Solenopsis saevissima

The scientific name for Solenopsis saevissima comes from the , which means pipe or channel, opsis, which means appearance or sight 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==

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. Similarly to other species within Solenopsis, it has a conspicuous central hair on the front of its clypeus that extends beyond the outer margin of mandibles. Differently from most other species in the group, it lacks a well-developed medial clypeal tooth and its propodeum is rounded. Proper morphological identification of the species is complicated by interspecies breeding in its native range. Currently it is believed that nominal S. saevissima actually comprises at least 5 cryptic species (i.e. of identical morphology) that can be separated using chemical characters. ==Colony==

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 fertile 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 Hymenoptera, 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-sacrifice. 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. {{cite journal |author1=Pitts, James |title= A Cladistic Analysis of the Solenopsis saevissima Species-group (Hymenoptera:Formicidae)|date=February 2002 |doi=10.1172/JCI16567 | url = https://getd.libs.uga.edu/pdfs/pitts_james_p_200205_phd.pdf {{cite journal |author1=Strassmann, Joan |author2=Queller, David |title= Insect societies as divided organisms: The complexities of purpose and cross-purpose|date=May 2007 ==Behavior==

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. This secreted pheromone attracts and excites the workers, drawing them to the direction indicated by the trail. 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 trails. 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. 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 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 trail for others to follow and similar to the other chemical signals, this odor trail 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. ==Parasitic enemies==

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. S. saevissima is reported to be attacked by more phorids than any other type of fire ants. 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 is ambiguous as to whether it attacks S. saevissima because part of its life is spent being cared for by the ants. ==Habitat and distribution==

Habitat S. saevissima is native to the tropical and warm climate regions of South America, 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. Distribution S. saevissima has been mostly restricted in the eastern half of South America, 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 has not been imported into the United States. ==Sting==

Venom Ants belonging to the genus Solenopsis are known as "fire ants" because of the pain caused by their stings, which inject venoms. The venoms of fire ants are characterized by a variety of alkaloids known as solenopsins (2-methyl-6-alkylpiperidines) that exhibit necrotic, hemolytic, antibiotic, and toxic properties. that can be highly allergenic. The queens of S. saevissima , like in other fire ant species, mainly produce the alkaloid compound isosolenopsin A (cis-2methyl-6-undecylpiperidine) while the workers mainly produce trans-2methyl-6-undecylpiperidine. 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 anaphylaxis which can lead to death. First aid includes external treatments of topical steroid 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 is because it encompasses a number of highly similar species which were once all considered under the name "Solenopsis saevissima". This number of species within this species group currently includes 13 individual species which are included in a group of 20 aggressive species of ants popularly known as fire ants. 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 that 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: • Solenopsis altipunctata (probably now re-baptized to Solenopsis metallica) • Solenopsis daguerrei (parasitic) • Solenopsis electra • Solenopsis hostilis (parasitic) • Solenopsis interrupta • Solenopsis invicta (invasive) • Solenopsis macdonaghi • Solenopsis megergates • Solenopsis pusillignis • Solenopsis pythia • Solenopsis quinquecuspis • Solenopsis richteri (invasive) • Solenopsis saevissima • Solenopsis weyrauchi ==References==