Editing Red imported fire ant (section)

==Taxonomy==
[[File:Specimen CASENT0902350 Solenopsis invicta.jpg|thumbnail|left|[[Paratype]] specimen of ''S. invicta'' collected from Brazil]]

The red imported fire ant was first described by Swiss entomologist [[Felix Santschi]] in a 1916 journal article published by ''Physis''.<ref name="Santschi_1916"/> Originally named ''Solenopsis saevissima wagneri'' from a [[syntype]] worker collected from [[Santiago del Estero]], Argentina, Santschi believed the ant was a variant of ''[[Solenopsis saevissima|S. saevissima]]''; the specific epithet, ''wagneri'', derives from the surname of E.R. Wagner, who collected the first specimens.{{sfn|Taber|2000|p=25}} The [[Type (biology)|type]] material is currently housed in [[Natural History Museum of Basel|Naturhistorisches Museum Basel]], Switzerland, but additional type workers are possibly housed in the [[National Museum of Natural History (France)|Muséum national d'histoire naturelle]], Paris.<ref name="Shattuck_et_al_1999">{{cite journal |last1=Shattuck|first1=S.O.|last2=Porter|first2=S.D.|last3=W.|first3=D.P.|date=1999|title=Case 3069. ''Solenopsis invicta'' Buren, 1972 (Insecta, Hymenoptera): proposed conservation of the specific name|journal=Bulletin of Zoological Nomenclature|volume=56|issue=1|pages=27–30|doi=10.5962/bhl.part.23022|issn=0007-5167|doi-access=free}}</ref> In 1930, American [[myrmecology|myrmecologist]] [[William Steel Creighton|William Creighton]] reviewed the genus ''Solenopsis'' and reclassified the taxon as ''Solenopsis saevissima electra wagneri'' at [[wikt:infrasubspecific|infrasubspecific]] rank, noting that he could not collect any workers that referred to Santschi's original description.<ref>{{cite journal|last1=Creighton |first1=W.S. |title=The new world species of the genus ''Solenopsis'' (Hymenop. Formicidae) |journal=Proceedings of the American Academy of Arts and Sciences |date=1930 |volume=66 |issue=2 |pages=39–152 |doi=10.2307/20026320 |jstor=20026320 |url=http://antbase.org/ants/publications/6214/6214.pdf |url-status=dead |archive-url=https://web.archive.org/web/20160304022540/http://antbase.org/ants/publications/6214/6214.pdf |archive-date= 4 March 2016 }}</ref> 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''.<ref>{{cite journal|last1=Wilson|first1=E.O.|title=The ''Solenopsis saevissima'' complex in South America (Hymenoptera: Formicidae)|journal=Memórias do Instituto Oswaldo Cruz|date=1952|volume=50|pages=60–68|doi=10.1590/S0074-02761952000100003|pmid=13012835|issn=0074-0276|doi-access=free}}</ref> 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.<ref>{{cite journal|last1=Ettershank|first1=G.|title=A generic revision of the world Myrmicinae related to ''Solenopsis'' and ''Pheidologeton'' (Hymenoptera : Formicidae)|journal=Australian Journal of Zoology|date=1966|volume=14|issue=1|pages=73–171|doi=10.1071/ZO9660073}}</ref><ref>{{cite journal|last1=Kempf|first1=W.W.|title=Catalogo abreviado das formigas da Regiao Neotropical|journal=Studia Entomologica |series=New Series|date=1972|volume=15|pages=3–344}}</ref>

In 1972, American entomologist William Buren described what he thought was a new species, naming it ''Solenopsis invicta''.<ref name="Buren_1972"/> Buren collected a [[holotype]] worker from [[Cuiabá]] in [[Mato Grosso]], 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 {{sic|invica}} 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.<ref name="Trager_1991">{{cite journal|last1=Trager|first1=J.C.|title=A revision of the fire ants, ''Solenopsis geminata'' group (Hymenoptera: Formicidae: Myrmicinae)|journal=Journal of the New York Entomological Society|date=1991|volume=99|issue=2|pages=141–198|doi=10.5281/zenodo.24912|jstor=25009890}}</ref> The type material is currently housed in the [[National Museum of Natural History]], Washington, D.C.<ref name="Buren_1972"/>

[[File:Specimen CASENT0902350 Solenopsis invicta label.jpg|thumbnail|Casent label of ''S. invicta'' paratype worker]]

In a 1991 review of the species complex, American entomologist James Trager [[Synonym (taxonomy)|synonymised]] ''S. saevissima electra wagneri'' and ''S. wagneri'' together.<ref name="Trager_1991"/> 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 [[Principle of Priority|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]]''.<ref name="Trager_1991"/> In 1995, English [[Myrmecology|myrmecologist]] [[Barry Bolton]] corrected Trager's error, recognising ''S. wagneri'' as the valid name and synonymised ''S. invicta''.<ref name="Bolton_1995">{{cite book|last1=Bolton|first1=B.|isbn=978-0-674-61514-4|title=A New General Catalogue of the Ants of the World|publisher=Harvard University Press|location=Cambridge|year=1995|pages=388–391}}</ref> 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''.<ref name="Bolton_1995"/>{{sfn|Taber|2000|p=26}}

In 1999, Steve Shattuck and colleagues proposed conserving the name ''S. invicta''.<ref name="Shattuck_et_al_1999"/> 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]] (ICZN) use [[plenary power]]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.<ref name="Shattuck_et_al_1999"/> Upon review, the proposal was voted on by the entomological community and was supported by all but two voters. 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.<ref>{{cite journal|author1=International Commission on Zoological Nomenclature|title=Opinion 1976 ''Solenopsis invicta'' Buren, 1972 (Insecta, Hymenoptera): specific name conserved|journal=Bulletin of Zoological Nomenclature|date=2001|volume=58|issue=2|pages=156–157|url=https://archive.org/details/biostor-80718|issn=0007-5167}}</ref> Under the present classification, the red imported fire ant is a member of the genus ''Solenopsis'' in the tribe [[Solenopsidini]], subfamily [[Myrmicinae]]. It is a member of the family [[Formicidae]], belonging to the order [[Hymenoptera]], an order of insects containing ants, [[bee]]s, and [[wasp]]s.<ref>{{AntCat|447760|''Solenopsis invicta''|2016|accessdate=19 August 2016}}</ref>

{{multiple image
| align     = right
| direction = horizontal
| image1    = Solenopsis_invicta_casent0005804_head_1.jpg
| width1    = 208
| image2    = Solenopsis richteri casent0103101 head 1.jpg
| footer = Heads of ''S. invicta'' (left) and ''S. richteri'' (right). Both ants are similar to each other morphologically and genetically. 
}}

===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 (biology)|Polymorphism]] occurs in all species and the [[Mandible (insect mouthpart)|mandible]]s bear four teeth.<ref name="Buren_1972"/> The following [[cladogram]] shows the position of the red imported fire ant among other members of the ''S. saevissima'' species-group:{{refn|Although ''S. geminata'' appears in the cladogram, it is not a member of the species-group. It is only included to serve as an "attachment point"; to be precise, it is showing where the cladogram under investigation connects with the [[Tree of life (biology)|tree of life]].{{sfn|Tschinkel|2006|p=14}}|group = lower-alpha}}{{sfn|Tschinkel|2006|p=14}}

{{clade| style=font-size:100%; line-height:100%
|label1=''[[Fire ant|Solenopsis]]''
|1={{clade
 |1=''[[Solenopsis geminata]]''
 |2={{clade
  |1=''[[Solenopsis daguerrei]]''
  |2={{clade
   |1={{clade
    |1=''[[Solenopsis quinquecupsis]]''
    |2=''[[Solenopsis macdonaghi]]'' }}
   |2={{clade
    |1=''[[Solenopsis megergates]]''
    |2={{clade
     |1='''''Solenopsis invicta'''''
     |2={{clade
      |1=''[[Solenopsis richteri]]''
      |2={{clade
       |1=''[[Solenopsis interrupta]]''
       |2={{clade
        |1=''[[Solenopsis altipunctata]]''
        |2=''[[Solenopsis weyrauchi]]'' }}
       |3={{clade
        |1=''[[Solenopsis saevissima]]''
        |2=''[[Solenopsis pythia]]''
        |3={{clade
         |1=''[[Solenopsis electra]]''
         |2=''[[Solenopsis pusillignis]]'' }} }} }} }} }} }} }} }} }} }}

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.<ref name="Ross_et_al_1987">{{cite journal|last1=Ross|first1=K.G.|last2=Meer|first2=R.K.V.|last3=Fletcher|first3=D.J.C.|last4=Vargo|first4=E.L.|title=Biochemical phenotypic and genetic studies of two introduced fire ants and their hybrid (Hymenoptera: Formicidae)|url=https://archive.org/details/sim_evolution_1987-03_41_2/page/280|journal=Evolution|date=1987|volume=41|issue=2|pages=280–293|doi=10.2307/2409138|jstor=2409138|pmid=28568766}}</ref><ref>{{cite journal|last1=Ross|first1=K.G.|last2=Vargo|first2=E.L.|last3=Fletcher|first3=David J.C.|title=Comparative biochemical genetics of three fire ant species in North America, with special reference to the two social forms of ''Solenopsis invicta'' (Hymenoptera: Formicidae)|url=https://archive.org/details/sim_evolution_1987-09_41_5/page/979|journal=Evolution|date=1987|volume=41|issue=5|pages=979–990|doi=10.2307/2409186|pmid=28563420|jstor=2409186}}</ref>{{sfn|Tschinkel|2006|p=15–16}}<ref name="Pitts_et_al_2005">{{cite journal|last1=Pitts|first1=J.P.|last2=McHugh|first2=J.V.|last3=Ross|first3=K.G.|title=Cladistic analysis of the fire ants of the ''Solenopsis saevissima'' species-group (Hymenoptera: Formicidae)|journal=Zoologica Scripta|date=2005|volume=34|issue=5|pages=493–505|doi=10.1111/j.1463-6409.2005.00203.x|s2cid=85792334}}</ref> [[Hybrid (biology)|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|date=May 2024}}, when they first encountered each other in southern [[Alabama]].<ref name="Ross_et_al_1987"/>{{sfn|Tschinkel|2006|p=503}} Based on [[mitochondrial DNA]], examined [[haplotype]]s do not form a [[Monophyly|monophyletic]] [[clade]]. Some of the examined haplotypes form a closer relationship to ''[[Solenopsis megergates|S. megergates]]'', ''S. quinquecuspis'' and ''S. richteri'' than they do with other ''S. invicta'' haplotypes. The occurrence of a possible [[Paraphyly|paraphyletic]] 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.<ref name="Pitts_et_al_2005"/><ref>{{cite thesis|type=Ph.D.|last=Pitts|first=J.P.|date=2002|title=A cladistic analysis of the Solenopsis saevissima species-group (Hymenoptera: Formicidae)|publisher=University of Georgia, Athens|url=https://getd.libs.uga.edu/pdfs/pitts_james_p_200205_phd.pdf|pages=42–43}}</ref>

===Genetics===
Studies show that [[mitochondrial DNA]] variation occurs substantially in [[Gyne|polygyne]] societies (nests with multiple queens),{{sfn|Taber|2000|p=43}} but no variation is detected in [[Gyne|monogyne]] societies (nests with a single queen).<ref>{{cite journal |last1=Ross |first1=K.G. |last2= Shoemaker |first2=D.D. |title= Nuclear and mitochondrial genetic structure in two social forms of the fire ant ''Solenopsis invicta'': insights into transitions to an alternate social organization |url=https://archive.org/details/sim_heredity_1997-06_78_6/page/590 |journal= Heredity |date=1997 |volume=78 |issue=6 |pages= 590–602 |doi= 10.1038/hdy.1997.98|s2cid=19225329 |doi-access=free |bibcode=1997Hered..78..590R }}</ref> [[Triploid syndrome|Triploidy]] (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.<ref>{{cite journal|last1=Krieger|first1=M.J.B.|last2=Ross|first2=K.G.|last3=Chang|first3=C..W.Y.|last4=Keller|first4=L.|title=Frequency and origin of triploidy in the fire ant ''Solenopsis invicta'' |url=https://archive.org/details/sim_heredity_1999-02_82_2/page/142|journal= Heredity |date=1999 |volume=82 |issue=2 |pages=142–150 |doi= 10.1038/sj.hdy.6884600|s2cid=13144037|doi-access=free|bibcode=1999Hered..82..142K }}</ref> The red imported fire ant is the first species shown to possess a [[green-beard effect|green-beard gene]], by which natural selection can favour [[Altruism (biology)|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.<ref>{{cite journal |last1=Keller |first1=L. |last2=Ross |first2=K.G. |title=Selfish genes: a green beard in the red fire ant |journal=Nature |date=1998 |volume=394 |issue=6693 |pages=573–575 |bibcode=1998Natur.394..573K |doi=10.1038/29064 |s2cid=4310467 |url=http://bio.classes.ucsc.edu/bioe200b/pdf%20files/AntGreenbeard.pdf |access-date=26 February 2011 |archive-date=20 July 2011 |archive-url=https://web.archive.org/web/20110720074946/http://bio.classes.ucsc.edu/bioe200b/pdf%20files/AntGreenbeard.pdf |url-status=dead }}</ref><ref>{{cite journal |last1=Grafen |first1=A. |title= Evolutionary biology: Green beard as death warrant |journal= Nature |volume=394 |issue=6693 |pages=521–522|date=1998|url=http://users.ox.ac.uk/~grafen/cv/grbeard.pdf|doi=10.1038/28948|bibcode=1998Natur.394..521G|s2cid=28124873 }}</ref> In 2011, scientists announced they had [[Whole genome sequencing|fully sequenced]] the red imported fire ant [[genome]] from a male.<ref>{{cite journal |last1=Wurm |first1=Y. |last2=Wang |first2=J. |last3=Riba-Grognuz |first3=O. |last4=Corona |first4=M. |last5=Nygaard |first5=S. |last6=Hunt |first6=B.G. |last7=Ingram |first7=K.K. |last8=Falquet |first8=L. |last9=Nipitwattanaphon |first9=M. |last10=Gotzek |first10=D. |last11=Dijkstra |first11=M.B. |last12=Oettler |first12=J. |last13=Comtesse |first13=F. |last14=Shih |first14=C.-J. |last15=Wu |first15=W.-J. |last16=Yang |first16=C.-C. |last17=Thomas |first17=J. |last18=Beaudoing |first18=E. |last19=Pradervand |first19=S. |last20=Flegel |first20=V. |last21=Cook |first21=E.D. |last22=Fabbretti |first22=R. |last23=Stockinger |first23=H. |last24=Long |first24=L. |last25=Farmerie |first25=W.G. |last26=Oakey |first26=J. |last27=Boomsma |first27=J.J. |last28=Pamilo |first28=P. |last29=Yi |first29=S.V. |last30=Heinze |first30=J. |last31=Goodisman |first31=M. A.D. |last32=Farinelli |first32=L. |last33=Harshman |first33=K. |last34=Hulo |first34=N. |last35=Cerutti |first35=L. |last36=Xenarios |first36=I. |last37=Shoemaker |first37=D. |last38=Keller |first38=L. |title=The genome of the fire ant ''Solenopsis invicta'' |journal=Proceedings of the National Academy of Sciences |date=2011 |volume=108 |issue=14 |pages=5679–5684 |doi=10.1073/pnas.1009690108 |pmid=21282665 |pmc=3078418 |bibcode=2011PNAS..108.5679W |doi-access=free }}</ref>