Solenopsis saevissima
Encyclopedia
Solenopsis saevissima, commonly known in Brazil
as formiga ruiva (red ant), is one of more than 185 species
in the genus Solenopsis. It, along with 12 other species, is also a member of the Solenopsis saevissima species-group.
Although it’s indigenous to South America
, it has been imported to Africa
and the Galápagos Islands
. Currently, there is no evidence of it in the United States
. S. saevissima is known for its powerful and painful sting, hence the name ‘fire ant
.’ It is a pest in horticulture
and the current method of control is to introduce the scuttle fly phorid into its habitat
. No further information about S. saevissima and its behaviors is known or studied except in Brazil
.
: Solen, which means pipe or channel, opsis, which means appearance or sight and saevissima, which means “the very cruel.” S. saevissima is named so because it is known to be even more vicious than S. invicta, the red imported fire ants, which costs the United States millions of dollars per year in agricultural, medical, and traffic-related damage.
S. saevissima belongs to the Solenopsis saevissima species-group which includes 13 fire ant species that exhibit remarkably similar morphology
, rendering morphological distinction nearly impossible. S. saevissima has polymorphic
adult workers that differ in size depending on their castes: minor workers are generally smaller and major workers are relatively larger. The major workers also typically have trapezoidal heads and antennal scapes almost reaching their vertex
; the minor workers have ovate heads and antennal scapes that extend past their heads.
Like all species of the S. saevissima species-group, S. saevissima has workers averaging 1.9 mm in length, antennae
containing 10 segments, and mandibles with 4 or 5 teeth. Unlike the other species, it has only one central hair on the front of its clypeus
and its propodeum
is rounded. Further identification of the species is complicated by interspecies breeding.
female: the queen and the workers are aggressive towards other colonies. The stable inhabitants of the nest, similar to those of the other fire ants, include one reproductive queen and hundreds to thousands of sterile daughter workers. Occasionally, the nest would be inhabited by a few virgin queens and several drones (male ants). The virgin queens must soon leave the nest to establish their own colonies and the drones only live long enough for the mating flight and then they die afterwards. The job of the queen is to reproduce; the job of the drones is to pass on their genes through mating with the queen; and the jobs of the workers are to build, repair, and protect the nest, to care for the brood, and to feed everyone.
, is eusocial: an extreme form of kin selection
in which members of a group willingly give up their reproductive abilities in favor of the reproductive success of their close relatives. For S. saevissima, the workers are all sterile female daughters who dedicate their lives to the caring and protection of their future sisters: the broods of the fertile queen (their mother). In eusociality, the sterile ants often perform specialized tasks to effectively care for the reproductive queen, including group defense and self-sacrifices.
Small and middle-sized workers generally forage alone in paths of irregular loops when away from the colony. If they find a small, single food source, they will attempt to drag it back to the nest. However, if the food source is too large or is in several components, the worker will first inspect it for 10 to 30 seconds, feed itself, and then secrete a trail substance by the Dufour’s gland to recruit fellow workers.
This secreted pheromone attracts and excites the workers, drawing them to the direction indicated by the trail. The trail consists of fragments of secretion and is extremely specific to each species. Intrinsically, the secretion itself reveals neither the quantity of the food nor the quality. The quantity of food is described by the number of ants in the mass forage since the larger the quantity of food, the more ants will be attracted. However the number of workers in the mass forage does stabilize at a certain level because those who are unable to reach the food leave without laying any trials. The quality of the food is communicated through percentage of positive responses: workers can choose whether or not to secrete trail substances depending on their preference of the food. The more scrumptious the food, the more trails. However, if the food is beyond the radius of 5 to 10 centimeters from the colony, the workers will abandon the trail and turn around. The longer a worker is away from the colony, the less likely that he will return.
S. saevissima has an extremely rapid proliferation rate. In less than one year’s time, a single queen can mother several thousands of workers, males, and new virgin queens.
Apodicrania termophila, a species of phorid fly, attacks certain South American fire ants, although it’s ambiguous as to whether it attacks S. saevissima because part of its life is spent cared by the ants.
, especially eastern Brazil
(Pelotas
). It is commonly found in the disturbed areas of grasslands and forest
openings due to its workers’ nature as excellent recolonizers. These disturbed sites can be manmade (farms or plantation) or natural (animal trails and riverbanks).
S. saevissima prefers to build its colonies in sandy soil rather than clays. Mounds can reach up to 10 feet in length and have over one million residents.
, with rare imports to Africa
and the Galápagos Islands
. It was reported in Guinea
in the 1920s and Kenya
in 1911, but there has been no recent collections. So far, it hasn’t been imported into the United States
.
Solenopsis
are known as “fire ants” because of the potency of their venoms. The venoms are characterized by a variety of 2-methyl-6-alkylpiperidines mixtures and exhibit necrotic, hemolytic, antibiotic
, and toxic properties. The queens of S. saevissima mainly produce cis-2methyl-6-undecylpiperidine, while the workers mainly produce trans-2methyl-6-undecylpiperidine. This shows that the assortment of alkaloid
production is specific to each caste
and therefore suggests that the recognition of the various configuration of alkaloid venom may be important for distinguishing the castes.
which can lead to death. First aid includes external treatments of topical steroid
cream and oral medicines of antihistamines.
The majority of the species within this group are “thief ants” with small monomorphic workers. They tend to build their colonies near those of other ant species, so they can steal their food. The rest of the species are “fire ants,” including the species S. saevissima. These have larger polymorphic workers and forage for their own food.
The species group currently comprises thirteen species:
. He along with Bert Hölldobler
, is the co-author of The Ants
, which is referenced in this article. Many of his other journal articles are also referenced here.
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
as formiga ruiva (red ant), is one of more than 185 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in the genus Solenopsis. It, along with 12 other species, is also a member of the Solenopsis saevissima species-group.
Although it’s indigenous to South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, it has been imported to Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and the Galápagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
. Currently, there is no evidence of it in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. S. saevissima is known for its powerful and painful sting, hence the name ‘fire ant
Fire ant
Fire ants are a variety of stinging ants with over 285 species worldwide. They have several common names, including ginger ants, tropical fire ants and red ants.- Appearance :...
.’ It is a pest in horticulture
Horticulture
Horticulture is the industry and science of plant cultivation including the process of preparing soil for the planting of seeds, tubers, or cuttings. Horticulturists work and conduct research in the disciplines of plant propagation and cultivation, crop production, plant breeding and genetic...
and the current method of control is to introduce the scuttle fly phorid into its habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
. No further information about S. saevissima and its behaviors is known or studied except in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
.
Etymology
The scientific name for Solenopsis saevissima comes from the GreekGreek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
: Solen, which means pipe or channel, opsis, which means appearance or sight and saevissima, which means “the very cruel.” S. saevissima is named so because it is known to be even more vicious than S. invicta, the red imported fire ants, which costs the United States millions of dollars per year in agricultural, medical, and traffic-related damage.
Morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
, rendering morphological distinction nearly impossible. S. saevissima has polymorphic
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...
adult workers that differ in size depending on their castes: minor workers are generally smaller and major workers are relatively larger. The major workers also typically have trapezoidal heads and antennal scapes almost reaching their vertex
Vertex
Vertex may refer to:-Mathematics:*Vertex , an angle point of any shape or angle*Vertex , a node in a graph*Vertex , a local extreme point of curvature...
; the minor workers have ovate heads and antennal scapes that extend past their heads.
Like all species of the S. saevissima species-group, S. saevissima has workers averaging 1.9 mm in length, antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
containing 10 segments, and mandibles with 4 or 5 teeth. Unlike the other species, it has only one central hair on the front of its clypeus
Clypeus
The clypeus is one of the sclerites that makes up the "face" of an arthropod.In insects, the clypeus delimits the lower margin of the face, with the labrum articulated along the ventral margin of the clypeus. The mandibles bracket the labrum, but do not touch the clypeus. The dorsal margin of the...
and its propodeum
Propodeum
The propodeum is the first abdominal segment in Apocrita Hymenoptera . It is fused with the thorax to form the mesosoma. It is a single large sclerite, not subdivided, and bears a pair of spiracles. It is strongly constricted posteriorly to form the articulation of the petiole, and gives apocritans...
is rounded. Further identification of the species is complicated by interspecies breeding.
Social Hierarchy
Unlike S. invicta, which has been identified as unicolonial ants (polygynous colonies coalescing into one giant supercolony in which there is no aggression between workers of the various colonies), S. saevissima forms monogynous colonies, in which each colony has only one fertileFertile
The term fertile describes a condition whereby organisms are able to produce physically healthy offspring.Fertile may also refer to:...
female: the queen and the workers are aggressive towards other colonies. The stable inhabitants of the nest, similar to those of the other fire ants, include one reproductive queen and hundreds to thousands of sterile daughter workers. Occasionally, the nest would be inhabited by a few virgin queens and several drones (male ants). The virgin queens must soon leave the nest to establish their own colonies and the drones only live long enough for the mating flight and then they die afterwards. The job of the queen is to reproduce; the job of the drones is to pass on their genes through mating with the queen; and the jobs of the workers are to build, repair, and protect the nest, to care for the brood, and to feed everyone.
Eusociality
S.saevissima, similar to the other social insects in the order HymenopteraHymenoptera
Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
, is eusocial: an extreme form of kin selection
Kin selection
Kin selection refers to apparent strategies in evolution that favor the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction. Charles Darwin was the first to discuss the concept of group/kin selection...
in which members of a group willingly give up their reproductive abilities in favor of the reproductive success of their close relatives. For S. saevissima, the workers are all sterile female daughters who dedicate their lives to the caring and protection of their future sisters: the broods of the fertile queen (their mother). In eusociality, the sterile ants often perform specialized tasks to effectively care for the reproductive queen, including group defense and self-sacrifices.
Haplodiploidy and Hamilton's Rule
All Solenopsis species has the haplodiploid sex-determination system, in which the females are developed from the merging of a sperm and an egg and the males are developed from an unfertilized egg. Ideally, according to Hamilton’s rule, the female workers would all share the same father and therefore receive the same X chromosome from him and then receive one of the two possible X chromosomes from their mother, which should result in ¾ relatedness. However, because it is unknown as to whether the S. saevissima queen mates with only one single drone or multiple drones, one can only assume that the sister workers are related to each other and the immature broods by 50% - 75%. This is still closer than the 50% relatedness the workers would have had with their own daughters. Then it’s no surprise that the eusocial workers do give up their reproductive ability to take care of their sisters because, mathematically, they are able to pass on more of their genes in this method. But of course they are only related to their brothers by ¼, so haplodiploidy alone does not explain the origin of eusociality.Foraging
S. saevissima often displaces the other ant species within the vicinity of its nest because it is omnivorous and opportunistic and prefers abundant food supplies, therefore reducing the resources for others. Its typical diet includes sugary juices from dead beetles, isopods, and plants.Small and middle-sized workers generally forage alone in paths of irregular loops when away from the colony. If they find a small, single food source, they will attempt to drag it back to the nest. However, if the food source is too large or is in several components, the worker will first inspect it for 10 to 30 seconds, feed itself, and then secrete a trail substance by the Dufour’s gland to recruit fellow workers.
This secreted pheromone attracts and excites the workers, drawing them to the direction indicated by the trail. The trail consists of fragments of secretion and is extremely specific to each species. Intrinsically, the secretion itself reveals neither the quantity of the food nor the quality. The quantity of food is described by the number of ants in the mass forage since the larger the quantity of food, the more ants will be attracted. However the number of workers in the mass forage does stabilize at a certain level because those who are unable to reach the food leave without laying any trials. The quality of the food is communicated through percentage of positive responses: workers can choose whether or not to secrete trail substances depending on their preference of the food. The more scrumptious the food, the more trails. However, if the food is beyond the radius of 5 to 10 centimeters from the colony, the workers will abandon the trail and turn around. The longer a worker is away from the colony, the less likely that he will return.
Mating
Mating flights between the winged queen and winged drones usually occur between the late mornings to midafternoons. This typically takes place on days following a rainy day or night. The mating ritual is similar to that of the average fire ants: the queens only mate once in their lifetime, storing the sperms inside their bodies, and the males soon die afterward. The virgin queens and drones of several adjacent colonies gather together for the flight and interbreed. No intra-colony breeding occurs. Since only monogynous colonies have been reported for this species, a new queen would need to leave her the colony of her birth and establish her own colony.S. saevissima has an extremely rapid proliferation rate. In less than one year’s time, a single queen can mother several thousands of workers, males, and new virgin queens.
Brood Caring
Studies have shown that the immature forms of worker ants secrete pheromones that induce adult workers to recognize and care for them. In one experiment, adult workers were observed to carry grits coated with a special chemical extract into the nest. Once inside, the ants groomed the treated grits and generally proceeded as if caring for their own broods. When the colony is disturbed, workers are seen to pick up the treated grits and run with them in the same manner as they would have with their broods.Alarm Call
When in any sense of danger, the workers release pheromones as a type of alarm call to warn their sisters. Most alarm pheromones are volatile compounds that function as attractants. Sometimes, odor trail pheromone is also secreted by the stressed ant. This then provides the sister workers with a directional guide.Flooding
Sometimes, due to heavy rainfall in South America, floods occur. When the water rises, S. saevissima all move upward, from the underground tunnels to the top of the nest. The workers then form large masses that can float on water, with the queen and the broods protected in the center. The large mass of workers eventually anchors to either a grass stem or a bush. When the flood recedes, they all return to soil and build a new nest.Emigration
Colony emigration for S. saevissima occurs in a similar manner to mass foraging: communication through chemical signals. The workers emit an odor trial for others to follow and similar to the other chemical signals, this odor trial is also specific to each species. Migration can be caused by unexpected environmental factors such as flooding or establishment of new colonies by new queens.Ants
S. saevissima is said to be a host species for the parasitic ant species, S. hostilis, although no extensive studies have seen conducted in this host-parasite relationship. Also, S. hostilis has not been collected since its characterization in 1959.Phorids
At least 17 species of phorids are known to parasitize the workers of the S. saevissima species-group. S. saevissima is reported to be attacked by more phorids than any other type of fire ants. The adult female phorid flies inject their eggs into the thorax of the workers. Then, the maggots decapitate the heads of the ants and eat away their brain. Phorids are especially likely to parasitize workers either during the mating flights of the queen or stalking them during forage. In defense to phorids, fire ants evolved underground foraging tunnels.Apodicrania termophila, a species of phorid fly, attacks certain South American fire ants, although it’s ambiguous as to whether it attacks S. saevissima because part of its life is spent cared by the ants.
Habitat
S. saevissima is native to the tropical and warm climate regions of South AmericaSouth America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, especially eastern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
(Pelotas
Pelotas
Pelotas is a Brazilian city and municipality , the third most populous in the southern state of Rio Grande do Sul. Pelotas is located 270 km from Porto Alegre, the capital city of the state, and 130 km from the Uruguayan border...
). It is commonly found in the disturbed areas of grasslands and forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
openings due to its workers’ nature as excellent recolonizers. These disturbed sites can be manmade (farms or plantation) or natural (animal trails and riverbanks).
S. saevissima prefers to build its colonies in sandy soil rather than clays. Mounds can reach up to 10 feet in length and have over one million residents.
Distribution
S. saevissima has been mostly restricted in the eastern half of South AmericaSouth America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, with rare imports to Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and the Galápagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
. It was reported in Guinea
Guinea
Guinea , officially the Republic of Guinea , is a country in West Africa. Formerly known as French Guinea , it is today sometimes called Guinea-Conakry to distinguish it from its neighbour Guinea-Bissau. Guinea is divided into eight administrative regions and subdivided into thirty-three prefectures...
in the 1920s and Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...
in 1911, but there has been no recent collections. So far, it hasn’t been imported into the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
Venom
Ants belonging to the genusGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Solenopsis
Solenopsis
Solenopsis is a scientific name for two genera:* Solenopsis , a genus of ants* Solenopsis , a genus of flowering plants in the family Campanulaceae, commonly treated as a synonym of Laurentia, or Isotoma...
are known as “fire ants” because of the potency of their venoms. The venoms are characterized by a variety of 2-methyl-6-alkylpiperidines mixtures and exhibit necrotic, hemolytic, antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
, and toxic properties. The queens of S. saevissima mainly produce cis-2methyl-6-undecylpiperidine, while the workers mainly produce trans-2methyl-6-undecylpiperidine. This shows that the assortment of alkaloid
Alkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...
production is specific to each caste
Caste
Caste is an elaborate and complex social system that combines elements of endogamy, occupation, culture, social class, tribal affiliation and political power. It should not be confused with race or social class, e.g. members of different castes in one society may belong to the same race, as in India...
and therefore suggests that the recognition of the various configuration of alkaloid venom may be important for distinguishing the castes.
Treatment
Venom from the bite of a sterile female fire ant typically causes painful red bumps with white pustules on the skin of its victim. It may also cause severe allergic reactions such as anaphylaxisAnaphylaxis
Anaphylaxis is defined as "a serious allergic reaction that is rapid in onset and may cause death". It typically results in a number of symptoms including throat swelling, an itchy rash, and low blood pressure...
which can lead to death. First aid includes external treatments of topical steroid
Topical steroid
Topical steroids are the topical forms of corticosteroids. Topical steroids are the most commonly prescribed topical medications for the treatment of rash, eczema, and dermatitis. Topical steroids have anti-inflammatory properties, and are classified based on their vasoconstriction abilities. There...
cream and oral medicines of antihistamines.
Species-Group
Solenopsis saevissima is the scientific name for both a species group and the species within that group. This can cause some confusion when reading literary studies about them. This number of species within this species-group is continuously changing as researchers learn more about each individual species.The majority of the species within this group are “thief ants” with small monomorphic workers. They tend to build their colonies near those of other ant species, so they can steal their food. The rest of the species are “fire ants,” including the species S. saevissima. These have larger polymorphic workers and forage for their own food.
The species group currently comprises thirteen species:
- S. altipunctata
- S. daguerrei
- S. electra
- S. hostilis (parasitic)
- S. interrupta
- S. invicta (invasive)
- S. macdonaghi
- S. megergates
- S. pusillignis
- S. pythia
- S. quinquecuspis
- S. richteri (invasive)
- S. saevissima (Current Page)
- S. weyrauchi
Notable People
One notable scientist who has studied S. saevissima is the two-time winner of the Pulitzer Prize for General Non-Fiction Edward O. Wilson. Wilson is known as the “father of sociobiology” and his biological specialty is myrmecologyMyrmecology
Myrmecology is the scientific study of ants, a branch of entomology. Some early myrmecologists considered ant society as the ideal form of society and sought to find solutions to human problems by studying them. Ants continue to be a model of choice for the study of questions on the evolution of...
. He along with Bert Hölldobler
Bert Hölldobler
Bert Hölldobler is a German behavioral biologist and Sociobiologist whose primary study subjects are social insects and in particular ants. He is a co-winner of the Pulitzer Prize for his work on The Ants with Edward O. Wilson...
, is the co-author of The Ants
The Ants
The Ants is a Pulitzer Prize-winning book, written in 1990, by E. O. Wilson and Bert Hölldobler. It was a winner of the Pulitzer Prize for General Non-Fiction in 1991.-Contents:...
, which is referenced in this article. Many of his other journal articles are also referenced here.