The little fire ant (''Wasmannia auropunctata''), also known as the electric ant, is a small (approx long), light to golden brown (ginger)
social
Social organisms, including human(s), live collectively in interacting populations. This interaction is considered social whether they are aware of it or not, and whether the exchange is voluntary or not.
Etymology
The word "social" derives from ...
ant
Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...
native to Central and South America, now spread to parts of Africa (including Gabon and Cameroon),
Taiwan
Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...
,
North America,
Puerto Rico
Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...
,
Israel, Cuba, and six
Pacific Island
Collectively called the Pacific Islands, the islands in the Pacific Ocean are further categorized into three major island groups: Melanesia, Micronesia, and Polynesia. Depending on the context, the term ''Pacific Islands'' may refer to one of se ...
groups (including the
Galápagos Islands
The Galápagos Islands (Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuador ...
,
Hawaii
Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...
,
New Caledonia and the
Solomon Islands
Solomon Islands is an island country consisting of six major islands and over 900 smaller islands in Oceania, to the east of Papua New Guinea and north-west of Vanuatu. It has a land area of , and a population of approx. 700,000. Its capit ...
) plus north-eastern Australia (
Cairns).
[Electric ant (''Wasmannia auropunctata'') webpage](_blank)
Accessed 7 March 2009 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.
[Queensland Government Electric Ant: Warning](_blank)
Accessed 7 March 2009
Description
The ant is described as follows:
[''Wasmannia auropunctata''](_blank)
Global Invasive Species Database, 31 Oct 2009 (archived)
''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 ... tis light to golden brown in color. The gaster is often darker. The pedicel
Pedicle or pedicel may refer to:
Human anatomy
*Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures
...
, between the thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
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.
Reproduction
In ''Wasmannia auropunctata'', queens produce more queens through
parthenogenesis
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and developmen ...
. 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.
These ants get the benefits of both asexual and sexual reproduction
- 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.
Automixis
Parthenogenesis
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and developmen ...
is a natural form of reproduction in which growth and development of embryos occur without fertilization
Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proce ...
. Thelytoky
Thelytoky (from the Greek ''thēlys'' "female" and ''tokos'' "birth") is a type of parthenogenesis in which females are produced from unfertilized eggs, as for example in aphids. Thelytokous parthenogenesis is rare among animals and reported in a ...
is a particular form of parthenogenesis in which the development of a female individual occurs from an unfertilized egg. Automixis
''Automixis'' is the fusion of (typically haploid) nuclei or gametes derived from the same individual. The term covers several reproductive mechanisms, some of which are parthenogenetic.
Diploidy might be restored by the doubling of the chromoso ...
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
Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately r ...
combine to form a diploid zygote
A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism.
In multicell ...
.
''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
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism.
Mo ...
in progeny. The same parthenogenic queens that produce progeny by automixis may also produce normally segregating meiotic oocyte
An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The femal ...
s, 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
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism.
...
(0 to 2.8%). 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
Inbreeding depression is the reduced biological fitness which has the potential to result from inbreeding (the breeding of related individuals). Biological fitness refers to an organism's ability to survive and perpetuate its genetic material. ...
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). The clonal populations of ''W. auropunctata'' are mostly found in habitats disturbed by recent human activity.
Ecology
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. 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 aphid
Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...
s. The little fire ants are effective predators that have a venomous sting that can subdue large insects and vertebrate prey.
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.
Invasive species
The little fire ant has been introduced on plantation
A plantation is an agricultural estate, generally centered on a plantation house, meant for farming that specializes in cash crops, usually mainly planted with a single crop, with perhaps ancillary areas for vegetables for eating and so on. The ...
s in Gabon
Gabon (; ; snq, Ngabu), officially the Gabonese Republic (french: République gabonaise), is a country on the west coast of Central Africa. Located on the equator, it is bordered by Equatorial Guinea to the northwest, Cameroon to the nort ...
and Cameroon
Cameroon (; french: Cameroun, ff, Kamerun), officially the Republic of Cameroon (french: République du Cameroun, links=no), is a country in west-central Africa. It is bordered by Nigeria to the west and north; Chad to the northeast; the C ...
to be used as a biological control agent. The species has been unintentionally transported from its native range to Africa, North America, Puerto Rico
Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...
, Cuba
Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...
, Israel
Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...
, Taiwan
Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...
, and multiple Pacific Island
Collectively called the Pacific Islands, the islands in the Pacific Ocean are further categorized into three major island groups: Melanesia, Micronesia, and Polynesia. Depending on the context, the term ''Pacific Islands'' may refer to one of se ...
groups. 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. Human disturbed landscapes – such as the practice of monoculture
In agriculture, monoculture is the practice of growing one crop species in a field at a time. Monoculture is widely used in intensive farming and in organic farming: both a 1,000-hectare/acre cornfield and a 10-ha/acre field of organic kale are ...
s, and the deforestation
Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
of land – have caused an explosion in the little fire ant population in regions of Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
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.
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. Throughout their invasive and native range, the little fire ant reduces native ant diversity when successfully colonized. 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. 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.
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.
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.
Control strategies
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
Polynesia () "many" and νῆσος () "island"), to, Polinisia; mi, Porinihia; haw, Polenekia; fj, Polinisia; sm, Polenisia; rar, Porinetia; ty, Pōrīnetia; tvl, Polenisia; tkl, Polenihia (, ) is a subregion of Oceania, made up of ...
(such as Hawaii
Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...
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. 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.
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.
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. Other control methods such as non-selective ant poisons, fire and vegetation clearing have been successful on small ant populations and small islands.
Keratopathy
There is a strong suspicion of a link between Florida keratopathy or tropical keratopathy and presence of ''W. auropunctata''.
References
External links
University of Hawaii Alert: "Identifying the little Fire Ant" (includes photo)
small>Accessed 8 March 2009
little Fire Ant in French Polynesia
Australian Pests and Diseases: ''Wasmannia auropunctata'' (images & description)
*
{{DEFAULTSORT:Electric Ant
Insects of Puerto Rico
Myrmicinae
Hymenoptera of South America
Insects described in 1863