Wasmannia auropunctata
| Little fire ant | ||||||||||||
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Wasmannia auropunctata (Image: April Nobile, Antweb.org) |
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| Scientific name | ||||||||||||
| Wasmannia auropunctata | ||||||||||||
| ( Roger , 1863) |
The small fire ant , scientific name Wasmannia auropunctata, is a species of ant originally native to South America, which today has been introduced and naturalized by humans almost all over the world. It is considered a pest wherever it occurs . The name fire ant is derived from the unpleasant sting that is remarkable for such a small insect. It is called a “small” fire ant not only because of its small size, but also to distinguish it from the “large” fire ant Solenopsis invicta , to which it is not closely related. The generic name was given in honor of the "ant father" Erich Wasmann .
features
Workers of the species are small ants with a body length of barely 1.5 millimeters. They are colored yellow-brown to orange in color. As is typical for members of the subfamily Myrmicinae, the free abdomen ( gaster ) is separated from the trunk section (alitrunk or mesosoma) by two thickened stalk members, called petiolus and postpetiolus. The shape of the Petiolus is typical of the species and the most important distinguishing feature from other Wasmannia species. This is knot-like thickened with a rectangular shape in profile, with the other species always rounded in profile. The head carries eleven-segment antennas, the last two links of which form a detached antenna lobe. The elongated basal part of the antennae, the scapus, extends backwards over the edge of the eye, but not over the edge of the head, when the antenna is laid back. The mandibles are triangular and the chewing bar has five small teeth. The complex eyes are relatively large, with more than 10 ommatidia. Two keels on the top of the head are striking, the frontal keels, which in this species reach to the rear edge of the head and delimit two weakly sunk antennae pits. The trunk section is rounded in profile, it has long bristles (setae). The propodeum has two long, pointed thorns. The animals have a functional poison sting that they can use to penetrate human skin. Wasmannia auropunctata is similar to the small lawn ants of the genus Tetramorium , but can be distinguished from them by the long, pointed thorns on the propodeum and the only eleven-segment antennae with a two-part club.
Queens of the species are much larger than the worker, they reach about 4.5 millimeters in length, and are dark in color.
Way of life
The little fire ant usually nests above the ground, in the litter and under stones, and in all kinds of crevices and hollows, both in plants and in man-made structures. It is not picky about the habitat and occurs equally in sunny and shaded habitats. Although it is not completely absent in undisturbed primary forests, it reaches higher densities especially in habitats and cultivated land that have been disturbed by humans. Here it can often be the most common and most individual ant species.
The most important food source of the species is honeydew from aphid or scale insect colonies that it maintains and defends; it also likes to use nectar from extra-floral nectaries . The species forms large colonies with several queens, so it is polygynous . New colonies are created by sprouting, when one or more young queens leave the nest together with a number of workers. While it is highly aggressive towards other ant species, colonies of the species are peaceful with one another. This is partly due to the special method of reproduction in which young queens are generated through parthenogenesis, i.e. can be regarded as clones . This goes so far that queens, brood and workers move back and forth between many different colonies without barriers. These are therefore often viewed as a common “ super colony ” that still belongs together . For example, all the colonies on the island of New Caledonia form a super colony 450 kilometers in length. This applies in particular to the introduced, invasive populations of the species, while it occurs in the natural range, but here mainly in habitats disturbed by humans.
The mode of reproduction of the species is remarkable, it was described by Denis Fournier and colleagues in 2005. They found that the queens were often genetically identical both within a nest and in neighboring nests, that is, obviously due to (ameiotic) parthenogenesis. The analysis also showed that the males are genetically identical to one another - but with a different genotype than the queens. Female workers were genetically different from one another and evidently resulted from normal sexual reproduction. They attribute the fact that sexual reproduction was retained in the female workers to the advantages that genetically diverse animals have over parasites and pathogens, for example. As long as this mode of reproduction continues, it prevents any gene flow between males and females of the species, which could cause them to develop genetically apart. However, later studies have shown that, in addition to clonal reproduction, the species also reproduces sexually, more frequently in natural habitats, but occasionally also in introduced populations.
habitat
The natural range of the species lies in South and Central America ( Neotropic ), it ranges from central Mexico to Uruguay and the north of Argentina. According to some information, the populations in northern Mexico as far as the extreme south of the USA are autochthonous, others assume that animals were introduced here. The status on the West Indies is just as controversial ; at least today it occurs on almost all islands, but is possibly native to a number of them. The type locality of the species is the island of Cuba .
The small body size of the species, its ecological plasticity and the way in which colony was founded by sprouting and its colonization of man-made substrates have resulted in the species being transported to warm regions almost worldwide. It was found in Africa (in Gabon and Sierra Leone ) as early as the 19th century and has since reached other parts of Africa. Its triumphal march in Oceania began in the 20th century. It reached New Caledonia in 1972, the Solomon Islands in 1974 , Tuvalu in 1997 and Hawaii in 1999 . It has also been found in Australia since 2002 and in New Guinea since 2005 . Israel has also been settled since 1998 . This shows that it can live in regions with more than 5 months of dry season as well as in areas with minimum temperatures well below tropical conditions. The minimum temperatures of the populated areas in Israel are widespread below 9 ° C, in one case even below 6 ° C. In a temperate climate with night frosts, the species cannot live outdoors. Here, however, colonies have repeatedly been observed in warm greenhouses, the first as early as 1907 in Kew Gardens , England.
Effects
The species is classified as an economic pest. The main problems are crop damage caused by stings by workers while working in the fields, as well as damage to plants by plant-sucking aphids and scale insects that it promotes and spreads. In addition, cases of blindness due to stitches in the eyes are reported in both domestic and wild animals. However, the ecological consequences of their spread are seen as far more important. The most serious effects are given for tropical islands. Their effects on other species of ants are particularly serious. It is capable of literally displacing all other ant species that occur over large areas. On the Galapagos , not only did the ants that live there disappear in the areas populated by the small fire ant, but also other arthropods (with the exception of aphids ) became significantly less common. The displacement of the native ant fauna is now also reported from the regions of Israel that the species has already reached. Based on these reports, the species is included on the list of the 100 worst invasive species worldwide published by the IUCN (see List of the 100 Most Dangerous Neobiota )
Taxonomy
The genus Wasmannia includes ten species, all of which except Wasmannia auropunctata are restricted to South America, often with a relatively small distribution area. The genus Blepharidatta is considered to be closely related . According to recent analyzes, the genus is classified together with the leaf cutter ants of the Atta genus in the Attini tribe.
Individual evidence
- ^ A b John T. Longino & Fernando Fernández (2007): Taxonomic review of the genus Wasmannia. In: RR Snelling, BL Fisher, PS Ward (editors): Advances in ant systematics (Hymenoptera: Formicidae): homage to EO Wilson - 50 years of contributions. Memoirs of the American Entomological Institute 80: 271-289.
- ^ Brian L. Fisher, Stefan P. Cover: Ants of North America. A Guide to the Genera. University of California Press, 2007. ISBN 9780520934559
- ↑ electric ant at Antkey
- ↑ a b c James K. Wetterer & Sanford D. Porter (2003): The Little Fire Ant, Wasmannia auropunctata: Distribution, Impact and Control. Sociobiology vol.41 no.3: 1-41. download ( Memento of the original from October 30, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b J. Foucaud, J. Orivel, D. Fornier, JHC Delabie, A. Loiseau, J. le Breton, P. Cerdan, A. Estoup (2009): Reproductive system, social organization, human disturbance and ecological dominance in native populations of the little fire ant, Wasmannia auropunctata. Molecular Ecology 18: 5059-5073. doi : 10.1111 / j.1365-294X.2009.04440.x
- ↑ Denis Fournier, Arnaud Estoup, Jerome Orive, Julien Foucaud, Herve´ Jourdan, Julien Le Breton, Laurent Keller (2005): Clonal reproduction by males and females in the little fire ant. Nature Vol 435: 1230-1234. doi : 10.1038 / nature03705
- ↑ Julien Foucaud, Hervé Jourdan, Julien Le Breton, Anne Loiseau, Djoël Konghouleux, Arnaud Estoup (2006): Rare sexual reproduction events in the clonal reproduction system of introduced populations of the little fire ant. Evolution, 60 (8): 1646-1657.
- ↑ a b James K. Wetterer (2013): Worldwide spread of the little fire ant, Wasmannia auropunctata (Hymenoptera: Formicidae). Terrestrial Arthropod Reviews 6: 173-184. doi : 10.1163 / 18749836-06001068
- ↑ a b Merav Vonshak, Tamar Dayan, Armin Ionescu-Hirsh, Amnon Freidberg, Abraham Hefetz (2010): The little fire ant Wasmannia auropunctata: a new invasive species in the Middle East and its impact on the local arthropod fauna. Biological Invasions 12: 1825-1837. doi : 10.1007 / s10530-009-9593-2
- ^ Bert Hölldobler, Edward O. Wilson: The Ants. Harvard University Press, 1990. ISBN 9780674040755 . p.94.
- ↑ Wasmannia auropunctata. Global invasive species database
- ↑ Philip S. Ward, Sean G. Brady, Brian L. Fisher, Ted R. Schultz (2014): The evolution of myrmicine ants: phylogeny and biogeography of a hyperdiverse ant clade (Hymenoptera: Formicidae). Systematic Entomology (online before print) doi : 10.1111 / syen.12090
