human disturbance to the environment may be a major factor behind the ants' impact (fire ants tend to favour disturbed areas). This is shown through one experiment, demonstrating that mowing and plowing in studied areas diminished the diversity and abundance of native ant species, whereas red imported fire ants found on undisturbed forest plots had only diminished a couple of species.
In the United States, the red imported fire ant first arrived in the seaport of 
Red imported fire ants have spread beyond North America. The
Red imported fire ants are extremely resilient and have adapted to contend with both flooding and drought conditions. If the ants sense increased water levels in their nests, they link together and form a ball or raft that floats, with the workers on the outside and the queen inside. The brood is transported to the highest surface. They are also used as the founding structure of the raft, except for the eggs and smaller larvae. Before submerging, the ants will tip themselves into the water and sever connections with the dry land. In some cases, workers may deliberately remove all males from the raft, resulting in the males drowning. The longevity of a raft can be as long as 12 days. Ants that are trapped underwater escape by lifting themselves to the surface using bubbles which are collected from submerged substrate. Owing to their greater vulnerability to predators, red imported fire ants are significantly more aggressive when rafting. Workers tend to deliver higher doses of venom, which reduces the threat of other animals attacking. Due to this, and because a higher workforce of ants is available, rafts are potentially dangerous to those that encounter them.
Necrophoric behaviour occurs in the red imported fire ant. Workers discard uneaten food and other such wastes away from the nest. The active component was not identified, but the fatty acids accumulating as a result of decomposition were implicated and bits of paper coated with synthetic
Colonies of the red imported fire ant have tunneling surfaces that protrude out of the surfaces where workers forage. These areas of protrusion tend to be within their own territory, but greater ant colonisation can affect this. Tunnels are designed to allow effective body, limb and antennae interactions with walls, and a worker can also move exceptionally fast inside them (more than nine bodylengths per second). The holes exit out of any point within the colony's territory, and foraging workers may need to travel half a metre to reach the surface. Assuming the average forager travels 5 m, over 90% of foraging time is inside the tunnels during the day and rarely at night. Workers forage in soil temperatures reaching 27 °C (80 °F) and surface temperatures of 12–51 °C (53–123 °F). Workers exposed to temperatures of 42 °C (107 °F) are at risk of dying from the heat. The rate of workers foraging drops rapidly by autumn, and they rarely emerge during winter. This may be due to the effects of soil temperature, and a decreased preference for food sources. These preferences only decrease when brood production is low. In the northern regions of the United States, areas are too cold for the ant to forage, but in other areas such as Florida and
Red imported fire ants are
A number of insects,
Flies in the genus '' Pseudacteon'' (phorid flies) are known to be parasitic to ants. Some species within this genus, such as Pseudacteon tricuspis, have been introduced into the environment for the purpose of controlling the imported fire ant. These flies are
As soon as the first individuals reach the pupal stage, the queen ceases egg production until the first workers mature. This process takes two weeks to one month. The young larvae are fed oils which are regurgitated from her crop, as well as 
The life expectancy of a worker ant depends on its size, although the overall average is around 62 days. Minor workers are expected to live for about 30 to 60 days, whereas the larger workers live much longer. Larger workers, which have a life expectancy of 60 to 180 days, live 50–140% longer than their smaller counterparts, but this depends on the temperature. However, workers kept in laboratory conditions have been known to live for 10 to 70 weeks (70 days to 490 days); the maximum recorded longevity of a worker is 97 weeks (or 679 days). The queens live much longer than the workers, with a lifespan ranging from two years to nearly seven years.
In colonies, queens are the only ants able to alter sex ratios which can be predicted. For example, queens originating from male-producing colonies tend to produce predominantly males, while queens that came from female-favoured sex ratio colonies tend to produce females. Queens also exert control over the production of sexuals through pheromones that influence the behaviours of workers toward both male and female larvae.
When polygyne forms invade areas where colonies have not yet been established, the diversity of native
Red imported fire ants have formed a relationship with an invasive
Because of their notoriety and invasive behaviour, red imported fire ants are considered
The red imported fire ant is a significant agricultural pest in areas where it is not native. They are capable of damaging crops, and they threaten pastures and
Several baits have been used to control populations. Mounds are destroyed in a matter of weeks if baits are used on them. Baits are considered to be effective and simple to use against red imported fire ants, in comparison to drenching, dusting, or fumigating. They are sprinkled onto the mound then the ants take and consume them. Certain baits such as growth regulator baits, and boric acid-sucrose water baits, benefit native fauna and low concentrations are usually required to kill a colony. Others baits used against red imported fire ants include Amdro, Ascend,
Books and journals about the red imported fire ant
at
Books and journals about the red imported fire ant
at
National Red Imported Fire Ant Eradication Program
– Queensland Department of Agriculture and Fisheries
Imported Fire Ants
– United States Department of Agriculture
''Solenopsis invicta'' at the AntWiki – Bringing Ants to the WorldThe ''S. invicta'' Genome Project
– Hymenoptera Genome Database project
Species Profile - Red Imported Fire Ant (''Solenopsis invicta'')
National Invasive Species Information Center,
Footage of phorid flies parasitising fire ants
– Captured by BBC, published by the University of Texas at Austin College of Natural Sciences
Red Fire Ants
– published by National Geographic at YouTube
Casting a Fire Ant Colony with Molten Aluminum
at YouTube
– ''The Washington Post'', 2011 {{DEFAULTSORT:Red Imported Fire Ant Solenopsis (ant) Hymenoptera of Asia Hymenoptera of Australia Hymenoptera of North America Hymenoptera of South America Insects described in 1916 Insects described in 1972 Scavengers Agricultural pest insects Biological pest control insects Insects used as insect pest control agents Pest insects Household pest insects
floodplains
A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
of the Paraguay River. In areas where water is present, they are commonly found around: irrigation channels, lakes, ponds, reservoirs, rivers, streams, riverbanks, and mangrove swamps. Nests are found in agricultural areas, coastlands, wetlands, coastal dune remnants, deserts, forests, grasslands, natural forests, oak woodland, mesic forest
In ecology, a mesic habitat is a type of habitat with a moderate or well-balanced supply of moisture, e.g., a mesic forest, a temperate hardwood forest, or dry-mesic prairie. Mesic habitats transition to xeric shrublands in a non-linear fashion, ...
, leaf-litter, beach margins, shrublands, alongside rail and roads, and in urban areas. In particular, they are found in cultivated land, managed forests and plantations, disturbed areas, intensive livestock production systems, and greenhouses. Red imported fire ants have been found to invade buildings, including medical facilities. In urban areas, colonies dwell in open areas, especially if the area is sunny. This includes: urban gardens, picnic areas, lawns, playgrounds, schoolyards, parks, and golf courses. In some areas, there are on average 200 mounds per acre. During winter, colonies move under pavements or into buildings, and newly mated queens move into pastures. Red imported fire ants are mostly found at altitudes between above sea level.
Mounds range from small to large, measuring in height and in diameter with no visible entrances. Workers are only able to access their nests thorugh a series of tunnels that protrude from the central region. Such protrusions can span up to 25 feet away from the central mound, either straight down in to the ground or, more commonly, sideways from the original mound. Constructed from soil, mounds are oriented so that the long portions of the mound face toward the sun during the early morning and before sunset. Mounds are usually oval-shaped with the long axis of the nest orientating itself in a north–south direction. These ants also spend large amounts of energy in nest construction and transporting brood, which is related with thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperatur ...
. The brood is transported to areas where temperatures are high; workers track temperature patterns of the mound and do not rely on behavioural habits. Inside nests, mounds contain a series of narrow horizontal tunnels, with subterranean shafts and nodes reaching grass roots below the surface; these shafts and nodes connect the mound tunnels to the subterranean chambers. These chambers are about 5 cm2 (0.77 inch2) and reach depths of . The mean number of ants in a single subterranean chamber is around 200.
Introductions
Red imported fire ants are among the worst invasive species in the world. Some scientists consider the red imported fire ant to be a "disturbance specialist"; human disturbance to the environment may be a major factor behind the ants' impact (fire ants tend to favour disturbed areas). This is shown through one experiment, demonstrating that mowing and plowing in studied areas diminished the diversity and abundance of native ant species, whereas red imported fire ants found on undisturbed forest plots had only diminished a couple of species.
In the United States, the red imported fire ant first arrived in the seaport of Mobile, Alabama
Mobile ( , ) is a city and the county seat of Mobile County, Alabama, United States. The population within the city limits was 187,041 at the 2020 census, down from 195,111 at the 2010 census. It is the fourth-most-populous city in Alabama ...
, by cargo ship between 1933 and 1945. Arriving with an estimated 9 to 20 unrelated queens, the red imported fire ant was only rare at the time, as entomologists were unable to collect any specimens (with the earliest observations first made in 1942, preceded by a population expansion in 1937); the population of these ants exploded by the 1950s. Since its introduction to the United States, the red imported fire ant has spread throughout the southern states and northeastern Mexico, negatively affecting wildlife and causing economic damage. The expansion of red imported fire ants may be limited since they are almost wiped out during Tennessee
Tennessee ( , ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. Tennessee is the List of U.S. states and territories by area, 36th-largest by ...
winters, thus they may be reaching their northernmost range. However, global warming may allow the red imported fire ant to expand its geographical range. As of 2004, the ant is found in 13 states and occupies over 128 million hectares of land, and as many as 400 mounds can be found on a single acre of land. The United States Department of Agriculture
The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of comme ...
estimates that they expand westward per year. Likely due to absence of South American competitors - and lower numbers of native competitors - ''S. invicta'' dominates more extrafloral nectaries
Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualis ...
and hemiptera
Hemiptera (; ) is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from to arou ...
n honeydew sources in the southern USA than in its home range.
Red imported fire ants were first discovered in Queensland
)
, nickname = Sunshine State
, image_map = Queensland in Australia.svg
, map_caption = Location of Queensland in Australia
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, establishe ...
, Australia, in 2001. The ants were believed to be present in shipping containers arriving at the Port of Brisbane
Port of Brisbane is the shipping port and coastal suburb of the City of Brisbane, on the east coast of Queensland, Australia. In the , Port of Brisbane had no residents living in the suburb. The port is the largest in the state of Queensland.
...
, most likely from North America. Anecdotal evidence suggests fire ants may have been present in Australia for six to eight years prior to formal identification. The potential damage from the red imported fire ant prompted the Australian government to respond rapidly. A joint state and federal funding of A$175 million was granted for a six-year eradication programme. Following years of eradication, eradication rates of greater than 99% from previously infested properties were reported. The program received extended Commonwealth
A commonwealth is a traditional English term for a political community founded for the common good. Historically, it has been synonymous with "republic". The noun "commonwealth", meaning "public welfare, general good or advantage", dates from the ...
funding of around A$10 million for at least another two years to treat the residual infestations found most recently. In December 2014, a nest was identified at Port Botany, Sydney
Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mounta ...
, in New South Wales
)
, nickname =
, image_map = New South Wales in Australia.svg
, map_caption = Location of New South Wales in AustraliaCoordinates:
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, es ...
. The port was quarantined, and a removal operation took place. In September 2015, populations originating from the United States were found at a Brisbane airport.
Red imported fire ants have spread beyond North America. The Invasive Species Specialist Group
Invasive may refer to:
* Invasive (medical) procedure
* Invasive species
* Invasive observation, especially in reference to surveillance
Surveillance is the monitoring of behavior, many activities, or information for the purpose of informati ...
(ISSG) reports the ant inhabiting from three of the Cayman Islands
The Cayman Islands () is a self-governing British Overseas Territory—the largest by population in the western Caribbean Sea. The territory comprises the three islands of Grand Cayman, Cayman Brac and Little Cayman, which are located to the ...
. However, the sources the ISSG cited give no report about them on the island, but recent collections indicate that they are present. In 2001, red imported fire ants were discovered in New Zealand, but they were successfully eradicated several years later. Red imported fire ants have been reported in India, Malaysia, the Philippines and Singapore. However, these reports were found to be incorrect as the ants collected there were incorrectly identified as the red imported fire ant. In Singapore, the ants were most likely misidentified as well. In India, surveyed ants in Sattur Taluk, India listed the red imported fire ant there in high populations; meanwhile, no reports of the ant were made outside the surveyed area. In 2016, scientists state that despite no presence of the ant in India, the red imported fire ant will more than likely find suitable habitats within India's ecosystem if given the opportunity. The reports in the Philippines most likely misidentified collected material as the red imported fire ant, as no populations have been found there. It was discovered in Hong Kong
Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a List of cities in China, city and Special administrative regions of China, special ...
and mainland China in 2004, where they have spread into several provinces as well as Macau
Macau or Macao (; ; ; ), officially the Macao Special Administrative Region of the People's Republic of China (MSAR), is a city and special administrative region of China in the western Pearl River Delta by the South China Sea. With a pop ...
and Taiwan. No geographic or climatic barriers prevent these ants from spreading further, thus it may spread throughout the tropical and subtropical regions of Asia. In Europe, a single nest was found in the Netherlands in 2002.
Around 1980, red imported fire ants began spreading throughout the West Indies
The West Indies is a subregion of North America, surrounded by the North Atlantic Ocean and the Caribbean Sea that includes 13 independent island countries and 18 dependencies and other territories in three major archipelagos: the Greate ...
, where they were first reported in Puerto Rico
Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...
and the U.S. Virgin Islands. Between 1991 and 2001, the ant was recorded from Trinidad and Tobago, several areas in the Bahamas, the British Virgin Islands, Antigua, and the Turks and Caicos Islands. Since then, red imported fire ants have been recorded on more islands and regions, with new populations discovered in: Anguilla
Anguilla ( ) is a British Overseas Territory in the Caribbean. It is one of the most northerly of the Leeward Islands in the Lesser Antilles, lying east of Puerto Rico and the Virgin Islands and directly north of Saint Martin. The terr ...
, Saint Martin, Barbuda
Barbuda (), is an island located in the eastern Caribbean forming part of the sovereign state of Antigua and Barbuda. It is located north of the island of Antigua and is part of the Leeward Islands of the West Indies. The island is a popula ...
, Montserrat
Montserrat ( ) is a British Overseas Territory in the Caribbean. It is part of the Leeward Islands, the northern portion of the Lesser Antilles chain of the West Indies. Montserrat is about long and wide, with roughly of coastline. It is n ...
, Saint Kitts
Saint Kitts, officially the Saint Christopher Island, is an island in the West Indies. The west side of the island borders the Caribbean Sea, and the eastern coast faces the Atlantic Ocean. Saint Kitts and the neighbouring island of Nevis cons ...
, Nevis
Nevis is a small island in the Caribbean Sea that forms part of the inner arc of the Leeward Islands chain of the West Indies. Nevis and the neighbouring island of Saint Kitts constitute one country: the Federation of Saint Kitts and ...
, Aruba
Aruba ( , , ), officially the Country of Aruba ( nl, Land Aruba; pap, Pais Aruba) is a constituent country of the Kingdom of the Netherlands physically located in the mid-south of the Caribbean Sea, about north of the Venezuela peninsula of P ...
, and Jamaica. The ants recorded from Aruba and Jamaica have only been found on golf courses; these courses import sod from Florida
Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
, so such importation may be an important way for the ant to spread throughout the West Indies.
Populations found outside North America originate from the United States. In 2011, the DNA of specimens from Australia, China, and Taiwan was analysed with results showing that they are related to those in the United States. Despite its spread, ''S. geminata'' has a greater geographical range than the red imported fire ant, but it can be easily displaced by it. Because of this, almost all of its exotic range in North America has been lost and the ant has almost disappeared there. On roadsides in Florida, 83% of these sites had ''S. geminata'' present when the red imported fire ant was absent, but only 7% when it is present. This means that the ant can probably invade many tropical and subtropical regions where ''S. geminata'' populations are present.
Behaviour and ecology
Red imported fire ants are extremely resilient and have adapted to contend with both flooding and drought conditions. If the ants sense increased water levels in their nests, they link together and form a ball or raft that floats, with the workers on the outside and the queen inside. The brood is transported to the highest surface. They are also used as the founding structure of the raft, except for the eggs and smaller larvae. Before submerging, the ants will tip themselves into the water and sever connections with the dry land. In some cases, workers may deliberately remove all males from the raft, resulting in the males drowning. The longevity of a raft can be as long as 12 days. Ants that are trapped underwater escape by lifting themselves to the surface using bubbles which are collected from submerged substrate. Owing to their greater vulnerability to predators, red imported fire ants are significantly more aggressive when rafting. Workers tend to deliver higher doses of venom, which reduces the threat of other animals attacking. Due to this, and because a higher workforce of ants is available, rafts are potentially dangerous to those that encounter them.
Necrophoric behaviour occurs in the red imported fire ant. Workers discard uneaten food and other such wastes away from the nest. The active component was not identified, but the fatty acids accumulating as a result of decomposition were implicated and bits of paper coated with synthetic oleic acid
Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish. In chemical terms, oleic acid is classified as a monounsaturated o ...
typically elicited a necrophoric response. The process behind this behaviour in imported red fire ants was confirmed by Blum (1970): unsaturated fats, such as oleic acid, elicit corpse-removal behaviour. Workers also show differentiated responses towards dead workers and pupae. Dead workers are usually taken away from the nest, whereas the pupae may take a day for a necrophoric response to occur. Pupae infected by ''Metarhizium anisopliae
''Metarhizium robertsii'' formerly known as ''M. anisopliae'', and even earlier as ''Entomophthora anisopliae'' (basionym) is a fungus that grows naturally in soils throughout the world and causes disease in various insects by acting as a paras ...
'' are usually discarded by workers at a higher rate; 47.5% of unaffected corpses are discarded within a day, but for affected corpses this figure is 73.8%.
Red imported fire ants have negative impacts on seed germination
Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fe ...
. The extent of the damage, however, depends on how long seeds are vulnerable for (dry and germinating) and by the abundance of the ants. One study showed that while these ants are attracted to and remove seeds which have adapted for ant dispersal, red imported fire ants damage these seeds or move them in unfavourable locations for germination. In seeds given to colonies, 80% of '' Sanguinaria canadensi'' seeds were scarified and 86% of '' Viola rotundifolia'' seeds were destroyed. Small percentages of longleaf pine (''Pinus palustris'') seeds deposited by workers successfully germinate, thus providing evidence that red imported fire ants help the movement of seeds in the longleaf pine ecosystem. Elaiosome-bearing seeds are collected at a higher rate in contrast to nonelaiosome-bearing seeds and do not store them in their nests, but rather in surface trash piles in the mound vicinity.
Foraging and communication
Colonies of the red imported fire ant have tunneling surfaces that protrude out of the surfaces where workers forage. These areas of protrusion tend to be within their own territory, but greater ant colonisation can affect this. Tunnels are designed to allow effective body, limb and antennae interactions with walls, and a worker can also move exceptionally fast inside them (more than nine bodylengths per second). The holes exit out of any point within the colony's territory, and foraging workers may need to travel half a metre to reach the surface. Assuming the average forager travels 5 m, over 90% of foraging time is inside the tunnels during the day and rarely at night. Workers forage in soil temperatures reaching 27 °C (80 °F) and surface temperatures of 12–51 °C (53–123 °F). Workers exposed to temperatures of 42 °C (107 °F) are at risk of dying from the heat. The rate of workers foraging drops rapidly by autumn, and they rarely emerge during winter. This may be due to the effects of soil temperature, and a decreased preference for food sources. These preferences only decrease when brood production is low. In the northern regions of the United States, areas are too cold for the ant to forage, but in other areas such as Florida and Texas
Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...
, foraging may occur all year round. When it is raining, workers do not forage outside, as exit holes are temporarily blocked, pheromone trails are washed away, and foragers may be physically struck by the rain. The soil's moisture may also affect the foraging behaviour of workers.
When workers are foraging, it is characterised by three steps: searching, recruitment, and transportation. Workers tend to search for honey more often than other food sources, and the weight of food has no impact on searching time. Workers may recruit other nestmates if the food they have found is too heavy, taking as much as 30 minutes for the maximum number of recruited workers to arrive. Lighter food sources take less time and are usually transported rapidly. Foraging workers become scouts and search solely for food outside the surface, and may subsequently die two weeks later from old age.
Workers communicate by a series of semiochemicals and pheromones. These communication methods are used in a variety of activities, such as nestmate recruitment, foraging, attraction, and defence; for example, a worker may secrete trail pheromones if a food source it discovered is too large to carry. These pheromones are synthesized by the Dufour's gland and may trail from the discovered food source back to the nest. The components in these trail pheromones are also species-specific to this ant only, in contrast to other ants with common tail pheromones. The poison sack in this species has been identified as being the novel storage site of the queen pheromone; this pheromone is known to elicit orientation in worker individuals, resulting in the deposition of brood. It is also an attractant, where workers aggregate toward areas where the pheromone has been released. A brood pheromone is possibly present, as workers are able to segregate brood by their age and caste, which is followed by licking, grooming and antennation. If a colony is under attack, workers will release alarm pheromones. However, these pheromones are poorly developed in workers. Workers can detect pyrazine
Pyrazine is a heterocyclic aromatic organic compound with the chemical formula C4H4N2. It is a symmetrical molecule with point group D2h. Pyrazine is less basic than pyridine, pyridazine and pyrimidine. It is a ''"deliquescent crystal or wax-li ...
s which are produced by the alates; these pyrazines may be involved in nuptial flight
Nuptial flight is an important phase in the reproduction of most ant, termite, and some bee species. It is also observed in some fly species, such as '' Rhamphomyia longicauda''.
During the flight, virgin queens mate with males and then land t ...
, as well as an alarm response.
Red imported fire ants can distinguish nestmates and non-nestmates through chemical communication and specific colony odours. Workers prefer to dig into nest materials from their own colony and not from soil in unnested areas or from other red imported fire ant colonies. One study suggests that as a colony's diet is similar, the only difference between nested and unnested soil was the nesting of the ants themselves. Therefore, workers may transfer colony odour within the soil. Colony odour can be affected by the environment, as workers in lab-reared colonies are less aggressive than those in the wild. Queen-derived cues are able to regulate nestmate recognition in workers and amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent ...
levels. However, these cues do not play a major role in colony-level recognition, but they can serve as a form of caste-recognition within nests. Workers living in monogyne societies tend to be extremely aggressive and attack intruders from neighbouring nests. In queenless colonies, the addition of alien queens or workers does not increase aggression among the population.
Diet
Red imported fire ants are omnivore
An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nu ...
s, and foragers are considered to be scavenger
Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feedin ...
s rather than predators. The ants' diet consists of dead mammals, arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...
s, insects, earthworms, vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with ...
s, and solid food matter such as seeds. However, this species prefers liquid over solid food. The liquid food the ants collect is sweet substances from plants or honeydew-producing hemiptera
Hemiptera (; ) is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from to arou ...
ns. Arthropod prey may include diptera
Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
n adults, larvae and pupae, and termite
Termites are small insects that live in colonies and have distinct castes ( eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blat ...
s. The consumption of sugar amino acid is known to affect recruitment of workers to plant nectars. Mimic plants with sugar rarely have workers to feed on them, whereas those with sugar and amino acids have considerable numbers. The habitats where they live may determine the food they collect the most; for example, forage success rates for solid foods are highest in lakeshore sites, while high levels of liquid sources were collected from pasture sites. Specific diets can also alter the growth of a colony, with laboratory colonies showing high growth if fed honey-water. Colonies that feed on insects and sugar-water can grow exceptionally large in a short period of time, whereas those that do not feed on sugar-water grow substantially slower. Colonies that do not feed on insects cease brood production entirely. Altogether, the volume of food digested by nestmates is regulated within colonies. Larvae are able to display independent appetites for sources such as solid proteins, amino acid solutions, and sucrose solutions, and they also prefer these sources over dilute solutions. Such behaviour is due to their capability to communicate hunger to workers. The rate of consumption depends on the type, concentration, and state of the food on which they feed. Workers tend to recruit more nestmates to food sources filled with high levels of sucrose than to protein.
Food distribution plays an important role in a colony. This behaviour varies in colonies, with small workers receiving more food than larger workers if a small colony is seriously deprived of food. In larger colonies, however, the larger workers receive more food. Workers can donate sugar water efficiently to other nestmates, with some acting as donors. These "donors" distribute their food sources to recipients, which may also act as donors. Workers may also share a greater portion of their food with other nestmates. In colonies that are not going through starvation, food is still distributed among the workers and larvae. One study shows that honey and soybean oil were fed to the larvae after 12 to 24 hours of being retained by the workers. The ratio distribution of these food sources was 40% towards the larvae and 60% towards the worker for honey, and for soybean oil this figure was around 30 and 70%, respectively. Red imported fire ants also stockpile specific food sources such as insect pieces rather than consuming them immediately. These pieces are usually transported below the mound surface and in the driest and warmest locations.
This species engages in trophallaxis with the larvae. Regardless of the attributes and conditions of each larva, they are fed roughly the same amount of liquid food. The rate of trophallaxis may increase with larval food deprivation, but such increase depends on the size of each larva. Larvae that are fed regularly tend to be given small amounts. To reach satiation, all larvae regardless of their size generally require the equivalent of eight hours of feeding.
Predators
A number of insects, arachnid
Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegar ...
s, and birds prey on these ants, especially when queens are trying to establish a new colony. While in the absence of defending workers, the fire ant queens must rely on their venom to keep off competitor species Many species of dragonfly
A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat thre ...
, including '' Anax junius'', '' Pachydiplax longipennis'', '' Somatochlora provocans'', and '' Tramea carolina'', capture the queens while they are in flight; 16 species of spiders, including the wolf spider '' Lycosa timuga'' and the southern black widow spider (''Latrodectus mactans''), actively kill red imported fire ants. ''L. mactans'' captures all castes of the species (the workers, queens, and males) within its web. These ants constitute 75% of prey captured by the spider. Juvenile ''L. mactans'' spiders have also been seen capturing the ants. Other invertebrates that prey on red imported fire ants are earwigs (''Labidura riparia
''Labidura riparia'' is a species of earwig in the family Labiduridae characterized by their modified cerci as forceps, and light tan color.Tawfik, M., Abul-Nar, S., and El-hussein, M. 1973. The biology of ''Labidura riparia'' Pallas. Bulletin ...
'') and tiger beetles ('' Cicindela punctulata''). Birds that eat these ants include the chimney swift (''Chaetura pelagica''), the eastern kingbird (''Tyrannus tyrannus''), and the eastern bobwhite (''Colinus virginianus virginianus''). The eastern bobwhite attacks these ants by digging out the mounds looking for young queens. Red imported fire ants have been found in stomach contents inside of armadillo
Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, alo ...
s.
Many species of ants have been observed attacking queens and killing them. Apparently, the venom of fire ant queens is chemically adapted to rapidly subdue offending competitor ants. Predatory ants include: '' Ectatomma edentatum'', '' Ephebomyrmex'' spp., ''Lasius neoniger
''Lasius neoniger'', also known as the turfgrass ant, Labour day ant, cornfield ant or nuisance ant, is a species of ant in the genus ''Lasius''. Found in North America, the species is common in the eastern United States and Canada, though they ...
'', '' Pheidole'' spp., ''Pogonomyrmex badius
''Pogonomyrmex badius'', or the Florida harvester ant, is a species of harvester ant in the genus ''Pogonomyrmex''. It is the only ''Pogonomyrmex'' species found on the east coast of the United States and the only one in North America known to b ...
,'' and '' Conomyrma insana'', which is among the most significant. ''C. insana'' ants are known to be effective predators against founding queens in studied areas of Northern Florida. The pressure of attacks initiated by ''C. insana'' increase over time, causing queens to exhibit different reactions, including escaping, concealment, or defence. Most queens that are attacked by these ants are ultimately killed. Queens that are in groups have higher chances of survival than solitary queens if they are attacked by ''S. geminata''. Ants can attack queens on the ground and invade nests by stinging and dismembering them. Other ants such as '' P. porcula'' try to take the head and gaster, and '' C. clara'' invade in groups. Also, certain ants try to drag queens out of their nests by pulling on the antennae or legs. Small, monomorphic ants rely on recruitment to kill queens and do not attack them until reinforcements arrive. Aside from killing the queen, some ants may steal the eggs for consumption or emit a repellent that is effective against red imported fire ants. Certain ant species may raid colonies and destroy them.
Parasites, pathogens and viruses
Flies in the genus '' Pseudacteon'' (phorid flies) are known to be parasitic to ants. Some species within this genus, such as Pseudacteon tricuspis, have been introduced into the environment for the purpose of controlling the imported fire ant. These flies are parasitoid
In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...
s of the red imported fire ant in its native range in South America, and can be attracted through the ants' venom alkaloids. One species, '' Pseudacteon obtusus'', attacks the ant by landing on the posterior portion of the head and laying an egg. The location of the egg makes it impossible for the ant to successfully remove it. The larvae migrate to the head, then develop by feeding on the hemolymph
Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...
, muscle tissue, and nervous tissue. After about two weeks, they cause the ant's head to fall off by releasing an enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
that dissolves the membrane attaching the head to its body. The fly pupates in the detached head capsule, emerging two weeks later. '' P. tricuspis'' is another phorid fly that is a parasitoid to this species. Although parasitism pressures by these flies do not affect the ants' population density and activity, it has a small effect on a colony population. The strepsipteran insect '' Caenocholax fenyesi'' is known to infect male ants of this species and attack the eggs, and the mite
Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear e ...
''Pyemotes tritici
''Pyemotes tritici'' is a species of mite known as the grain itch mite or straw itch mite. It is a cosmopolitan species that is found on straw, hay and stored grain. It is a parasite of small arthropods and is being investigated as a possible bi ...
'' has been considered a potential biological agent against red imported fire ants, capable of parasitising every caste within the colony. Bacteria, such as ''Wolbachia
''Wolbachia'' is a genus of intracellular bacteria that infects mainly arthropod species, including a high proportion of insects, and also some nematodes. It is one of the most common parasitic microbes, and is possibly the most common reproducti ...
'', has been found in the red imported fire ant; three different variants of the bacteria are known to infect the red imported fire ant. However, its effect on the ant is unknown. '' Solenopsis daguerrei'' is a reproductive parasite to red imported fire ant colonies.
A large variety of pathogens and nematodes also infect red imported fire ants. Pathogens include '' Myrmecomyces annellisae'', '' Mattesia'' spp., '' Steinernema'' spp., a mermithid nematode, ''Vairimorpha invictae
''Vairimorpha'' is a genus of microsporidian parasites.
Species include:
* ''Vairimorpha cheracis'' - a parasite of the Australian freshwater crayfish, ''Cherax destructor''
* ''Vairimorpha disparis'' - a parasite of the moth, ''Lymantria disp ...
'', which can be transmitted via live larvae and pupae and dead adults and '' Tetradonema solenopsis'', which can be fatal to a large portion of a colony. Individuals infected by ''Metarhizium anisopliae
''Metarhizium robertsii'' formerly known as ''M. anisopliae'', and even earlier as ''Entomophthora anisopliae'' (basionym) is a fungus that grows naturally in soils throughout the world and causes disease in various insects by acting as a paras ...
'' tend to perform trophallaxis more frequently and have an enhanced preference to quinine
Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to '' Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...
, an alkaloid substance. Phorid flies with ''Kneallhazia solenopsae
''Kneallhazia solenopsae'' is a unique pathogenic intracellular microsporidium, that infects two of the fire ant species: the red ''Solenopsis invicta'' and the black '' Solenopsis richteri'' in North and South America.
''Kneallhazia solenopsae' ...
'' can serve as vectors in transmitting the disease to the ants. Weakening the colony, infections from this disease are localised within the body fat, with spores only occurring in adult individuals. The mortality of an infected colony tends to be greater in contrast to those that are healthy. These ants are a host to '' Conidiobolus'', '' Myrmicinosporidium durum,'' and ''Beauveria bassiana
''Beauveria bassiana'' is a fungus that grows naturally in soils throughout the world and acts as a parasite on various arthropod species, causing white muscardine disease; it thus belongs to the entomopathogenic fungi. It is used as a biologic ...
'', each of which are parasitic fungi. Infected individuals have spores all over their bodies and appear darker than usual. The toxicity from antimicrobial property of volatiles produced by the ants can significantly reduce the germination rate of ''B. bassiana'' within the colony.
A virus, ''S. invicta 1'' ( SINV-1), has been found in about 20% of fire ant fields, where it appears to cause the slow death of infected colonies. It has proven to be self-sustaining and transmissible. Once introduced, it can eliminate a colony within three months. Researchers believe the virus has potential as a viable biopesticide to control fire ants. Two more viruses have also been discovered: ''S. invicta'' 2 (SINV-2) and ''S. invicta'' 3 (SINV-3). Polygynous
Polygyny (; from Neoclassical Greek πολυγυνία (); ) is the most common and accepted form of polygamy around the world, entailing the marriage of a man with several women.
Incidence
Polygyny is more widespread in Africa than in any ...
colonies tend to face greater infections in contrast to monogynous
This is a glossary of terms used in the descriptions of ants.
A
B
D
E
F
G
H
M
N
O
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Q
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U
W
See also
...
colonies. Multiple virus infections can also occur.
Lifecycle and reproduction
Nuptial flight
Nuptial flight is an important phase in the reproduction of most ant, termite, and some bee species. It is also observed in some fly species, such as '' Rhamphomyia longicauda''.
During the flight, virgin queens mate with males and then land t ...
in red imported fire ants begins during the warmer seasons of the year (spring and summer), usually two days after rain. The time alates emerge and mate is between noon and 3:00pm. Nuptial flights recorded in North Florida have, on average, 690 female and male alates participating in a single flight. Males are the first to leave the nest, and both sexes readily undertake flight with little to no preflight activity. However, workers swarm the mound excitedly stimulated by mandibular glands within the head of the alates. As mounds do not have holes, workers form holes during nuptial flight as a way for the alates to emerge. This behaviour in workers, elicited by the pheromones, includes rapid running and back-and-forth movements, and increased aggression. Workers also cluster themselves around the alates as they climb up on vegetation, and in some cases, attempt to pull them back down before they take flight. Chemical cues from males and females during nuptial flight attract workers, but chemical cues released by workers do not attract other nestmates. It also induces alarm-recruitment behaviour in workers which results in a higher rate of alate retrieval.
Males fly at higher elevations than females: captured males are usually above the surface, whereas the females are only above the surface. A nuptial flight takes place for roughly half an hour and females generally fly for less than before landing. About 95% of queens successfully mate and only mate once; some males may be infertile due to the testicular lobes failing to develop. In polygyne colonies, males do not play a significant role and most are, therefore, sterile; one of the reasons for this is to avoid mating with other ant species. This also makes male mortality selective, which may affect the breeding system, mating success and, gene flow
In population genetics, gene flow (also known as gene migration or geneflow and allele flow) is the transfer of genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent a ...
. Ideal conditions for a nuptial flight to begin is when humidity levels are above 80% and when the soil temperature is above 18 °C (64 °F). Nuptial flights only occur when the ambient temperature is 24–32 °C (75–89 °F).
Queens are often found 1–2.3 miles from the nest they flew from.
Colony founding can be done by an individual or in groups, known as pleometrosis. This joint effort of the co-foundresses contributes to the growth and survival of the incipient colony; nests founded by multiple queens begin the growth period with three times as many workers when compared to colonies founded by a single queen. Despite this, such associations are not always stable. The emergence of the first workers instigates queen-queen and queen-worker fighting. In pleometrotic conditions, only one queen emerges victorious, whereas the queens that lost are subsequently killed by the workers. The two factors that could affect the survival of individual queens are their relative fighting capabilities and their relative contribution to worker production. Size, an indicator of fighting capacity, positively correlates with survival rates. However, manipulation of the queen's relative contribution to worker production had no correlation with survival rate.
A single queen lays around 10 to 15 eggs 24 hours after mating. In established nests, a queen applies venom onto each egg that perhaps contains a signal calling for workers to move it. These eggs remain unchanged in size for one week until they hatch into larvae. By this time, the queen will have laid about 75 to 125 more eggs. The larvae that hatch from their eggs are usually covered in their shell membranes for several days. The larvae can free their mouthparts from their shells using body movements, but still need assistance from workers with hatching. The larval stage is divided into four instar
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ...
s, as observed through the moulting stages. At the end of each moult, a piece of unknown material is seen connected to the exuvia
In biology, exuviae are the remains of an exoskeleton and related structures that are left after ecdysozoans (including insects, crustaceans and arachnids) have moulted. The exuviae of an animal can be important to biologists as they can often b ...
e if they are isolated from the workers. The larval stage lasts between six and 12 days before their bodies expand significantly and become pupae; the pupal stage lasts between nine and 16 days.
As soon as the first individuals reach the pupal stage, the queen ceases egg production until the first workers mature. This process takes two weeks to one month. The young larvae are fed oils which are regurgitated from her crop, as well as trophic egg A trophic egg, in most species that produce them, usually is an unfertilised egg because its function is not reproduction but nutrition; in essence it serves as food for offspring hatched from viable eggs. The production of trophic eggs has been ob ...
s or secretions. She also feeds the young her wing muscles, providing the young with needed nutrients. The first generation of workers are always small because of the limit of nutrients needed for development. These workers are known as minims or nanitics, which burrow out of the queen's chamber and commence foraging for food needed for the colony. Mound construction also occurs at this time. Within a month after the first generation is born, larger workers (major workers) start to develop, and within six months, the mound will be noticeable, if viewed, and houses several thousand residents. A mature queen is capable of laying 1,500 eggs per day; all workers are sterile, so cannot reproduce.
A colony can grow exceptionally fast. Colonies that housed 15–20 workers in May grew to over 7,000 by September. These colonies started to produce reproductive ants when they were a year old, and by the time they were two years old, they had over 25,000 workers. The population doubled to 50,000 when these colonies were three years old. At maturity, a colony can house 100,000 to 250,000 individuals, but other reports suggest that colonies can hold more than 400,000. Polygyne colonies have the potential to grow much larger than monogyne colonies.
Several factors contribute to colony growth. Temperature plays a major role in colony growth and development; colony growth ceases below 24 °C and developmental time decreases from 55 days at temperatures of 24 °C to 23 days at 35 °C. Growth in established colonies only occurs at temperatures between 24 and 36 °C. Nanitic brood also develops far quicker than minor worker brood (around 35% faster), which is beneficial for founding colonies. Colonies that have access to an unlimited amount of insect prey are known to grow substantially, but this growth is further accelerated if they are able to access plant resources colonised by hemiptera
Hemiptera (; ) is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from to arou ...
n insects. In incipient monogyne colonies where diploid males are produced, colony mortality rates are significantly high and colony growth is slow. In some cases, monogyne colonies experience 100% mortality rates in the early stages of development.
The life expectancy of a worker ant depends on its size, although the overall average is around 62 days. Minor workers are expected to live for about 30 to 60 days, whereas the larger workers live much longer. Larger workers, which have a life expectancy of 60 to 180 days, live 50–140% longer than their smaller counterparts, but this depends on the temperature. However, workers kept in laboratory conditions have been known to live for 10 to 70 weeks (70 days to 490 days); the maximum recorded longevity of a worker is 97 weeks (or 679 days). The queens live much longer than the workers, with a lifespan ranging from two years to nearly seven years.
In colonies, queens are the only ants able to alter sex ratios which can be predicted. For example, queens originating from male-producing colonies tend to produce predominantly males, while queens that came from female-favoured sex ratio colonies tend to produce females. Queens also exert control over the production of sexuals through pheromones that influence the behaviours of workers toward both male and female larvae.
Monogyny and polygyny
There are two forms of society in the red imported fire ant: polygynous colonies and monogynous colonies. Polygynous colonies differ substantially from monogynous colonies insocial insects
Eusociality (from Greek εὖ ''eu'' "good" and social), the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping gen ...
. The former experience reductions in queen fecundity
Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to pr ...
, dispersal, longevity, and nestmate relatedness. Polygynous queens are also less physogastric than monogynous queens and workers are smaller. Understanding the mechanisms behind queen recruitment is integral to understanding how these differences in fitness are formed. It is unusual that the number of older queens in a colony does not influence new queen recruitment. Levels of queen pheromone, which appears to be related to queen number, play important roles in the regulation of reproduction. It would follow that workers would reject new queens when exposed to large quantities of this queen pheromone. Moreover, evidence supports the claim that queens in both populations enter nests at random, without any regard for the number of older queens present. There is no correlation between the number of older queens and the number of newly recruited queens. Three hypotheses have been posited to explain the acceptance of multiple queens into established colonies: mutualism, kin selection
Kin selection is the evolutionary strategy that favours the reproductive success of an organism's relatives, even when at a cost to the organism's own survival and reproduction. Kin altruism can look like altruistic behaviour whose evolution ...
, and parasitism
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
. The mutualism hypothesis states that cooperation leads to an increase in the personal fitness of older queens. However, this hypothesis is not consistent with the fact that increasing queen number decreases both queen production and queen longevity. Kin selection also seems unlikely given that queens have been observed to cooperate under circumstances where they are statistically unrelated. Therefore, queens experience no gain in personal fitness by allowing new queens into the colony. Parasitism of preexisting nests appears to be the best explanation of polygyny. One theory is that so many queens attempt to enter the colony that the workers get confused and inadvertently allow several queens to join it.
Monogyne workers kill foreign queens and aggressively defend their territory. However, not all behaviours are universal, primarily because worker behaviours depend on the ecological context in which they develop, and the manipulation of worker genotypes can elicit change in behaviours. Therefore, behaviours of native populations can differ from those of introduced populations. In a study to assess the aggressive behaviour of monogyne and polygyne red fire ant workers by studying interaction in neutral arenas, and to develop a reliable ethogram for readily distinguishing between monogyne and polygyne colonies of red imported fire ants in the field, monogyne and polygyne workers discriminated between nestmates and foreigners as indicated by different behaviours ranging from tolerance to aggression. Monogyne ants always attacked foreign ants independently if they were from monogyne or polygyne colonies, whereas polygyne ants recognised, but did not attack, foreign polygyne ants, mainly by exhibiting postures similar to behaviours assumed after attacks by ''Pseudacteon'' phorids. Hostile versus warning behaviours were strongly dependent on the social structure of workers. Therefore, the behaviour toward foreign workers was a method of characterising monogyne and polygyne colonies. Most colonies in the southeastern and south-central US tend to be monogynous.
The monogynous red imported fire ant colony territorial area and the mound size are positively correlated, which, in turn, is regulated by the colony size (number and biomass of workers), distance from neighbouring colonies, prey density, and by the colony's collective competitive ability. In contrast, nestmate discrimination among polygynous colonies is more relaxed as workers tolerate conspecific
Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species.
Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organis ...
ants alien to the colony, accept other heterozygote
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism.
M ...
queens, and do not aggressively protect their territory from polygyne conspecifics. These colonies might increase their reproductive output as a result of having many queens and the possibility of exploiting greater territories by means of cooperative recruitment and interconnected mounds.
A social chromosome is present in the red imported fire ant. This chromosome can differentiate the social organisation of a colony carrying one of two variants of a supergene
A supergene is a chromosomal region encompassing multiple neighboring genes that are inherited together because of close genetic linkage, i.e. much less recombination than would normally be expected. This mode of inheritance can be due to genom ...
(B and b) which contains more than 600 gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
s. The social chromosome has often been compared to sexual chromosomes because they share similar genetic features and they define colony phenotype in a similar way. For example, colonies exclusively carrying the B variant of this chromosome accept single BB queens, but colonies with both B and b variants will accept multiple Bb queens only. Differences in another single gene can also determine whether the colony will have single or multiple queens.
Relationship with other animals
Competition
When polygyne forms invade areas where colonies have not yet been established, the diversity of native arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...
s and vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with ...
s declines greatly. This is evident as populations of isopods, mites and tumblebug scarabs decline significantly. They can also significantly alter the populations of many fly and beetle families, including: Calliphoridae
The Calliphoridae (commonly known as blow flies, blow-flies, carrion flies, bluebottles, greenbottles, or cluster flies) are a family of insects in the order Diptera, with almost 1,900 known species. The maggot larvae, often used as fishing ba ...
, Histeridae, Muscidae, Sarcophagidae, Silphidae, and Staphylinidae
The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, th ...
. Despite this, one review found that certain insects may be unaffected by red imported fire ants; for example, the density of isopods decreases in red imported fire ant infested areas, but crickets of the genus '' Gryllus'' are unaffected. There are some cases where the diversity of certain insect and arthropod species increase in areas where red imported fire ants are present. Red imported fire ants are important predators on cave invertebrates, some of which are endangered species. This includes harvestmen, pseudoscorpions, spiders, ground
beetles, and pselaphid beetles. The biggest concern is not the ant itself, but the bait used to treat them because this can prove fatal. Stock Island tree snails (''Orthalicus reses'') are extinct in the wild; predation by red imported fire ants is believed to be the major factor in the snail's extinction. Overall, red imported fire ants prefer specific arthropods to others, although they attack and kill any invertebrate that cannot defend itself or escape. Arthropod biodiversity increases once red imported fire ant populations are either reduced or eradicated.
Interactions between red imported fire ants and mammals have been rarely documented. However, deaths of live-trapped animals by red imported fire ants have been observed. Mortality rates in eastern cottontail (''Sylvilagus floridanus'') young range from 33 to 75% because of red imported fire ants. It is believed that red imported fire ants have a strong impact on many herpetofauna species; scientists have noted population declines in the Florida kingsnake
''Lampropeltis getula floridana'' or the Florida kingsnake is a snake subspecies native to southern Florida. On average, they grow between 3.5–5 ft but 6 ft individuals have been recorded.
Care
Like other kingsnakes, this species i ...
(''Lampropeltis getula floridana''), and eggs and adults of the eastern fence lizard (''Sceloporus undulatus'') and six-lined racerunner (''Aspidoscelis sexlineata'') are a source of food. Because of this, eastern fence lizards have adapted to have longer legs and new behaviours to escape the red imported fire ant. Additionally, another lizard species, '' Sphaerodactylus macrolepis'' are also a target of the fire ants' and have developed tactics to fend them off, such as tail flicks. Adult three-toed box turtle
The three-toed box turtle (''Terrapene triunguis'') is a species within the genus of hinge-shelled turtles commonly referred to as box turtles. This species is native to the south-central part of the United States and is the official reptile of ...
s (''Terrapene carolina triunguis''), Houston toad (''Anaxyrus houstonensis'') juveniles, and American alligator
The American alligator (''Alligator mississippiensis''), sometimes referred to colloquially as a gator or common alligator, is a large crocodilian reptile native to the Southeastern United States. It is one of the two extant species in the gen ...
(''Alligator mississippiensis'') hatchling
In oviparous biology, a hatchling is a newly hatched fish, amphibian, reptile, or bird. A group of mammals called monotremes lay eggs, and their young are hatchlings as well.
Fish
Fish hatchlings generally do not receive parental care, similar to ...
s are also attacked and killed by these ants. Despite this mostly-negative association, one study shows that red imported fire ants may be capable of impacting vector-borne disease transmissions by regulating tick populations and altering vector and host dynamics, thereby reducing transmission rates not only to animals, but to humans as well.
Mortality rates have been well observed in birds; there have been instances where no young have survived to adulthood in areas with high fire ant density. Many birds including cliff nesting swallows, ducks, egret
Egrets ( ) are herons, generally long-legged wading birds, that have white or buff plumage, developing fine plumes (usually milky white) during the breeding season. Egrets are not a biologically distinct group from herons and have the same buil ...
s, quail
Quail is a collective name for several genera of mid-sized birds generally placed in the order Galliformes. The collective noun for a group of quail is a flock, covey, or bevy.
Old World quail are placed in the family Phasianidae, and New ...
, and tern
Terns are seabirds in the family Laridae that have a worldwide distribution and are normally found near the sea, rivers, or wetlands. Terns are treated as a subgroup of the family Laridae which includes gulls and skimmers and consists of e ...
s have been affected by red imported fire ants. Ground nesting birds, particularly the least tern (''Sterna antillarum''), are vulnerable to fire ant attacks. The impact of red imported fire ants on colonial breeding birds is especially severe; waterbird
A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term ''water bird'' is especially applied to birds in freshwater ecosystems, although others make no distinction from sea ...
s can experience a mortality rate of 100%, although this factor was lower for early-nesting birds. Brood survival decreases in American cliff swallow
The cliff swallow or American cliff swallow (''Petrochelidon pyrrhonota'') is a member of the passerine bird family Hirundinidae, the swallows and martins. The generic name ''Petrochelidon'' is derived from Ancient Greek ''petros'' meaning "ro ...
s (''Petrochelidon pyrrhonota'') if they are exposed to foraging workers. Songbird
A songbird is a bird belonging to the suborder Passeri of the perching birds (Passeriformes). Another name that is sometimes seen as the scientific or vernacular name is Oscines, from Latin ''oscen'', "songbird". The Passeriformes contains 5000 ...
nest survival decreases in areas with red imported fire ants present, but survival rates in white-eyed vireo (''Vireo griseus'') and black-capped vireo (''Vireo atricapilla'') nests increase from 10% to 31% and 7% to 13% whenever fire ants are not present or when they are unable to attack them. Red imported fire ants may indirectly contribute to low brood survival in the Attwater's prairie chicken. It was first thought that the ants were linked to the decline of overwintering birds such as the loggerhead shrike
The loggerhead shrike (''Lanius ludovicianus'') is a passerine bird in the family Laniidae. It is the only member of the shrike family endemic to North America; the related northern shrike (''L. borealis'') occurs north of its range, however it ...
(''Lanius ludovicianus''), but a later study showed that ant eradication efforts using the pesticide Mirex, which was known to have toxic side effects, was largely to blame.
Red imported fire ants are strong competitors with many ant species. They have managed to displace many native ants which has led to a number of ecological consequences. However, studies show that these ants are not always superior competitors that suppress native ants. Habitat disturbance prior to their arrival, and recruitment limitations, are more plausible reasons why native ants are suppressed. Between '' Tapinoma melanocephalum'' and '' Pheidole fervida'', the red imported fire ant is stronger than both species but shows different levels of aggression. For example, they are less hostile towards ''T. melanocephalum'' in contrast to ''P. fervida''. Mortality rates in ''T. melanocephalum'' and ''P. fervida'' when fighting with red imported fire ants are high, being 31.8% and 49.9% respectively. The mortality rate for red imported fire ant workers, however, is only 0.2% to 12%. The imported crazy ant (''Nylanderia fulva'') exhibits greater dominance than the red imported fire ant and has been known to displace them in habitats where they encounter each other in. Larger colonies of pavement ants ('' Tetramorium caespitum)'' can destroy red imported fire ant colonies, leading entomologists to conclude that this conflict between the two species may help impede the spread of the red imported fire ant. Individuals infected by SINV-1 can be killed faster than healthy individuals by '' Monomorium chinense''. This means that ants infected with SINV-1 are weaker than their healthy counterparts and more than likely will be eliminated by ''M. chinense''. However, major workers, whether they are infected or not, are rarely killed.
In areas it is native to, the red imported fire ant is still a dominant species and coexists with 28 ant species in gallery forest
A gallery forest is one formed as a corridor along rivers or wetlands, projecting into landscapes that are otherwise only sparsely treed such as savannas, grasslands, or deserts. The gallery forest maintains a more temperate microclimate above th ...
gaps and ten species in xerophytic
A xerophyte (from Greek ξηρός ''xeros'' 'dry' + φυτόν ''phuton'' 'plant') is a species of plant that has adaptations to survive in an environment with little liquid water, such as a desert such as the Sahara or places in the Alps or t ...
forest grassland, winning most aggressive interactions with other ants. However, some ants can be co-dominant in areas where they coexist such as the Argentine ant, where they compete symmetrically. Workers regularly engage in food competition with other ants, and can suppress the exploitation of food resources from honeydew-producing hemipterans (specifically from ''Phenacoccus solenopsis
''Phenacoccus solenopsis'', the cotton mealybug or solenopsis mealybug, is a species of mealybug in the family Pseudococcidae. Having originated in North America, it has spread to other parts of the world and become a major pest of cotton crops.
...
'') from native ants; however, red imported fire ants are unable to eliminate ''T. melanocephalum'' completely although they consume a higher proportion of food. Instead, the two ants may peacefully coexist and share the honeydew. When encountering neighboring fire ants, workers may take on death-feigning behaviours to avoid them with success. However, such behaviour is only seen in young workers, as older workers either flee or fight back when threatened.
As mentioned, red imported fire ants and Argentine ants compete with each other. Mortality rates vary in different scenarios (i.e. mortality rates in colony confrontation is lower than those confronting each other in the field). Major workers can also withstand more injuries to their bodies, thus increasing the mortality rate of Argentine ants. For an Argentine ant colony to successfully wipe out a monogyne colony of 160,000 workers, the colony would need 396,800 workers. A colony that has reduced in size due to successful bait treatment are prone to predation by Argentine ants. The ants may play a vital role in removing weakened fire ant colonies, and they may also be important in slowing the spread of these fire ants, especially in heavily infested Argentine ant areas. Despite this, Argentine ant populations in the southeastern United States have declined following the introduction of the red imported fire ant.
Mutualism
Red imported fire ants have formed a relationship with an invasive mealybug
Mealybugs are insects in the family Pseudococcidae, unarmored scale insects found in moist, warm habitats. Many species are considered pests as they feed on plant juices of greenhouse plants, house plants and subtropical trees and also act as a ...
, ''Phenacoccus solenopsis''. Colony growth is known to increase if ants have access to resources produced by ''P. solenopsis'', and the population density of these mealybugs is significantly higher in areas where red imported fire ants are present (the spread of ''P. solenopsis'' in areas it is not native is attributed to the presence of the ants). As well as that, the life expectancy and reproductive rate of ''P. solenopsis'' both increase. These mealybugs may even be transported by workers back to their nest. Predation of ''P. solenopsis'' decreases due to tending workers interfering with the predation and parasitism by natural enemies. Mealybugs are preyed on by the lady beetle ('' Menochilus sexmaculatus'') and are hosts of two parasites ('' Aenasius bambawalei'' and ) if there are no ants present, but this is different if ants are present. Lady beetles are less frequently seen on plants with red imported fire ants, and the rate of "mummy" nymphs is significantly lower. This is clearly evident as scientists observed that cotton aphid (''Aphis gossypii
''Aphis gossypii'' is a tiny insect, an aphid ("greenfly") in the superfamily Aphidoidea in the order Hemiptera. It is a true bug and sucks sap from plants. It is a widely distributed pest of a variety of agricultural crops in the families Cucu ...
'') populations, and the predation of sentinel bollworm eggs, increased in areas with red imported fire ant presence. Red imported fire ants have developed a mutual relationship with another mealybug ('' Dysmicoccus morrisoni''). The ants promote the colony growth of ''D. morrisoni'' through protection, covering the colonies up with debris and collecting the honeydew they secrete.
Toxicology
The toxicology of red imported fire ant venom has been relatively well studied. Thevenom
Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a st ...
is important to the ant, enabling it to capture its prey and to defend itself. Some 14 million people are stung annually in the United States, who may suffer reactions ranging from mild eczema
Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved c ...
to anaphylactic shock
Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the follow ...
. Most common reactions to fire ant stings are a burning sensation at the sting site, followed by urticaria
Hives, also known as urticaria, is a kind of skin rash with red, raised, itchy bumps. Hives may burn or sting. The patches of rash may appear on different body parts, with variable duration from minutes to days, and does not leave any long-last ...
and pustule formation. Some victims may develop a more serious allergic reaction which can be life-threatening.
The venom is mainly composed of insoluble alkaloids with a minor watery phase containing some 46 proteins of which four are reported as allergen
An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies.
In technical t ...
s. Effective immunotherapy is available.
Relationship with humans
As pests
Because of their notoriety and invasive behaviour, red imported fire ants are considered pests
PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
. In the United States, the Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
estimates more than $5 billion is spent annually on medical treatment, damage, and control in infested areas. In Texas alone, red imported fire ants caused $300 million in damages for livestock, wildlife and public health. Approximately $36 per American household, and more than $250 million has been spent to control and eradicate red imported fire ants. Private agencies spend $25 to $40 million on pesticides annually. Unsuccessful eradication in Australia may cost the economy billions in damages annually and, based on a Queensland government study, the estimated cost could reach $43 billion over 30 years.
Red imported fire ants thrive in urban areas, especially in backyards, golf courses, parks, recreational areas, school grounds, and street verges, in which their presence may deter outdoor activities. If they enter homes or properties, they can harm pets if they are caged, penned, tied or cannot escape. Nests can be built under pavements or even roads, as well as under driveways, foundations, lawns, edges of sidewalks, under patio slabs, in electrical boxes or near power lines. A colony can excavate huge quantities of soil, resulting in structural problems in driveways, pavings and walls, and can also cause the formation of potholes in roads. Additional damage by mounds can be inflicted on trees, yard plants, and pipes; some structures may also collapse. Colonies may migrate into human homes after heavy rain to take refuge from saturated soil.
Not only do they thrive in urban areas, red imported fire ants can damage equipment and infrastructure and impact business, land, and property values. They are also attracted to electricity; electrically stimulated workers release venom alkaloids, alarm pheromones, and recruitment pheromones, which in return attracts more workers to the site. As a result, red imported fire ants can destroy electrical equipment. This is known as magnetism
Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles ...
, where scientists have identified internal magnetic materials which may play a role in orientation behaviours. They are known to chew through electrical insulation which causes damage to electric motors, irrigation lines, pumps, signal boxes, transformers, telephone exchanges, and other equipment. Colonies aggregate near electrical fields and are capable of causing short circuits or interfering with switches and equipment such as air conditioners, computers, and water pumps. They are also known to infest airport landing areas and traffic lights.
In 2002, the farm gate value of decorative producing nurseries in Orange, Los Angeles, and San Diego counties was $1.3 billion. According to author Les Greenberg of the Center for Invasive Species Research, roughly 40% of crops are produced in these three counties, making it one of the major crops in these areas. “The value of California's entire nursery industry in 2002 was estimated at $2.6 billion” (Greenberg, 1). This business is already feeling the effects of quarantine laws that need pesticide soaking before imports can begin. Immediate costs include the spraying of insecticides to all plants in restricted zones.
In agriculture
The red imported fire ant is a significant agricultural pest in areas where it is not native. They are capable of damaging crops, and they threaten pastures and orchard
An orchard is an intentional plantation of trees or shrubs that is maintained for food production. Orchards comprise fruit- or nut-producing trees which are generally grown for commercial production. Orchards are also sometimes a feature of ...
s. The mounds themselves can destroy agricultural equipment such as irrigation systems and damage machinery during harvest time. The ants are known to invade soybean crops causing lower yields, and could cause $156 million in losses for soybean crops in the southeastern United States. Reports from Georgia and North Carolina
North Carolina () is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. The state is the List of U.S. states and territories by area, 28th largest and List of states and territories of the United ...
claim that 16.8 to 49.1 kg/ha of soybeans could not be harvested due to interference from fire ant mounds; combine harvesters
The modern combine harvester, or simply combine, is a versatile machine designed to efficiently harvest a variety of grain crops. The name derives from its combining four separate harvesting operations— reaping, threshing, gathering, and winn ...
skipped over the mounds preventing the crops from being harvested, and farmers raised the cutter bars on their combine harvesters to avoid impacting the mounds. The feeding behaviour of red imported fire ants can result in significant damage to many other crops, including: beans, cabbage, citrus, corn, cucumber, eggplant, okra
Okra or Okro (, ), ''Abelmoschus esculentus'', known in many English-speaking countries as ladies' fingers or ochro, is a flowering plant in the mallow family. It has edible green seed pods. The geographical origin of okra is disputed, with su ...
, peanut, potato, sorghum
''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many other ...
, sunflower, and sweet potato. The ants also interfere with plants' root systems and feed on young growth. Sometimes, colonies build mounds around or near the base of citrus trees chew off new growth and feed on the flowers or developing fruit. Citrus trees are often girdled or killed.
Despite its pest status and notoriety, the red imported fire ant can be beneficial. The ant is an effective insect predator, so it may serve as a biological agent against other pest species, especially in sugarcane fields. Pest insects the ant kills include: boll weevils (''Anthonomus grandis'') in cotton crops, sugarcane borer
''Diatraea saccharalis'', the sugarcane borer, is a species of moth of the family Crambidae. It was described by Johan Christian Fabricius in 1794. It is native to the Caribbean, Central America, and the warmer parts of South America south to n ...
s (''Diatraea saccharalis'') in sugarcane fields, horn flies (''Haematobia irritans'') in manure, velvetbean caterpillars (''Anticarsia gemmatalis'') in soybeans, and whiteflies that are found in greenhouses. A number of studies indicate that red imported fire ants do not interfere or attack insects of economic importance in cotton fields, which has resulted in many farmers in the southeastern regions of the United States viewing red imported fire ants as beneficial. However, some scientists have suggested that the beneficial status of the red imported fire ant is hard to predict when geography, plant size, season, soil moisture and the use of insecticides are not considered. These factors may lower the efficacy of red imported fire ants as pest control agents. Another factor is that workers are indiscriminate and kill beneficial insects such as predators that eat horn flies and other pests in pastures and predators of aphids and scale insects. They also reduce the efficacy of parasitic wasps against pest species by eating the larvae and pupae.
Control
In comparison to other ant species like ''Anoplolepis gracilipes
''Anoplolepis'', also known as the "pugnacious ants", is a genus of ants in the subfamily Formicinae and tribe Lasiini. The genus is mainly found in the Afrotropics
The Afrotropical realm is one of Earth's eight biogeographic realms. It i ...
'', which rapidly take over areas they have been contained in, red imported fire ants are fairly easy to control. The first proposals to controlling the ant occurred in 1957 when the United States Congress
The United States Congress is the legislature of the federal government of the United States. It is Bicameralism, bicameral, composed of a lower body, the United States House of Representatives, House of Representatives, and an upper body, ...
authorised an eradication program using federal and state funding. Research on the ant and its biology has been continuous after the establishment of an eradication program, and many chemicals were used to eliminate them. However, scientists discovered that these insecticides were killing native fauna, and the Environmental Protection Agency
A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale ...
subsequently outlawed them. Some scientists even questioned whether the ants were pests or not. Today, it is unlikely that the red imported fire ant will be eradicated in areas such as the United States. Populations can be managed properly if an integrated approach is used. Some scientists have considered using the ants' natural enemies against it; this includes ''Kneallhazia solenopsae
''Kneallhazia solenopsae'' is a unique pathogenic intracellular microsporidium, that infects two of the fire ant species: the red ''Solenopsis invicta'' and the black '' Solenopsis richteri'' in North and South America.
''Kneallhazia solenopsae' ...
'' and '' B. bassiana''. Phorid flies have also been viewed as potential biological agents, as they can reduce foraging activity in red imported fire ants and affect population levels. However, they are unable to affect colony growth rate. In addition, parasitic ants, parasitic wasps, mites, other pathogens, nematodes, and fungi have been considered to be potential biological agents. Others suggest that populations can be maintained or reduced by manipulating several ecological factors.
Several baits have been used to control populations. Mounds are destroyed in a matter of weeks if baits are used on them. Baits are considered to be effective and simple to use against red imported fire ants, in comparison to drenching, dusting, or fumigating. They are sprinkled onto the mound then the ants take and consume them. Certain baits such as growth regulator baits, and boric acid-sucrose water baits, benefit native fauna and low concentrations are usually required to kill a colony. Others baits used against red imported fire ants include Amdro, Ascend, hydramethylnon
Hydramethylnon is an organofluorine compound. It is also known as AC 217,300. It is in a chemical class called trifluoromethyl aminohydrazone, which is a metabolic inhibitor. It is classified as a pesticide designed to control insects that are ...
, and Maxforce.
Solid and liquid bait insecticides, if improperly applied in a location, may be moved through waterflow in to unintended water sources. Often, this happens through non-point sources including many diffuse sources. As snow melts and rainfall moves over and through the ground, the water picks up improperly applied insecticides and deposits them in to larger bodies of water, rivers, wetlands, or percolates in to watersheds.
Researchers have also been experimenting with other methods, such as fumigation, injecting the mound, mound drenching, and surface dusting. Mound drenching entails pouring large volumes of toxic liquid into the mound. While this may affect a large portion of the mound, it is possible it may not reach the queen, thus preventing the destruction of the colony. Surface dusting is similar to mound drenching, except insecticides are applied on top of the mound and soak into the soil when wet. Mound injections use pressurising and injecting insecticides into the mound, but the queen may not be affected by this. Mounds can be eliminated effectively through fumigation. Broadcast treatment is sometimes used by spraying infected areas with agricultural equipment. Finally, spot treatment with insecticides can be used by drilling and injecting the mound with residual insecticide.
Aside from chemical control, other methods that can be employed against these ants include mechanical and electrical devices. However, it is unknown whether or not these devices are effective. Ant-proofing can be effective against colonies nesting inside buildings by caulking and sealing cracks, which successfully suppresses the population outside the walls. Homeowners have used their own methods to remove mounds by pouring boiling water on them or igniting them with flammable liquids. Although these methods may be effective, they are not recommended because they can be harmful to humans and the environment.
Notes
References
Footnotes
Bibliography
* * * * * * *External links
Website
Books and journals about the red imported fire ant
at
Biodiversity Heritage Library
The Biodiversity Heritage Library (BHL) is the world’s largest open access digital library for biodiversity literature and archives. BHL operates as worldwide consortiumof natural history, botanical, research, and national libraries working toge ...
Books and journals about the red imported fire ant
at
Internet Archive
The Internet Archive is an American digital library with the stated mission of "universal access to all knowledge". It provides free public access to collections of digitized materials, including websites, software applications/games, music, ...
National Red Imported Fire Ant Eradication Program
– Queensland Department of Agriculture and Fisheries
Imported Fire Ants
– United States Department of Agriculture
''Solenopsis invicta'' at the AntWiki – Bringing Ants to the World
– Hymenoptera Genome Database project
Species Profile - Red Imported Fire Ant (''Solenopsis invicta'')
National Invasive Species Information Center,
United States National Agricultural Library
The United States National Agricultural Library (NAL) is one of the world's largest agricultural research libraries, and serves as a national library of the United States and as the library of the United States Department of Agriculture. Located ...
.
Media
Footage of phorid flies parasitising fire ants
– Captured by BBC, published by the University of Texas at Austin College of Natural Sciences
Red Fire Ants
– published by National Geographic at YouTube
Casting a Fire Ant Colony with Molten Aluminum
at YouTube
News coverage
– ''The Washington Post'', 2011 {{DEFAULTSORT:Red Imported Fire Ant Solenopsis (ant) Hymenoptera of Asia Hymenoptera of Australia Hymenoptera of North America Hymenoptera of South America Insects described in 1916 Insects described in 1972 Scavengers Agricultural pest insects Biological pest control insects Insects used as insect pest control agents Pest insects Household pest insects