''Iridomyrmex'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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 ...

s called rainbow ants (referring to their blue-green iridescent sheen) first described by Austrian entomologist

Gustav Mayr Gustav L. Mayr (12 October 1830 – 14 July 1908) was an Austrian entomologist and professor in Budapest and Vienna. He specialised in Hymenoptera, being particularly known for his studies of ants.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 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 ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

, and the

United Arab Emirates The United Arab Emirates (UAE; ar, اَلْإِمَارَات الْعَرَبِيَة الْمُتَحِدَة ), or simply the Emirates ( ar, الِْإمَارَات ), is a country in Western Asia ( The Middle East). It is located at t ...

. Fossil species are known from China, France, and the United States. These ants are known to be an ecologically dominant and important group of ants, but they are sometimes regarded as pests because they disturb soil and enter human houses. Farmers in rural Australia place animal carcasses on meat ant ('' I. purpureus'') mounds as a method of disposing of them; meat ants consume the carcass and reduce it to bones in a matter of weeks. Meat ants also engage in ritualised fighting, which helps prevent casualties and solve territorial disputes between neighbouring colonies. The largest members of this genus are those of the ''I. purpureus'' species group, measuring . After their

nuptial flight Nuptial flight is an important phase in the reproduction of most ant, termite, and some bee species. It is also observed in some fly species, such as '' Rhamphomyia longicauda''. During the flight, virgin queens mate with males and then land t ...

, queen ants may establish a colony by themselves, by budding, or cooperatively, where a subset of the colony migrates to a new location or when multiple queens help find a suitable nesting spot, but they display intolerance to each other when workers are present. The eggs take 44 to 61 days to fully develop into adults. Ants of the genus live in a wide variety of habitats and nest in soil in numbers that range from a few hundred individuals to over 300,000 in a single colony. Depending on the species, nests are large mounds covered in pebbles with multiple entrances, while others live above ground in twig nests. In some cases, ants dwell in several nest sites connected by paths; some of these nests can extend to in length. Some species associate with caterpillars and butterflies that provide the ants with secretions and honeydew, and '' I. bicknelli'' pollinates

orchids Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of flowering ...

. These ants are predators and scavengers; they hunt for prey to feed their young. Notably, these ants are immune to the toxins of the

cane toad The cane toad (''Rhinella marina''), also known as the giant neotropical toad or marine toad, is a large, terrestrial true toad native to South and mainland Central America, but which has been introduced to various islands throughout Oceania ...

and feed on the juveniles. Predators such as spiders, birds, lizards, and other ants prey on ''Iridomyrmex'' ants.

Phylogeny

The separation of the genus ''Iridomyrmex'' from its most recent common ancestor began around 12 million years ago. Its sister group, '' Froggattella'', has only two species, even though both genera are the same age. In comparison to other Indo-Australian genera in the subfamily Dolichoderinae, the clade of which it is a part, is 23 million years old, meaning that it is rather young. However, the fossil species that have been found are from the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

and Oligocene. The following

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

shows the phylogenetic position of ''Iridomyrmex'' among the Indo-Australian genera:

Taxonomy

The genus ''Iridomyrmex'' was first described by Austrian entomologist

Gustav Mayr Gustav L. Mayr (12 October 1830 – 14 July 1908) was an Austrian entomologist and professor in Budapest and Vienna. He specialised in Hymenoptera, being particularly known for his studies of ants.type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

until 1903. By then, the type species was designated as ''Formica detecta'', a synonym of ''

Iridomyrmex purpureus ''Iridomyrmex'' is a genus of ants called rainbow ants (referring to their blue-green iridescent sheen) first described by Austrian entomologist Gustav Mayr in 1862. He placed the genus in the subfamily Dolichoderinae of the family Formicida ...

''. The genus was placed in the subfamily Dolichoderinae in 1878, the same year the subfamily was established. Since the establishment of the genus, it suffered taxonomic misunderstanding due to the gradual development of unrelated ants being designated into the genus by early researchers who failed to identify easily recognisable features that would make them distinct from the genus ''Iridomyrmex''. Myrmecologist William Brown, Jr., was perhaps the first person to question the monophyly of the genus, mentioning that the

Argentine ant The Argentine ant (''Linepithema humile''), formerly ''Iridomyrmex humilis'', is an ant native to northern Argentina, Uruguay, Paraguay, Bolivia and southern Brazil. It is an invasive species that has been established in many Mediterranean c ...

, a former member of ''Iridomyrmex'', differed from the rest of the genus. The first proper revisions of the genus began in the 1990s, and 91 species were transferred to six genera; only 62 species remained after these revisions. These species were placed into the genera '' Anonychomyrma'', '' Doleromyrma'', '' Linepithema'', '' Ochetellus'', '' Papyrius'' and '' Philidris''. In 2011, the genus was revised again, and 79 species and five extinct species were now present, 31 of which were newly described. Four species were placed in different genera while 25 species and subspecies were classified as synonyms. According to one source, 350 Australian ''Iridomyrmex'' species may be present. The scientific name of the genus, ''Iridomyrmex'', meaning "rainbow ant", refers to their blue-green iridescent sheen. The word ''Irido'', meaning "rainbow", derives from

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

, and ''myrmex'', another Greek word, means "ant".

Species

xtinct species are marked with † *'' Iridomyrmex adstringatus'' Heterick & Shattuck, 2011 *'' Iridomyrmex agilis'' Forel, 1907 *'' Iridomyrmex alpinus'' Heterick & Shattuck, 2011 *'' Iridomyrmex anceps'' (Roger, 1863) *'' Iridomyrmex anderseni'' Shattuck, 1993 *'' Iridomyrmex angusticeps'' Forel, 1901 *'' Iridomyrmex anteroinclinus'' Shattuck, 1993 *'' Iridomyrmex atypicus'' Heterick & Shattuck, 2011 *'' Iridomyrmex azureus'' Viehmeyer, 1914 *'' Iridomyrmex bicknelli'' Emery, 1898 *'' Iridomyrmex bigi'' Shattuck, 1993 *'' Iridomyrmex brennani'' Heterick & Shattuck, 2011 *†'' Iridomyrmex breviantennis'' Théobald, 1937 *'' Iridomyrmex brunneus'' Forel, 1902 *'' Iridomyrmex calvus'' Emery, 1914 *'' Iridomyrmex cappoinclinus'' Shattuck, 1993 *'' Iridomyrmex cephaloinclinus'' Shattuck, 1993 *'' Iridomyrmex chasei'' Forel, 1902 *'' Iridomyrmex coeruleus'' Heterick & Shattuck, 2011 *''

Iridomyrmex conifer ''Iridomyrmex conifer'' is a species of ant in the genus ''Iridomyrmex''. Endemic to Australia, it was described by Auguste-Henri Forel Auguste-Henri Forel (1 September 1848 – 27 July 1931) was a Swiss myrmecologist, neuroanatomist, psychia ...

'' Forel, 1902 *'' Iridomyrmex continentis'' Forel, 1907 *'' Iridomyrmex cuneiceps'' Heterick & Shattuck, 2011 *'' Iridomyrmex cupreus'' Heterick & Shattuck, 2011 *'' Iridomyrmex curvifrons'' Heterick & Shattuck, 2011 *'' Iridomyrmex cyaneus'' Wheeler, 1915 *'' Iridomyrmex difficilis'' Heterick & Shattuck, 2011 *'' Iridomyrmex discors'' Forel, 1902 *'' Iridomyrmex dromus'' Clark, 1938 *'' Iridomyrmex elongatus'' Heterick & Shattuck, 2011 *'' Iridomyrmex exsanguis'' Forel, 1907 *†'' Iridomyrmex florissantius'' Carpenter, 1930 *''

Iridomyrmex fulgens ''Iridomyrmex fulgens'' is a species of ant in the genus ''Iridomyrmex''. Described by Heterick and Shattuck in 2011, the species is found in several states in Australia, usually in the drier regions of the country. Etymology The species name d ...

'' Heterick & Shattuck, 2011 *'' Iridomyrmex galbanus'' Shattuck, 1993 *'' Iridomyrmex gibbus'' Heterick & Shattuck, 2011 *'' Iridomyrmex gumnos'' Heterick & Shattuck, 2011 *'' Iridomyrmex hartmeyeri'' Forel, 1907 *'' Iridomyrmex hertogi'' Heterick & Shattuck, 2011 *'' Iridomyrmex hesperus'' Shattuck, 1993 *'' Iridomyrmex infuscus'' Heterick & Shattuck, 2011 *'' Iridomyrmex innocens'' Forel, 1907 *'' Iridomyrmex lividus'' Shattuck, 1993 *'' Iridomyrmex longisoma'' Heterick & Shattuck, 2011 *'' Iridomyrmex luteoclypeatus'' Heterick & Shattuck, 2011 *'' Iridomyrmex macrops'' Heterick & Shattuck, 2011 *†'' Iridomyrmex mapesi'' Wilson, 1985 *'' Iridomyrmex mattiroloi'' Emery, 1898 *'' Iridomyrmex mayri'' Forel, 1915 *'' Iridomyrmex meridianus'' Heterick & Shattuck, 2011 *'' Iridomyrmex minor'' Forel, 1915 *'' Iridomyrmex mirabilis'' Heterick & Shattuck, 2011 *'' Iridomyrmex mjobergi'' Forel, 1915 *'' Iridomyrmex neocaledonica'' Heterick & Shattuck, 2011 *'' Iridomyrmex niger'' Heterick & Shattuck, 2011 *'' Iridomyrmex nudipes'' Heterick & Shattuck, 2011 *†'' Iridomyrmex obscurans'' Carpenter, 1930 *'' Iridomyrmex obscurior'' Forel, 1902 *'' Iridomyrmex obsidianus'' Emery, 1914 *'' Iridomyrmex omalonotus'' Heterick & Shattuck, 2011 *'' Iridomyrmex pallidus'' Forel, 1901 *'' Iridomyrmex phillipensis'' Heterick & Shattuck, 2011 *'' Iridomyrmex prismatis'' Shattuck, 1993 *''

'' (Smith, 1858) *'' Iridomyrmex reburrus'' Shattuck, 1993 *'' Iridomyrmex roseatus'' Heterick & Shattuck, 2011 *'' Iridomyrmex rubriceps'' Forel, 1902 *'' Iridomyrmex rufoinclinus'' Shattuck, 1993 *''

Iridomyrmex rufoniger ''Iridomyrmex rufoniger'' is a species of ant in the genus ''Iridomyrmex''. It was described by Lowne in 1865. The species is endemic to Australia and introduced to several other countries. Taxonomy The species was first described by Lowne in 18 ...

'' (Lowne, 1865) *'' Iridomyrmex sanguineus'' Forel, 1910 *'' Iridomyrmex setoconus'' Shattuck & McMillan, 1998 *†'' Iridomyrmex shandongicus'' Zhang, 1989 *'' Iridomyrmex spadius'' Shattuck, 1993 *'' Iridomyrmex splendens'' Forel, 1907 *'' Iridomyrmex spodipilus'' Shattuck, 1993 *'' Iridomyrmex spurcus'' Wheeler, 1915 *'' Iridomyrmex suchieri'' Forel, 1907 *'' Iridomyrmex suchieroides'' Heterick & Shattuck, 2011 *'' Iridomyrmex tenebrans'' Heterick & Shattuck, 2011 *'' Iridomyrmex tenuiceps'' Heterick & Shattuck, 2011 *'' Iridomyrmex trigonoceps'' Heterick & Shattuck, 2011 *'' Iridomyrmex turbineus'' Shattuck & McMillan, 1998 *'' Iridomyrmex victorianus'' Forel, 1902 *'' Iridomyrmex viridiaeneus'' Viehmeyer, 1914 *'' Iridomyrmex viridigaster'' Clark, 1941 *'' Iridomyrmex xanthocoxa'' Heterick & Shattuck, 2011

Description

Unlike other genera in Dolichoderinae, the front margin of the clypeus is not below the

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

s; instead, it is located above them. The

eyes Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and con ...

are located on top of the ants' head, and they are noticeably distant from the mandibles. These ants range from small to medium; members of the ''I. conifer'' species group measure , being reddish-brown in colour with a distinctive propodeum, while members of the ''I. purpureus'' species group are the largest at . Worker castes are rarely polymorphic. Based on observations, ''Iridomyrmex'' workers can be deformed when they are born. For example, a captured specimen had its propodeum and gaster fused together, and the petiole was still present but enlarged. Despite the deformity, the worker was still able to forage with little trouble.

Distribution and habitat

Ants of this genus are found in a range spanning several continents. In the Oceanian region, these ants are found in Fiji,

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

, New Caledonia,

Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...

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 ...

. In Australia, they are found in every state and territory. In

, this genus has been introduced to the country, establishing themselves in both the North Island and South Island. In

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

, they are found in

Burma Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...

East Timor East Timor (), also known as Timor-Leste (), officially the Democratic Republic of Timor-Leste, is an island country in Southeast Asia. It comprises the eastern half of the island of Timor, the exclave of Oecusse on the island's north-west ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

and the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

. '' I. anceps'' is the only known ant of this genus present in the

Middle East The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabia (including the Arabian Peninsula and Bahrain), Asia Minor (Asian part of Turkey except Hatay Province), East Thrace (Europ ...

, having been introduced to the

. '' I. rufoniger'' was introduced to

through human activity. Populations are present on the islands of Norfolk Island and

Phillip Island Phillip Island ( Boonwurrung: ''Corriong'', ''Worne'' or ''Millowl'') is an Australian island about south-southeast of Melbourne, Victoria. The island is named after Governor Arthur Phillip, the first Governor of New South Wales, by explore ...

Oceania Oceania (, , ) is a geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern and Western hemispheres, Oceania is estimated to have a land area of and a population of around 44.5 million ...

. Extinct species were native to a range spanning beyond the modern distribution of the genus; fossils have been found in China,

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

and the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

. The genus ''Iridomyrmex'' inhabits rural, arid, and

semi-arid A semi-arid climate, semi-desert climate, or steppe climate is a dry climate sub-type. It is located on regions that receive precipitation below potential evapotranspiration, but not as low as a desert climate. There are different kinds of semi- ...

areas. Nests are found in '' Acacia'', '' Agathis'', ''

Banksia ''Banksia'' is a genus of around 170 species in the plant family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes, and fruiting "cones" and heads. ''Banksias'' range ...

'', '' Casuarina'' and ''

Eucalyptus ''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including '' Corymbia'', they are commonly known as e ...

'' woodland, in pastures, '' Callitris'' forests, city parks, farmlands, grasslands,

heath A heath () is a shrubland habitat found mainly on free-draining infertile, acidic soils and characterised by open, low-growing woody vegetation. Moorland is generally related to high-ground heaths with—especially in Great Britain—a cooler a ...

, sand dunes, savanna woodland, swamps, urban gardens, wet rain-forests, wet and dry sclerophyll woodland, and even in buildings such as hotels and houses. Most of these ants nest in soil, but some prefer to live under rocks, rotten wood, and in some cases in sandy beaches and footpaths. Certain species will avoid nesting in sandy soil. Nests will vary in appearance; most species live in small mounds with a single entrance, while other species create large mounds covered in pebbles with multiple entrances. Some colonies are known to create "super-nests": workers construct many nests connected through established paths, extending up to in length. In one extreme case, a single colony was found to occupy over 10 hectares of land with 85 individual nests and 1,500 entrance holes. While meat ants are never aggressive to their nest mates, they will be aggressive to those who live in different nests within the same colony. Nests may be above or below ground, with some species such as '' I. conifer'' alternating between the two; during winter, nests will be constructed above in twigs, with the ants moving back underground during the warmer months. Underground nests are located near areas where food sources are present. Colonies will relocate their nests to areas where there are reasonable levels of sunlight during winter.

Behaviour and ecology

Most ''Iridomyrmex'' species are aggressive ants that will attack anything which attacks or disturbs their nests or trails they forage on. This is noticeable with particular member species of the ''I. purpureus'' species group, where they will pour out of their nest and attack and kill all intruders. Even smaller species show similar behaviours to these ants and will also swarm out of their nests to bite and spray

iridomyrmecin Iridomyrmecin is a defensive chemical, classified as an iridoid, isolated from ants of the genus ''Iridomyrmex''. It has also evolved into a sex pheromone in wasps such as ''Leptopilina'', with host species using the smell of iridomyrmecin as a wa ...

, a defensive chemical found in the genus. Because of their large numbers, aggression, and activeness, ''Iridomyrmex'' ants are ecologically dominant in Australia, and several species are known to obtain exclusive possession to food sources and prevent other insects from using them. These ants will also affect foraging behaviours of other ant nests living nearby due to how active they are and their large numbers. While ''Iridomyrmex'' ants are known for their aggression, some are more timid and shy; workers will run and hide if they are disturbed and avoid contact with other ant species. When nests are disturbed, workers will not attack; instead, they will relocate their brood and disregard other disturbances should they occur. Workers will hide in leaves and other vegetation, and in some cases, ''I. victorianus'' workers may remain still until any threat or danger subsides. Meat ants engage in ritualised fights to maintain and resolve boundary disputes with neighbouring colonies. When individuals from separate colonies meet, they will engage each other until appeasement occurs. A meat ant detects a foreign worker by intense antennation and gaping of the mandibles, and will also stretch themselves upward to appear taller and larger, suggesting that meat ants do this in a display of size matching. Once the ants have finished fighting, they will groom themselves and search for another ant. Such disputes between colonies may continue for months or even years in the same area, and escalated fights that result in serious injury or death are rare.

Foraging

All species are predators and scavengers. ''Iridomyrmex'' ants tend to many Hemiptera insects and butterfly larvae to receive honeydew. Workers forage and scavenge for small insects, and they collect nectar from flowers and hunt for prey. ''Iridomyrmex'' ants normally forage on the ground, but most species will forage up into trees and vegetation to look for food. Most ants are diurnal foragers, but some are nocturnal. These nocturnal ants will sometimes become active during the day, but this depends on the suitability of the weather. They will also block their entrance holes when it is daytime; however, '' I. bigi'' is nocturnal and never comes out during the day. In a few species, a nest will not be placed in a shaded area; this is so it can warm up during the early mornings and workers can forage shortly after sunrise.

Diet

Shattuck 45354-1, ANIC32-042205, Iridomyrmex, Darwin, NT

''Iridomyrmex'' primarily feeds on sweet foods such as nectar and honeydew. They hunt for insects and other ants to feed to their young, and workers are particularly attracted to seeds with elaiosomes. They collect these seeds, remove the elaiosomes, and then discard the seeds. The seedlings that sprout from these seeds benefit from proximity to the aggressive ''Iridomyrmex'' ants, giving them a better chance of survival. Colonies sometimes nest in termite mounds, and so the termites are regularly preyed on by ''Iridomyrmex''; no evidence for any kind of relationship (other than a predatory one) is known. Juvenile cane toads are often preyed on, as certain ''Iridomyrmex'' species such as ''I. purpureus'' and ''I. ruburrus'' are immune to the toxins released by the cane toads. As a result, placing ''Iridomyrmex'' nests in habitats which house cane toads have been suggested as a method of controlling the cane toad population. The meat ant is the only known ant in Australia that feeds on guano.

Predators

Some invertebrate species specialise in predation of ''Iridomyrmex'' ants. One spider in particular, the cursorial spider '' Habronestes bradleyi'', is a specialist predator against these ants and will use the alarm pheromones that are released by the ants during territorial disputes to locate them. The Australian thorny devil lizard (''Moloch horridus'') is a sit and wait predator that primarily preys on ''Iridomyrmex'' ants, and one lizard will reject specific species in this genus while eating others. The blind snake '' Ramphotyphlops nigrescens'' follows trails laid by these ants to locate them as a potential prey species and will eat the broods of some species, while ground beetles dig burrows near ant nests to prey on workers passing by. A prominent predator is the

short-beaked echidna The short-beaked echidna (''Tachyglossus aculeatus''), also called the short-nosed echidna, is one of four living species of echidna and the only member of the genus ''Tachyglossus''. It is covered in fur and spines and has a distinctive snout ...

(''Tachyglossus aculeatus'') that eats the virgin queens during nuptial flight due to their high percentage of fat. Echidnas do not consume ''Iridomyrmex'' ants all year; instead, they usually attack nests during August to October, which is when the winged females and males, known as

alate Alate (Latin ''ālātus'', from ''āla'' (“wing”)) is an adjective and noun used in entomology and botany to refer to something that has wings or winglike structures. In entomology In entomology, "alate" usually refers to the winged form o ...

s emerge from their nest. Queens will also face more threats during nuptial flight or after; birds such as

currawong Currawongs are three species of medium-sized passerine birds belonging to the genus ''Strepera'' in the family Artamidae native to Australia. These are the grey currawong (''Strepera versicolor''), pied currawong (''S. graculina''), and black ...

magpies Magpies are birds of the Corvidae family. Like other members of their family, they are widely considered to be intelligent creatures. The Eurasian magpie, for instance, is thought to rank among the world's most intelligent creatures, and is one ...

and

ravens Ravens may refer to: * Raven, a species of the genus ''Corvus'' Sports * Anderson Ravens, the intercollegiate athletic program of Anderson University in Indiana * Baltimore Ravens, a professional American football franchise * Benedictine Ravens, ...

, attracted by recently excavated soil, will dig out nests shortly after the queens have founded their colonies. Parasitic flatworms in the class Cestoda are known to infect ''Iridomyrmex''.

Life cycle and reproduction

Nuptial flight occurs throughout the year in humid and warm climates. The alates begin to emerge from their nest and immediately climb onto tall structures (such as tree trunks, fence-posts, or long flora) where they begin to fly and copulate. Depending on the species, a queen either mates with a single male or with multiple males. Observations show that meat ant males begin to fly first, followed by the queens. Groups of 20 to 40 queens will approach the top of the nest and fly once they are warm enough, and this would proceed multiple times for many days until the climate changes or all of the queens have withdrawn from the nest. After mating, the males soon die and the queens proceed to search for a suitable nest to establish her colony. Finding a location to nest is dangerous, as birds and other ants prey on them; disease and starvation are other causes of death in queens. While most queens will establish a nest by herself, nests can be established when queens cooperate with each other, are adopted into an existing colony, or by "budding" (also called "satelliting" or "fractionating"), where a subset of the colony including queens, workers and brood (eggs, larvae and pupae) leave the main colony for an alternative nest site. 10% of queens will cooperate with another queen during colony foundation. Once a queen has excavated a chamber, she will lay around 20 eggs that develop into larvae in less than a month. These eggs take 44 to 61 days to fully develop and emerge as adults. Mature nests range in size, from a few hundred to over 300,000 workers. Most colonies are monogyne, meaning it only has a single queen, but some colonies can have as many as four. Oligogynous colonies also exist, in which multiple queens are present, but they are tolerated equally by workers birthed from different mothers and antagonism exists among queens. Brood discrimination is known based on recognition of kin, and queens will look after their own brood and neglect other brood laid by different queens. Queens display intolerance to each other when the first generation of workers is present, and the queens will separate from each other once the colony grows to a certain size.

Symbiosis

Shattuck 49466-2, Iridomyrmex septentrionalis visiting scale, Hall, ACT

''Iridomyrmex'' ants share symbiotic relationships with many

caterpillars Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Symp ...

aphids 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 ...

and coccids. Workers protect these caterpillars and will sometimes take them to their feeding chambers inside the nest. In the genus '' Jalmenus'', workers attend to the butterflies '' Jalmenus clementi'' (turquoise hairstreak), '' Jalmenus daemeli'' (emerald hairstreak), '' Jalmenus eichhorni'' (northern hairstreak),'' Jalmenus evagoras'' (imperial hairstreak) '' Jalmenus icilius'' (amethyst hairstreak), '' Jalmenus inous'' (varied hairstreak) and '' Jalmenus lithochroa'' (Waterhouse's hairstreak). In the genus '' Ogyris'', attendants include '' Ogyris amaryllis'' (satin azure), '' Ogyris olane'' (olane azure) and '' Ogyris oroetes'' (silky azure). Additional species workers attend include '' Anthene lycaenoides'' (pale ciliate blue), '' Candalides heathi'' (rayed blue), '' Candalides margarita'' (trident pencil-blue), '' Deudorix diovis'' (bright cornelian), '' Euchrysops cnejus'' (gram blue), '' Lampides boeticus'' (pea blue), ''

Leptotes plinius ''Leptotes plinius'', the zebra blue or plumbago blue, is a species of blue butterfly (Lycaenidae) found in Sri Lanka, India to Australia. The species was first described by Johan Christian Fabricius in 1793. Description This form closely ...

'' (plumbago blue), '' Lucia limbaria'' (chequered copper), '' Nesolycaena caesia'' (Kimberly spotted opal), '' Neolucia agricola'' (fringed heath-blue) and '' Theclinesthes serpentata'' (saltbush blue). ''I. bicknelli'' is an effective pollinator of '' Microtis parviflora'', and one study suggests the pollen is not harmed by contact of these ants. Meat ants have been observed blocking banded sugar ant nesting holes with pebbles and soil to prevent them from leaving their nest during the early hours of the day. The ants counter this by preventing meat ants from leaving their nest by blocking their nesting holes with debris, a behaviour known as nest-plugging. If meat ant nests are encroached by trees or other shade, banded sugar ants may invade and take over the nest, since the health of the colony may deteriorate from overshadowing. Members of an affected meat ant colony later move to a nearby satellite nest that is placed in a suitable area, while invading banded sugar ants fill nest galleries up with a black resinous material.

Interaction with humans

In rural Australia, meat ants are important to farmers as they place animal carcasses on their nests. In a matter of weeks, the entire carcass will be consumed and reduced to bones. However, ''Iridomyrmex'' ants are sometimes considered pests, due to these ants entering human houses to feed on food and soil disturbance. Eradication of nests can be difficult, as nests can be repopulated from a rival colony or adjoining nests which were not affected. Particular species have adapted rather well to urbanisation; during the early days in Canberra, newly constructed suburbs provided new nest sites for meat ants, and populations flourished. Other factors include plantations enriched with valuable food sources and home gardens. Workers also cause problems for those who are ''

Citrus ''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, lemons, grapefruits, pomelos, and limes. The genus ''Citrus'' is native to ...

'' producers; they will affect the biological control of Hemiptera insects, specifically those who produce honeydew.

References

Cited texts

External links

* *
''Iridomyrmex'' at the AntWiki – Bringing Ants to the World
{{Taxonbar, from=Q141460 Ant genera Hymenoptera of Asia Hymenoptera of Australia Hymenoptera of South America Household pest insects Taxa named by Gustav Mayr

Phylogeny

Taxonomy

Species

Description

Distribution and habitat

Behaviour and ecology

Foraging

Diet

Predators

Life cycle and reproduction

Symbiosis

Interaction with humans

See also

References

Cited texts

External links