Argentine ant | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Hymenoptera |
Family: | Formicidae |
Subfamily: | Dolichoderinae |
Genus: | Linepithema |
Species: | L. humile |
Binomial name | |
Linepithema humile (Mayr, 1868) | |
The Argentine ant (Linepithema humile, formerly Iridomyrmex humilis) is an ant native to northern Argentina, Uruguay, Paraguay, Bolivia and southern Brazil. [1] This invasive species was inadvertently introduced by humans on a global scale [2] [3] [4] and has become established in many Mediterranean climate areas, [5] [6] [7] [8] including South Africa, [9] New Zealand, [10] Japan, [11] Easter Island, [12] Australia, [13] the Azores, [14] Europe, [15] Hawaii, [16] and the continental United States. [17] Argentine ants are significant pests within agricultural and urban settings, [18] [19] [20] and are documented to cause substantial harm to communities of native arthropods, [21] [22] [23] vertebrates, [24] [25] [26] and plants [27] [28] [29] within their invaded range.
Linepithema humile is a small-bodied (2.2–2.6 mm) ant species, dull light to dark brown in color. Within the invasion zone, ant colonies are large and include many workers and multiple queens. [30]
Argentine ants are opportunistic with regard to nesting preferences. Colony nests have been found in the ground, in cracks in concrete walls, in spaces between boards and timbers, even among belongings in human dwellings. In natural areas, they generally nest shallowly in loose leaf litter or beneath small stones, due to their poor ability to dig deeper nests. [31] However, if a deeper nesting ant species abandons their nest, Argentine ant colonies will readily take over the space.[ citation needed ] Because the native habitat for this species is within riparian floodplains, colonies are very sensitive to water infiltration within their nests; if their nests become inundated with water, workers will collect the brood and the entire colony will move to dry ground. [32] [33]
Austrian entomologist Gustav L. Mayr identified the first specimens of Hypoclinea humilis in the vicinity of Buenos Aires, Argentina in 1866. This species was shortly transferred to the genus Iridomyrmex , and finally to Linepithema in the early 1990s.
The native range of Argentine ants is limited to riparian habitats in the lowland areas of the Paraná River drainage, [5] [8] which stretches across northern Argentina, Uruguay, Paraguay, and southern Brazil. Within South America, this species has spread into parts of Chile, Colombia, Ecuador, and Peru. [34] Linepithema humile thrives in Mediterranean climates, and over the past century it has spread to across the globe by human-mediated transport. [5] The species has become established to every continent except Antarctica and includes many oceanic islands. [2] [35] [36]
The absence of aggression within Argentine ant colonies was first reported in 1913 by Newell & Barber, who noted "…there is no apparent antagonism between separate colonies of its own kind". [37] Later studies showed that these "supercolonies" extend across hundreds or thousands of kilometers in different parts of the introduced range, first reported in California in 2000, [35] then in Europe in 2002, [38] Japan in 2009, [39] (pp 143–147) and Australia in 2010. [13]
Several subsequent studies used genetic, behavioral, and chemical analyses to show that introduced supercolonies on separate continents actually represent a single global supercolony. [40] [39] (pp143–147)
The researchers stated that the "enormous extent of this population is paralleled only by human society", and had probably been spread and maintained by human travel. [39] (pp143–147)
They have been extraordinarily successful, in part, because different nests of the introduced Argentine ants seldom attack or compete with each other, unlike most other species of ant. In their introduced range, their genetic makeup is so uniform that individuals from one nest can mingle in a neighboring nest without being attacked. Thus, in most of their introduced range, they form supercolonies. [38] The Very Large Colony, which covers territory from San Diego to beyond San Francisco, may have a population of nearly one trillion individuals. [41] (p 204)
Conflict does occur between members of different supercolonies. In 1997, UC San Diego researchers observed fighting between different Argentine ants kept in lab, and in 2004 scientists began to map out the boundaries of the different supercolonies that clashed in San Diego. On the border of the Very Large Colony and the Lake Hodges Colony thirty million ants die each year, on a battlefront that covers many miles. While the battles of other ant species generally constitute colony raids lasting a few hours, or skirmishes that occur periodically for a few weeks, Argentine ants clash ceaselessly; the borders of their territory are a site of constant violence and battles can be fought on top of hundreds of dead ants. Fights may be halted by adverse weather such as rain. [41] (p 203–205)
In contrast, native populations are genetically more diverse and form colonies that are much smaller than the supercolonies that dominate the introduced range. Colonies living in close proximity are territorial and aggressive toward one another. Argentine ants in their native South America also co-exist with many other species of ants, and do not attain the high population densities that characterize introduced populations. [42]
In a series of experiments, ants of the same colony were isolated and fed different diets. The hydrocarbons from the diet were eventually incorporated into the cuticle of the subjects. Those that had the same diet appeared to recognize one another as kin. Those who had at least some overlap in dietary composition also appeared to react non-aggressively to one another. These interactions contrasts drastically with the groups that fed on completely different sources, such as those who lived off flies and those that fed on grasshoppers. The groups appeared to have incorporated hydrocarbons that were not similar to the others and created an unfamiliar identity cue. These groups reacted violently towards each other. This suggests that dietary factors affect the recognition cues for colony members. [43] [44]
Like workers in many other ant species, Argentine ant workers are unable to lay reproductive eggs but can direct the development of eggs into reproductive females; the production of males appears to be controlled by the amount of food available to the larvae. [45] Argentine ant colonies almost invariably have many reproductive queens, as many as eight for every 1,000 workers.
The seasonal low occurs in mid-winter, when 90% of a representative colony consists of workers and the remainder of queens, and no reproductive activity and minimal birthing. Eggs are produced in late-winter, nearly all of which hatch into sexual forms by May(*). Mating occurs after the females emerge. Worker production increases steadily from mid-March(*) to October(*), after which their numbers are not replenished; thus, their numbers drop steadily over the winter months. [31] ((*) Note that the information regarding the months May, March, and October in this paragraph, as well as the entire Month axis in the graph, are most likely not worldwide correct, in special in Southern hemisphere, due to the shift of six months in seasons between the two hemispheres.)
Colonies in the Argentine ant's native habitat are kept within a range of ten to one hundred meters by colonies of interspecific and intraspecific rivals. As the colonies expand, they appear to form fluctuating territory borders, which contract and expand on a seasonal and conditional basis. There is an expansive push outward in the summer months, with a retreating motion in the winter. This has to do with soil moisture and temperature conditions. [46] At the edges of these borders are either rival L. humile colonies or other obstacles that prevent further expansion, such as an inhospitable environment for nests. [46]
The ants are ranked among the world's 100 worst invasive animal species. [47] In its introduced range, the Argentine ant often displaces most or all native ants and can threaten native invertebrates and even small vertebrates that are not accustomed to defending against the aggressive ants. This can, in turn, imperil other species in the ecosystem, such as native plants that depend on native ants for seed dispersal, or lizards that depend on native ants or invertebrates for food. For example, the recent severe decline in coastal horned lizards in southern California is closely tied to Argentine ants displacing native ant species on which the lizards feed. [26] In South Africa, the Argentine ant has in some cases displaced native ants that disperse the seeds of Fynbos plants like Mimetes cucullatus . The Argentine ants don't take the seeds underground and are left on the surface, resulting in ungerminated plants and the dwindling of Fynbos seed reserves after veld fires. [48]
Argentine ants sometimes tend aphid, mealybug, and scale insect colonies, [49] sometimes relocating the parasites to unaffected plants, and their protection of these plant pests from predators and parasitoids can cause problems in agricultural areas. [50] In return for this protection, the ants benefit by feeding off an excretion known as "honeydew".
There is also evidence that the presence of Argentine ant may decrease the number of pollinators that visit natural flowering plants via predation on the larvae of the pollinators. [51]
Argentine ants are a common household pest, often entering structures in search of food or water (particularly during dry or hot weather), or to escape flooded nests during periods of heavy rainfall. When they invade a kitchen, it is not uncommon to see two or three queens foraging along with the workers.
Borate-sucrose water baits are toxic to Argentine ants, when the bait is 25% water, with 0.5–1.0% boric acid or borate salts. [52] [53]
In spring, during a colony's growth phase, protein based baits may be more effective due to much higher demand from the egg-laying queens. [54]
Due to their nesting behavior and presence of numerous queens in each colony, it is generally impractical to spray Argentine ants with pesticides or to use boiling water as with mound building ants. Spraying with pesticides has occasionally stimulated increased egg-laying by the queens, compounding the problem. Pest control usually requires exploiting their omnivorous dietary habits, through use of slow-acting poison bait (e.g. fipronil, hydramethylnon, sulfluramid), which will be carried back to the nest by the workers, eventually killing all the individuals, including the queens.
Researchers from the University of California, Irvine, have developed a way to use the scent of Argentine ants against them. [55] The exoskeletons of the ants are covered with a hydrocarbon-laced secretion. They made a compound that is different, but similar, to the one that coats the ants. If the chemical is applied to an ant, the other members of the colony will kill it. [56]
Another approach for a large scale control of the Argentine ant has been proposed by researchers from Japan, who showed that it is possible to disrupt its trails with synthetic pheromones. [57] This has been confirmed in various later trials by a New Zealand-led team in Hawaii [58] and by researchers from Victoria University of Wellington who showed that this approach is beneficial for other local ant species. [59]
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 22,000 species have been classified. They are easily identified by their geniculate (elbowed) antennae and the distinctive node-like structure that forms their slender waists.
The yellow crazy ant, also known as the long-legged ant or Maldive ant, is a species of ant, thought to be native to West Africa or Asia. They have been accidentally introduced to numerous places in the world's tropics.
Solenopsis invicta, the fire ant, or red imported fire ant (RIFA), is a species of ant native to South America. A member of the genus Solenopsis in the subfamily Myrmicinae, it was described by Swiss entomologist Felix Santschi as a variant of S. saevissima in 1916. Its current specific name invicta was given to the ant in 1972 as a separate species. However, the variant and species were the same ant, and the name was preserved due to its wide use. Though South American in origin, the red imported fire ant has been accidentally introduced in Australia, New Zealand, several Asian and Caribbean countries, Europe and the United States. The red imported fire ant is polymorphic, as workers appear in different shapes and sizes. The ant's colours are red and somewhat yellowish with a brown or black gaster, but males are completely black. Red imported fire ants are dominant in altered areas and live in a wide variety of habitats. They can be found in rainforests, disturbed areas, deserts, grasslands, alongside roads and buildings, and in electrical equipment. Colonies form large mounds constructed from soil with no visible entrances because foraging tunnels are built and workers emerge far away from the nest.
An ant colony is a population of ants, typically from a single species, capable of maintaining their complete lifecycle. Ant colonies are eusocial, communal, and efficiently organized and are very much like those found in other social Hymenoptera, though the various groups of these developed sociality independently through convergent evolution. The typical colony consists of one or more egg-laying queens, numerous sterile females and, seasonally, many winged sexual males and females. In order to establish new colonies, ants undertake flights that occur at species-characteristic times of the day. Swarms of the winged sexuals depart the nest in search of other nests. The males die shortly thereafter, along with most of the females. A small percentage of the females survive to initiate new nests.
Tapinoma sessile is a species of small ant that goes by the common names odorous house ant, sugar ant, stink ant, and coconut ant. Their colonies are polydomous and polygynous. Like many social insects, T. sessile employs complex foraging strategies, allocates food depending on environmental conditions, and engages in competition with other insects.
Deborah M. Gordon is an American biologist best known for her impactful research in the behavioral ecology of ants and her studies on the operations of ant colonies without a central control. In addition to overseeing The Gordon Lab, she is currently a Professor of Biology at Stanford University.
Iridomyrmex is a genus of ants called rainbow ants first described by Austrian entomologist Gustav Mayr in 1862. He placed the genus in the subfamily Dolichoderinae of the family Formicidae. It has 79 described species and five fossil species. Most of these ants are native to Australia; others are found in Asia and Oceania, and they have been introduced to Brazil, New Zealand, and the United Arab Emirates. Fossil species are known from China, France, and the United States.
The meat ant, also known as the gravel ant or southern meat ant, is a species of ant endemic to Australia. A member of the genus Iridomyrmex in the subfamily Dolichoderinae, it was described by British entomologist Frederick Smith in 1858. The meat ant is associated with many common names due to its appearance, nest-building behaviour and abundance, of which its specific name, purpureus, refers to its coloured appearance. It is among the best-known species of ant found throughout Australia; it occurs in almost all states and territories except for Tasmania. Its enormous distribution, aggression and ecological importance have made this ant a dominant species.
Pogonomyrmex occidentalis, or the western harvester ant, is a species of ant that inhabits the deserts and arid grasslands of the American West at or below 6,300 feet (1,900 m). Like other harvester ants in the genus Pogonomyrmex, it is so called because of its habit of collecting edible seeds and other food items. The specific epithet "occidentalis", meaning "of the west", refers to the fact that it is characteristic of the interior of the Western United States; its mounds of gravel, surrounded by areas denuded of plant life, are a conspicuous feature of rangeland. When numerous, they may cause such loss of grazing plants and seeds, as to constitute both a severe ecological and economic burden. They have a painful and venomous sting.
Ochetellus is a genus of ants first described by Steve Shattuck in 1992. He placed it in the subfamily Dolichoderinae of the family Formicidae. The ants in this genus are small and black in colour; workers measure 1.75 to 3 millimetres in length, the males at around 1.6 millimetres (0.06 in) are smaller, and the queens are the largest, reaching 4 millimetres (0.16 in). There are seven described species and three described subspecies that mostly live in Australia in a wide variety of habitats, but some species are found in Asia. One species, Ochetellus glaber, has been introduced into New Zealand and the United States.
Trichomyrmex destructor is a species of ant in the subfamily Myrmicinae. Its common names include destructive trailing ant or Singapore ant. It is a pest species in urban areas, known for causing costly damage to structures, vehicles, and electronic devices with its chewing activity. In 2015, the species was moved from the genus Monomorium to the revised genus Trichomyrmex.
Linepithema fuscum is a species of ant in the genus Linepithema. Described by Mayr in 1866, the species is endemic to South America. Linepithema fucsum was the first species-level name assigned to genus Linepithema by Mayr. It is related to L. angulatum, L. keiteli, L. piliferum and L. tsachila. However, only Linepithema fuscum remains without a worker association and it could be possible that males of Linepithema fuscum actually belong to the workers of L. angulatum. Little is known about Linepithema fuscum due to the scarcity of the collected samples.
Linepithema micans is a small species of ant from the genus Linepithema which was described by Auguste-Henri Forel in 1908. This ant is endemic to southern South America. In Brazil, it is considered a pest of vineyards in acting as the main species associated with the coccid Eurhizococcus brasiliensis. It is still a poorly studied species. Their abundant larvae are round and whitish, almost indistinguishable from the proximate species Linepithema humile, better known as the invasive Argentine ant.
This is a glossary of terms used in the descriptions of ants.
Brachymyrmex patagonicus, also known as the black rover ant, is a species of Formicine ant native to Mexico, Central America, South America, and invasive in the United States and Europe. They were first reported in St. Tammany Parish, Louisiana in 1978 from a single colony collected in 1976. It is believed that the species was introduced through New Orleans, which is a common entry point for many tropical species, but other locations such as Mobile, Alabama, or Pensacola, Florida, are also likely. For many years B. patagonicus, B. musculus, and B. obscurior were misidentified as being separate species but after a comparison of specimens from the Louisiana State University Arthropod Collection (LSUC), it was found that all three were the same species. B. patagonicus is considered a nuisance pest due to their tendency to infest man-made structures but have received a lack of attention because they do not bite, sting, or carry disease.
Camponotus dumetorum is a species of carpenter ant native to North America. They are related to other species from the subgenus Tanaemyrmex in western North America such as C. semitestaceus and C. vicinus. C. dumetorum are primarily nocturnal and form nests underground. Like other select ant species native to California, their populations have been displaced with the introduction of Argentine ants.
The social networks of colonies of social insects have been extensively studied as model biological networks.
In ecology, a tramp species is an organism that has been spread globally by human activities. The term was coined by William Morton Wheeler in the bulletin of the American Museum of Natural History in 1906, used to describe ants that “have made their way as well known tramps or stow-aways [sic] to many islands". The term has since widened to include non-ant organisms, but remains most popular in myrmecology. Tramp species have been noted in multiple phyla spanning both animal and plant kingdoms, including but not limited to arthropods, mollusca, bryophytes, and pteridophytes. The term "tramp species" was popularized and given a more set definition by Luc Passera in his chapter of David F William's 1994 book Exotic Ants: Biology, Impact, And Control Of Introduced Species.
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