Natural History:
Wasmannia auropunctata is a pest ant about which much has been written (e.g., Clark et al. 1982, De Souza et al 1998, Fabres and Brown 1978, Jourdan 1997, Lubin 1984, Ulloa Chac?n and Cherix 1990, Williams 1994). The species is remarkably catholic in its habitat preference. It can be abundant in primary forest or young second growth, wet forest or dry forest, although it is perhaps most abundant in disturbed habitats. It can be an agricultural pest in many parts of the tropics because of its strong sting.
The sting of Wasmannia is worth commenting on. These are extremely tiny ants, barely visible in the field. When I first began studying ants in Costa Rica, for a while I was puzzled about Wasmannia. By literature and reputation Wasmannia was reputed to have a terrible sting, but I had been collecting them for months in Corcovado National Park and never experienced the famous sting. Then one day I was collecting from a populous nest and some workers made it up to the soft skin of my inner forearm and began to sting. The sting was not terrible, about as bad as a fire ant (i.e., Solenopsis geminata) but inordinately strong for an ant you could barely see! I then learned that they are so small they cannot sting through the thicker skin of your hands. I subsequently learned that necks are nice places to get stung. Often when crawling through trashy second growth or Heliconia thickets my neck would start to burn. I would reach around to find the culprit and find nothing there. This was my cue that it was Wasmannia, and often a close inspection would reveal that I had brushed into a nest and workers were scattered on my head and shoulders.
Colonies are polygynous and it is never clear where colony boundaries are. Dozens of dealate queens may be found together in nests. Nests can be almost anywhere: in rolled leaves or dead sticks in the leaf litter, under stones, in rotten wood, in hollow stems suspended above the ground, in ant-plant domatia, and under epiphytes. Workers are omnivorous scavengers and predators and can rapidly recruit to food.
Taxonomic history
[Misspelled as aurata by Menozzi, 1935b PDF: 196.].Wheeler & Wheeler, 1954d PDF: 444 (l.).Combination in Ochetomyrmex: Forel, 1886b PDF: xlix.Combination in Tetramorium (Xiphomyrmex): Forel, 1887 PDF: 384.Combination in Wasmannia: Forel, 1893j PDF: 383.Status as species: Roger, 1863b PDF: 27; Mayr, 1863a PDF: 456; Forel, 1885a PDF: 375; Forel, 1886b PDF: xlix; Mayr, 1887 PDF: 623; Emery, 1890c PDF: 46; Dalla Torre, 1893 PDF: 130; Forel, 1893j PDF: 383; Emery, 1894l PDF: 53; Forel, 1895b PDF: 126, 143; Forel, 1897b PDF: 300; Forel, 1899b PDF: 54; Forel, 1901d PDF: 128; Forel, 1902b PDF: 177; Wheeler, 1905c PDF: 128; Emery, 1906c PDF: 160; Wheeler, 1908a PDF: 143; Wheeler, 1908b PDF: 161; Forel, 1908c PDF: 44; Wheeler, 1911a PDF: 28; Wheeler, 1911b PDF: 170; Forel, 1912h PDF: 1; Wheeler, 1913b PDF: 486; Wheeler, 1913e PDF: 240; Wheeler & Mann, 1914 PDF: 38; Donisthorpe, 1915f: 341; Mann, 1916 PDF: 448; Wheeler, 1916c PDF: 8; Wheeler, 1916f PDF: 324; Wasmann, 1918a PDF: 75; Luederwaldt, 1918 PDF: 40; Wheeler, 1919e: 304; Mann, 1920b PDF: 428; Mann, 1922 PDF: 33; Wheeler, 1922: 912; Wheeler, 1922e PDF: 11; Wheeler, 1923d PDF: 5; Emery, 1924f PDF: 294; Wheeler, 1925a: 36; Stärcke, 1926a PDF: 88 (in key); Borgmeier, 1927c PDF: 111; Donisthorpe, 1927c: 393; Menozzi, 1927c PDF: 268; Menozzi, 1929b PDF: 3; Menozzi & Russo, 1930 PDF: 162; Smith, 1930a PDF: 4; Menozzi, 1931b PDF: 272; Santschi, 1931d PDF: 271; Wheeler, 1932a PDF: 11; Wheeler, 1935g: 32; Eidmann, 1936a PDF: 48; Wheeler, 1936c PDF: 200; Smith, 1937 PDF: 854; Wheeler, 1942 PDF: 207; Brown, 1948d PDF: 102; Weber, 1948b PDF: 82; Creighton, 1950a PDF: 295; Smith, 1951c PDF: 824; Kusnezov, 1952h PDF: 182 (in key); Kusnezov, 1953c PDF: 338; Smith, 1954c PDF: 7; Smith, 1958c PDF: 135; Kempf, 1961b PDF: 512; Kempf, 1964e PDF: 66; Kempf, 1970c PDF: 335; Kempf, 1972b PDF: 257; Alayo, 1974 PDF: 39; Smith, 1979: 1402; Taylor, 1987a PDF: 81; Zolessi et al., 1988: 4; Deyrup et al., 1989 PDF: 97; Brandão, 1991 PDF: 383; Bolton, 1995b: 423; Deyrup et al., 2000: 298; Deyrup, 2003 PDF: 47; Wetterer & Wetterer, 2004 PDF: 215; Coovert, 2005 PDF: 86; Ward, 2005 PDF: 38; Longino & Fernández, 2007 PDF: 276; Wild, 2007b PDF: 38; Vonshak & Ionescu-Hirsch, 2009 PDF: 45; Branstetter & Sáenz, 2012 PDF: 262; Sarnat et al., 2013 PDF: 72; Wetterer, 2013d 10.1163/18749836-06001068 PDF: 173; Borowiec, 2014 PDF: 206; Ramage, 2014 PDF: 174; Bezděčková et al., 2015 PDF: 122; Cuezzo et al., 2015 PDF: 249 (redescription); Wetterer et al., 2016 PDF: 21; Deyrup, 2017: 158; Fernández & Serna, 2019 PDF: 881; Lubertazzi, 2019 10.3099/MCZ-43.1 PDF: 198.Senior synonym of Wasmannia atomum: Wheeler, 1922: 912; Bolton, 1995b: 423; Longino & Fernández, 2007 PDF: 277.Senior synonym of Wasmannia auropunctata australis: Longino & Fernández, 2007 PDF: 276.Senior synonym of Wasmannia glabra: Kempf, 1964e PDF: 66; Kempf, 1972b PDF: 258; Smith, 1979: 1402; Bolton, 1995b: 423; Longino & Fernández, 2007 PDF: 277.Senior synonym of Wasmannia auropunctata laevifrons: Longino & Fernández, 2007 PDF: 276.Senior synonym of Wasmannia auropunctata nigricans: Longino & Fernández, 2007 PDF: 276.Senior synonym of Wasmannia auropunctata obscura: Longino & Fernández, 2007 PDF: 276.Senior synonym of Wasmannia panamana: Brown, 1948d PDF: 102; Smith, 1954c PDF: 7; Kempf, 1972b PDF: 258; Smith, 1979: 1402; Bolton, 1995b: 423; Longino & Fernández, 2007 PDF: 277.Senior synonym of Wasmannia auropunctata pulla: Longino & Fernández, 2007 PDF: 277.Senior synonym of Wasmannia auropunctata rugosa: Longino & Fernández, 2007 PDF: 276.I [introduced species]
Taxonomic comments
Workers of W. auropunctata have a strongly quadrate petiolar node. The anterior face of the node is sharply differentiated from both the peduncle and the dorsal face of the node, meeting both at nearly right angles, and forming a strongly step-like profile. This is a highly distinctive feature that easily distinguishes auropunctata workers from all other Wasmannia species. Within the species there is abundant variation in the strength of sculpturing and coloration, and this has engendered the naming of nine infraspecific forms in addition to the nominotypical. We have never been able to discover evidence of discrete forms among the workers of auropunctata , either in sympatry or allopatry; the variation appears continuous. Three of the forms have already been synonymized by others: atomum , glabra , and panamana . We have been able to examine types of three additional forms — obscura , pulla , and rugosa — and they fall well within our concept of auropunctata . The remaining forms — australis , laevifrons , nigricans — we have not examined, but the published descriptions give no indication that they are beyond the range of variation of auropunctata . We have synonymized them, following the philosophy that taxa should be synonymized unless evidence of distinctness is obtained.
The above synonymy does not assure that there is no genetic structuring, and perhaps species-level differences, within the broad concept of auropunctata . There may even be distinct sympatric species. In Costa Rica, there appear to be two size classes of queens (Fig. 2). Queens with smaller heads include ten from various sites in Costa Rica, including La Selva Biological Station and the Penas Blancas Valley, one from Jamaica, and one from Venezuela. Queens with large heads are all from the Atlantic slope of Costa Rica. Three are from La Selva (two from different Winkler samples of sifted leaf litter from the forest floor, one from a small nest under an epiphyte mat in an old treefall) and one is an alate queen found in a Cecropia sapling near Volcan Arenal. Thus the small-headed and big-headed forms are broadly sympatric in Costa Rica. Among the small-headed queens four are definitively associated with workers from the same colony, and among the big-headed queens one is associated with workers. Others have workers doubtfully associated (together in the same Winkler sample). We can discern no differences in workers associated with the two types of queens. The cause of the two size classes of queens is unknown, but could reflect either differences between cryptic species or intraspecific polymorphism.
An aberrant worker form is frequently encountered in large samples of W. auropunctata . These aberrant workers have the head grossly swollen. The entire head is more spherical than normal, as if the head were inflated like a balloon. The rest of the body is little different from a normal worker. These aberrant workers are occasionally encountered in Winkler samples that contain hundreds or thousands of auropunctata workers.
Natural History
Wasmannia auropunctata is a widespread pest ant (Clark et al., 1982; De Souza et al., 1998; Fabres & Brown, 1978; Jourdan, 1997; Lubin, 1984; Ulloa Chacon & Cherix, 1990; Williams, 1994; Wetterer & Porter, 2003). In its presumed native range it occurs from Argentina to Mexico (Kempf, 1972; Wetterer & Porter, 2003). Its introduced range includes the Galapagos Islands, West Africa (Gabon, Cameroon, and possibly the Republic of Congo and the Democratic RepubIic of Congo), Melanesia (New Caledonia, Solomon Islands, Vanuatu, and possibly Tuvalu), Polynesia (Wallis and Futuna and Hawaii), parts of the US (Florida and possibly California), and subtropical Atlantic islands (the Bahamas and Bermuda) (Wetterer & Porter, 2003). It is widespread on Caribbean islands, but it is unclear whether these are long-term native populations or recent introductions (Wetterer & Porter, 2003).
The species is remarkably catholic in its habitat preference. It is common in habitats ranging from wet to dry and from early successional to mature. In an elevational gradient of mature wet forest on the Atlantic slope of Costa Rica (the Barva Transect, from La Selva Biological Station to 2000 m elevation on the slope of Volcan Barva) it is abundant at 50 m and 500 m elevations, but nearly absent at 1070 m (Table 2). In the lowland habitats where it is abundant, it occurs in leaf litter on the forest floor and at all levels in the vegetation.
Although it occurs frequently in samples from mature forest habitats in Costa Rica, it is never so abundant in those habitats that it is noticeable as a pest or appears to be displacing other native species (Tennant, 1994; McGlynn & Kirksey, 2000; pers. obs.). In contrast, in certain agricultural habitats (banana plantations) and in parts of the tropics where it has been introduced it becomes super-abundant, with negative impacts on native species and human comfort (Clark et al., 1982; Wetterer & Porter, 2003). In dry-forest fragments in Colombia there is a negative correlation between W. auropunctata abundance and overall ant diversity (Armbrecht & Ulloa Chacon, 2003). Where introduced in New Caledonia it invades dense native forest and displaces native ants (Le Breton et al., 2003). Behavioral tests and cuticular hydrocarbon analysis show that W. auropunctata is multicolonial in its native range in Brazil, unicolonial where introduced in New Caledonia (Errard et al., 2002).
The sting of Wasmannia is noteworthy. These are extremely tiny ants, barely visible in the field. When the senior author first began studying ants in Costa Rica, he was at first puzzled about Wasmannia . By literature accounts Wasmannia was reputed to have a terrible sting, but he had been collecting them for months in Corcovado National Park without ever experiencing the famous sting. One day he was collecting from a populous nest and some workers made it up to the soft skin of his inner forearm and began to sting. The sting was definitely noticeable, about as severe as a fire ant (i. e., Solenopsis geminata ) but inordinately strong for an ant that could barely be seen! Workers are so small they cannot sting through the thicker skin of the hands.
Surprisingly, the chemical and toxicological nature of the venom of W. auropunctata has not been investigated. Howard et al. (1982) discovered an alkylpyrazine compound in the mandibular glands, which acted as an attractant to conspecifics and a repellent to heterospecifics. They speculated that the workers might apply the mandibular gland product as an irritating secretion, augmenting the defensive properties of the venomous sting. It would be interesting to investigate whether the venom alone is the powerful agent in this small ant, or if the strong burning sensation is a synergetic effect of venom plus mandibular gland product.
Nests can be almost anywhere: in rolled leaves or dead sticks in the leaf litter, under stones, in rotten wood, in hollow stems suspended above the ground, in ant-plant domatia, and under epiphytes. Workers are omnivorous scavengers and predators and can rapidly recruit to food. Colonies are polygynous and it is never clear where colony boundaries are. Dozens of dealate queens may be found together in nests. Males are rare but do occasionally occur.
Boquerón , Caaguazú , Canindeyú , Central, Pte. Hayes (ALWC, IFML, INBP, LACM, MHNG MSCN, MZSP). Literature records: Alto Paraná , Concepción (Emery 1894a, Emery 1906, Forel 1907b; [also as “ australis ”, “ nigricans ”, and “ rugosa ”]).
(No. 39 a, b, c, d, e, f, g, h, i, j, k, l, vi, n, o, q, r, s, t, u, et 48 c bis), [[ worker ]] [[ queen ]] [[ male ]], [[ queen ]] (Inedite). L. 4 a 4, 3 mill.; thorax large de 1, 0 a 1,1, abdo- men de 1, 3 mill. Le thorax beaucoup plus large que la tete. Tete beaucoup plus large que longue et beaucoup plus large derriere que devant, largement concave derriere. Occiput subtronque. Pronotum epaule devant. Mesonotum subdeprime. Metanotum pourvu de deux epines extremement larges, triangulaires et assess longues qui se prolongent en aretes un peu translucides jusqu'au lobule metasternal qui est lamelliforme. Premier article du pedi- cule avec un petiole beaucoup plus long et plus fort, et un n oe ud plus court que chez l'ouvriere.
Tete et thorax longitudinalement rides-stries, mats et tres finement reticules-ponctues entre les rides. Pedicule et 1 er segment de l'abdomen tres finement et densement reticules-ponctues et mats (le dernier en partie reticule et subopaque ainsi que les pattes). Le pedicule a en outre quelques impressions longitudinales. Les autres segments abdominaux tres faiblement chagrines et luisants. Le premier segment de l'abdomen n'a pas les gros points enfonces de la [[ worker ]] et du [[ male ]].
D'un brun roussatre ou jaunatre, ferrugineux. Dessus de la tete et du thorax ainsi que le milieu des segments abdominaux d'un brun chatain. Ailes teintes de brunatre, pubescentes; nervures et tache marginale brunes. Du reste comme l'ouvriere, en particulier la pilosite et la pubescence, les aretes frontales, etc.
[[ male ]] (inedit). L. 4, 2 mill. Yeux grands, rapproches du bord anterieur de la tete. Mandibules dentees. Epistome sans carene. Scapes longs comme les deux premiers articles du funicule reunis. Premier article du funicule tres court, a peine plus long que large; second article d' 1 / 4 plus long que le 3 me. Face basale du meta- notum bien plus longue que la face declive; metanotum portant deux tubercules lateraux allonges. Premier article du pedicule avec un petiole large et un n oe ud arrondi, fortement elargi vers sa base. Valvules genitales exterieures terminees par deux immenses appendices longs, etroits, recourbes en bas, faiblement elargis vers leur extremite, longs comme les 2 / 3 de l'abdomen et depassant d'autant son extremite. Ces singuliers appendices qui ne sont qu'un prolongement demesure de l'extremite des valvules exte- rieures, donnent a ce male un aspect tout particulier. Mesonotum avec un large sillon median anterieur, deux sillons convergents et deux sillons lateraux posterieurs.
Tete et thorax densement reticules-ponctues et mats, avec quelques rides (quelques stries sur la tete). Metanotum en outre fortement ride en long. Pedicule reticule et subopaque. Abdomen luisant, faiblement reticule; sur le premier segment de gros points enfonces irreguliers. Pilosite et pubescence comme chez la [[ queen ]] et l'ouvriere, mais plus pointue et plus fine.
D'un brun fonce ou noiratre. Cotes du thorax, pattes et funicules d'un brun jaunatre sale. Mandibules, scapes, tarses, extre- mite des segments abdominaux, et appendices genitaux d'an jaunatre sale. Ailes d'une teinte un peu plus noiratre que chez la [[ queen ]].
(39). A very common species. The communities ave generally rather small, but may be composed of several hundred, or even a thousand, individuals. The formicaria are very simple, advantage being taken of a space among rotting leaves on the ground, or there is a single chamber - sometimes two or three close together - - under a stone or stick, at the roots of grass, or under bark, nearly always in a damp place. In this the ants are found closely packed, with a single female, or several, if the community is large, and the eggs and larvas. The workers are sluggish in their movements, and the females still more so. The workers are frequently found on foliage, forest or open land.
(39 a). Oct. 11 th (leeward). Forest above Chateau- belais, 1000 ft.; under a stick.
(39 b). Near Fort Charlotte, Kingstown, 500 ft. Oct. 25 th. Small nest under the side of a stone; thickets. Several males but no female found.
(39 c). Fitz-Hugh Valley (leeward), 500 ft. Nov. 4 th. Open place. Nest under log, and partly under the bark, with several chambers.
(39 d). Several nests. Localities and dates, not noted.
(39 e). Near Golden Grove House (leeward), 500 ft. Oct. 6 th. Coco orchards, among rotting leaves, under stones, & c. Several colonies; in one large one (several hundred workers) I could find no female. Some were taken on foliage.
(39 f). Same locality and date as No. 89 e. A small colony, under a stone.
(39 g). Bowwood Valley, near Kingstown, 800 ft. Oct. 21 st. Open place under a stone. Small colony.
(39 h). Near Palmyra Estate (leewardi, 1000 ft. Nov. 3 rd. Open place; under a log; between rotting leaves.
(39 i). Wallilobo Valley (leeward), Nov. 5 th. 5000 ft. Forest. Small nest under sod on a rock.
(39 j). Wallibou (leeward); seashore thickets. Oct. 7 th. Small nest under a stone.
(39 k). Old Botanical Garden, Kingstown; second growth. A small nest, in rotting-wood.
(39 l). Forest above Chateaubelais, 1000 ft. March. A single female, under rotting leaves.
(39 m). Open land and forest, 1500 ft. to sea-level. Beaten from foliage. Various localities and dates.
(39 n). Various localities and dates; forest or open land below 2000 ft. Taken from small nests, or found among rotting leaves.
(39 o). Southern end of island; Villa Estate. Oct. 14 th. Seashore thicket. Small nest under a block of coral (doubtfully referred to this species).
(39 q). Petit Bordelle Valley, 1600 ft. Nov. 13 th. Clearing. A small nest in rotten wood.
(39 r). Camden Park Estate (leeward), north of Kingstown. Nov. 19 th. Small nest under the bark of a palm-log; seaside thicket. No female could be found.
(39 s). Windward side, Robocca to Grand Sable Estate. Jan .. 2 nd and 3 rd. From several nests in various localities near the seashore; under stones.
(39 t). Windward, Grand Sable Estate; open place near the sea. Community of about 500, under a stone. Jan. 3 rd.
(32 u). Sandy bed of Dry River (windward), near sea. Jan. 2 nd. Under a stone. Associated with No. 34 c.
(48 c bis). Females found without workers; under sod on rocks; different localities near sea-level (leeward), and south end of island. November.
[[ worker ]]. La Caja, pres San Jose de Costa Rica, 1100 metres, Costa Rica (P. Biolley), Costa Rica (J. - F. Tristan).
The little fire ant (Wasmannia auropunctata), also known as the electric ant, is a small (approx 1.5 mm (1⁄16 in) long), light to golden brown (ginger) social ant native to Central and South America, now spread to parts of Africa (including Gabon and Cameroon), Taiwan,[2] North America, Puerto Rico,[3] Israel,[4][5] Cuba, and six Pacific Island groups (including the Galápagos Islands, Hawaii, New Caledonia and the Solomon Islands) plus north-eastern Australia (Cairns).[6] It is a very harmful invasive species.
The name, electric ant (or little fire ant), derives from the ant's painful sting relative to its size.[7]
The ant is described as follows:[8]
Wasmannia auropunctata workers are monomorphic, which means they display no physical differentiation... The ants are typically small to medium-sized, with the workers ranging from 1-2mm ... [It] is light to golden brown in color. The gaster is often darker. The pedicel, between the thorax and gaster, has two segments; the petiole and postpetiole. The petiole is "hatchet-like", with a node that is almost rectangular in profile and higher than the postpetiole. The antennae have 11 segments, with the last two segments greatly enlarged into a distinct club. The antennal scape (the first segment) is received into a distinct groove (scrobe) that extends almost to the posterior border of the head. The thorax has long and sharp epinotal spines. The body is sparsely covered with long, erect hairs. This species is well-known for a painful sting, seemingly out of proportion to its size.
In Wasmannia auropunctata, queens produce more queens through parthenogenesis. Sterile workers usually are produced from eggs fertilized by males. In some of the eggs fertilized by males, however, the fertilization can cause the female genetic material to be ablated from the zygote. In this way, males pass on only their genes to become fertile male offspring. This is the first recognized example of an animal species where both females and males can reproduce clonally resulting in a complete separation of male and female gene pools.[9][10]
These ants get the benefits of both asexual and sexual reproduction[9][11] - the daughters who can reproduce (the queens) have all of the mother's genes, while the sterile workers whose physical strength and disease resistance are important are produced sexually.
Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilization. Thelytoky is a particular form of parthenogenesis in which the development of a female individual occurs from an unfertilized egg. Automixis is a form of thelytoky, but there are several kinds of automixis. The kind of automixis relevant here is one in which two haploid products from the same meiosis combine to form a diploid zygote.
W. auropunctata thelytokous queens from clonal populations can reproduce by automictic parthenogenesis involving central fusion of haploid meiotic products, a process that allows conservation of heterozygosity in progeny.[12] The same parthenogenic queens that produce progeny by automixis may also produce normally segregating meiotic oocytes, which upon fertilisation by males give rise to diploid workers.
The oocytes that undergo automixis display much lower rates of crossover recombination (by a factor of 45) than the oocytes produced by sexually reproducing queens that give rise to workers. These low recombination rates in automictic oocytes favor maintenance of heterozygosity, and allow only very low rates of transition from heterozygosity to homozygosity (0 to 2.8%).[12] The sharp decrease in recombination rates likely allows clonal queens using automixis to benefit from thelytoky (transmission of their entire genomes to individual progeny), while also avoiding the potential for inbreeding depression that would result from random fusion of meiotic products leading to loss of heterozygosity.
In general, parthenogenesis appears to be favored in recently disturbed habitats (such as produced by floods, fires and glaciers).[13] The clonal populations of W. auropunctata are mostly found in habitats disturbed by recent human activity.[12]
The native range of the little fire ant is in almost all portions of South America and Central America, excluding colder climate regions. Little fire ants are habitat generalists that tend to colonize areas associated with humans in warmer regions. These habitats include forest edges, managed forests, agricultural fields and plantations.[14][15] Little fire ants are generalists that consume other insects, decaying vegetation, seeds, and plants. These ants also consume honeydew and engage in mutualistic symbiotic relationships with other herbivorous insects, such as aphids.[14][15] The little fire ants are effective predators that have a venomous sting that can subdue large insects and vertebrate prey.[16]
Little fire ants establish colonies under rocks and plant litter. These ants are also considered a residential pest as they establish colonies in furniture, food, and clothing in people's homes. Colony movement can be amplified after a heavy rainstorm.[17][18]
The little fire ant has been introduced on plantations in Gabon and Cameroon to be used as a biological control agent.[8] The species has been unintentionally transported from its native range to Africa, North America, Puerto Rico, Cuba, Israel, Taiwan,[2] and multiple Pacific Island groups.[15][17] Invading ants cannot survive in global regions that have cold environments. But, little fire ants are found in Canada and England where they find refuge in large human infrastructure and greenhouses.[19] Human disturbed landscapes – such as the practice of monocultures, and the deforestation of land – have caused an explosion in the little fire ant population in regions of Brazil and Colombia which have a prevalence of cocoa farms and sugarcane monocultures. In Colombia, research shows that high abundance little fire ant populations reduce other ant diversity in heavily deforested regions.[18]
The little fire ant preys on native insects, causing a decline in population densities, and they can also attack small to medium-sized vertebrates if the ant colonies are disturbed.[14] Throughout their invasive and native range, the little fire ant reduces native ant diversity when successfully colonized.[20] These ants successfully outcompete the other ants because they exploit a multitude of resources other species need to survive, including honeydew residues, nectar and refuges in vegetation.
Pets and large domestic animals (such as cats and dogs) stung around the eyes by this ant are known to develop blindness.[15] In the Galapagos Islands, the little fire ant is regarded as one of the most aggressive species introduced to this region. The ant has contributed to the decline in tortoise populations, as these ants eat the tortoise hatchlings and attacks the eyes of adult tortoises. Furthermore, large population declines of scorpions, spiders, and native ants can be directly attributed to the invasive ant.[21][22][23]
When humans are encountered, these ants have a powerful sting in proportion to its size. The sting causes inch long welts that are itchy and painful. Some workers and farmers may have issues properly harvesting crops in high density little fire ant agricultural areas.[17]
Research shows that the ant can strip nutrients from agricultural plants, which increases crop susceptibility to disease and other herbivorous insect pests. As a result of the ant's presence in agricultural fields, crop yields diminish, and have a negative economic effect on any particular agricultural industry affected by the ant.[17]
There are several proposed control and prevention strategies that have been taken to help minimize or eradicate the little fire ant. The Pacific Ant Prevention Program is a proposal that illustrates prevention methods within the islands located throughout the Pacific region in Polynesia (such as Hawaii and Futuna) for invasive ant species including the little fire ant. The program was initiated to provide improved quarantine protocols for the Polynesian area, in addition to raising awareness of the possible impact of the little fire ant.[20] In 1999, the Hawaiian State Department of Agriculture proposed a 100% inspection policy on all plant material exported from the state to check for the ant so that it cannot spread to other regions.[15]
Generally, better agricultural land management—including the reduction of monocultures and lower crop production—can reduce little fire ant populations. In addition, proper land management plans can alleviate ant population spikes that occur in highly degraded areas. When first constructing an agricultural field, minimizing landscape changes—such a deforestation—can prevent or reduce the population density of the little fire ant.[18]
Chemicals and pesticides have been employed in smaller density ant populations in the Galapagos Islands. These little fire ant populations were no bigger than approximately 24 hectares.[23] Other control methods such as non-selective ant poisons, fire and vegetation clearing have been successful on small ant populations and small islands.
There is a strong suspicion of a link between Florida keratopathy or tropical keratopathy and presence of W. auropunctata.[24]
The little fire ant (Wasmannia auropunctata), also known as the electric ant, is a small (approx 1.5 mm (1⁄16 in) long), light to golden brown (ginger) social ant native to Central and South America, now spread to parts of Africa (including Gabon and Cameroon), Taiwan, North America, Puerto Rico, Israel, Cuba, and six Pacific Island groups (including the Galápagos Islands, Hawaii, New Caledonia and the Solomon Islands) plus north-eastern Australia (Cairns). It is a very harmful invasive species.
The name, electric ant (or little fire ant), derives from the ant's painful sting relative to its size.
W. auropunctata biting a human
