Acromyrmex striatus

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Acromyrmex striatus
Acromyrmex striatus casent0104326 profile 1.jpg
A. striatus worker
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Genus: Acromyrmex
Species:
A. striatus
Binomial name
Acromyrmex striatus
Roger, 1863 [1]

Acromyrmex striatus is a species of the leaf-cutter ants found in the Neotropics. [2]

Contents

It is a member of the subfamily Myrmicinae, and within the tribe Attini. As an attine, Acromyrmex striatus forages for vegetation that will be applied to the fungal garden, typical in all leaf-cutting species. [3] The fungus is fed the mycophagous larvae [4] and queen, while workers are nourished primarily by the sap of cut plants, and very little by the mutualistic fungus making them respectively, phytophagous, and mycophagous. [3] The presence of leaf-cutter ants is so common in the Neotropics, that they are considered to be the main herbivores of these areas., [2] [4]

A. striatus is a polymorphic species, meaning that there are several different sizes of workers, with the largest being 6.5 mm long. [3] This is done to compartmentalize a variety of tasks so they can be done efficiently.

Distribution

A. striatus is most commonly found in the southern states of Santa Catarina and Rio Grande do Sul in Brazil, and also the countries of Argentina, Uruguay, and Paraguay. At least in Argentina, it prefers nest sites in arid and semi-arid areas, where the sun can shine on it all year. [5]

Foraging

A. striatus is an opportunistic forager, [3] [6] collecting material from all available sources. [4] These ants may cut directly from plants, they may scavenge materials that have already fallen, or they may even collect feces or carcasses of other arthropods. [3] In fact, researchers have found that at least 53 different species of plants are collected by A. striatus, from 23 families, the majority being Compositae, Gramineae, and Leguminosae. [3] However, in terms of foraging area, A. striatus generally keep to grasses and shrubs., [5] [3] Foraging takes place only on days with a temperature of greater than 20 °C., [5] [6] This means that in more temperate climates, foraging is restricted to a few hours a day, and only during summer. [5] It has been documented that A. striatus demonstrates a "resource conservation strategy", [3] which theorizes that workers will choose to forage farther away from the nest to avoid overexploitation of resources closer to home. [3] This would result in target resources having a chance to regrow before being collected again. It has been hypothesized that the driving force behind this behavior is that the ants are concerned with obtaining high quality materials. [3] It seems that A. striatus is accomplished at providing its mutualistic fungus with a steady and predictable supply of nourishment. [3] This can be proven in one study, for it shows that the ant uses similar amounts of a multitude of plant species throughout the year. [3]

Farmers may find themselves competing with A. striatus if the vegetation present in an area is intended for human consumption., [3] [7] Foraging methods may be prevented in a variety of ways, but in terms of natural control, it seems that the ant Camponotus blandus (a non-leaf-cutting species) deters A. striatus from foraging on the shrubs where it collects nectar. [8]

Nests

Nests can be found primarily in the open, where the sun can shine on them regularly and directly. [5] [3] The ground is cleared by the workers around the opening. [3]

In order to prevent the spread of fires in South America, firebreaks have been implemented. Curiously, A. striatus favor these areas. [9] Ant nests are carefully regulated to maintain stable conditions in humidity, moisture, temperature, carbon dioxide levels, and many other factors. [9] When humans dig up the ground, the soil is more porous, which allows for better gas exchange and water infiltration, aiding the fungal gardens. [9] Indeed, not just in firebreaks but any anthropogenic modification of the soil, including roadsides. [9] These favorable conditions for A. striatus result in a competitive advantage over other species of ant, and may result in increased damage to nearby plant materials. [9]

Nuptial flights

Many species of ant disperse a large amount of sexual individuals in the air at once, synchronized with other colonies of the same species. This increases the mixing of individuals from different colonies, and therefore inhibits genetic instability through inbreeding. While in A. striatus, few individuals participate in nuptial flights, increasing the likelihood of mating with related individuals. [10] Also, breeding time is extended over a period of months, not weeks. [10] Sexual individuals are produced from October to January, [11] with small numbers of individuals departing the nest every day [12] while it is sunny. [11] Therefore, polyandry, which is the behavior of multiple fathers contributing their sperm, plays an important role in maintaining genetic diversity. [10] We can see evidence of this theory in reality as there are more males than females on average in A. striatus nuptial flights. [11]

Social hierarchy and genetics

Acromyrmex is the most complex taxon of the family Formicidae. [7] Complexity in the reproductive caste (queens and males) account for this. Possible configurations of the reproductive caste in ant colonies are, monogyny (one queen), polygyny (multiple queens), monandry (sperm supplied by one male), polyandry (sperm supplied by multiple males), and worker reproduction. [10] Colonies may be founded by haplometrosis (by one queen) or by pleometrosis (by multiple queens). [10] Each of these examples impact the overall genetic relatedness of all members of the colony.

In most ant species, colony foundation is haplometric. The queen lands after the nuptial flight, chews off her wings so they will not impede her burrowing, and excavates a main chamber. [6] After some time, she must leave the chamber and forage for food. [6]

It has been found that the configuration of the reproductive caste in A. striatus is dependent upon densities of colonizing queens. [6] Mature colonies are very competitive, so in conditions where there are many mature A. striatus colonies, or many reproductive females, queens have been observed to start a new colony together, without respect to how they are related to one another. [6] In these conditions, brood rearing can occur rapidly, all co-queens dig and share a main chamber, and tend to the same fungal garden. [6] The queens do not need to leave to forage either, resulting in minimal chances of being preyed upon. [6] More workers are produced and fungal gardens are larger. [12] But it has been observed in other Acromyrmex species, that eventually all queens except for one are executed. [6]

Seed dispersal

Many species of ants are very important to plants as a method of seed dispersal. A. striatus is no exception. It has been seen that the leaf-cutting ants forage the fruit and seeds of many different species. [4] In addition, as they cut away the more fleshy parts of the fruit, fungi cannot infect the seeds, increasing the likelihood of viable germination. [4] The ants collect the fruit and seeds and bring them back to their nest, possibly losing some seeds in transit. Usable matter is fed to the fungus, while the inedible parts are discarded immediately outside the colony. Therefore, abandoned ant nests are an important site for the next plant generation. [4] A. striatus has been recorded exhibiting this behavior in relation to many plants, including Schinus fasciculates, native to Argentina. [4] A. striatus ‘accidentally’ transports seeds of plants that have no attractive structures on their seeds designed to encourage ant transport. [13]

Distance of dispersal is entirely dependent upon the distance the ant travels, so it has been seen that seeds are carried only short distances, [4] at least when this method is compared to that of vertebrate or wind dispersal. While studies show that the soil in which leaf-cutter ants build their nests are favorable to plant growth, there is some debate among researchers whether collection by the leaf-cutter ants increases the actual rate at which germination occurs. [4] However, seedlings are negatively affected by shade, and the soil under the parent tree. [13] A. striatus removes the seed and deposits it at the nest, where conditions are sunny with favorable soil. [13] Another benefit to being shipped by ants is escaping more natural predators., [4] [13] Ripe fruit containing seeds fall underneath the tree, and vertebrates will often search in these areas. If the ants get there first, seeds will escape organisms that would actually eat the seed. [13]

See also

Related Research Articles

<span class="mw-page-title-main">Ant</span> Family of insects

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.

<i>Atta</i> (ant) Genus of ants

Atta is a genus of New World ants of the subfamily Myrmicinae. It contains at least 17 known species.

<span class="mw-page-title-main">Leafcutter ant</span> Any of 47 species of leaf-chewing ants

Leafcutter ants, a non-generic name, are any of 47 species of leaf-chewing ants belonging to the two genera Atta and Acromyrmex. These species of tropical, fungus-growing ants are all endemic to South and Central America, Mexico, and parts of the southern United States. Leafcutter ants can carry twenty times their body weight and cut and process fresh vegetation to serve as the nutritional substrate for their fungal cultivates.

<span class="mw-page-title-main">Fungus-growing ants</span> Tribe of ants

Fungus-growing ants comprise all the known fungus-growing ant species participating in ant–fungus mutualism. They are known for cutting grasses and leaves, carrying them to their colonies' nests, and using them to grow fungus on which they later feed.

<span class="mw-page-title-main">Texas leafcutter ant</span> Species of ant

The Texas leafcutter ant is a species of fungus-farming ant in the subfamily Myrmicinae. It is found in Texas, Louisiana, and north-eastern Mexico. Other common names include town ant, parasol ant, fungus ant, cut ant, and night ant. It harvests leaves from over 200 plant species, and is considered a major pest of agricultural and ornamental plants, as it can defoliate a citrus tree in less than 24 hours. Every colony has several queens and up to 2 million workers. Nests are built in well-drained, sandy or loamy soil, and may reach a depth of 6 m (20 ft), have 1000 entrance holes, and occupy 420 m2 (4,500 sq ft).

<i>Atta sexdens</i> Species of ant

Atta sexdens is a species of leafcutter ant belonging to the tribe Attini, native to America, from the southern United States (Texas) to northern Argentina. They are absent from Chile. They cut leaves to provide a substrate for the fungus farms which are their principal source of food. Their societies are among the most complex found in social insects. A. sexdens is an ecologically important species, but also an agricultural pest. Other Atta species, such as Atta texana, Atta cephalotes and others, have similar behavior and ecology.

<i>Acromyrmex</i> Genus of ants

Acromyrmex is a genus of New World ants of the subfamily Myrmicinae. This genus is found in South America and parts of Central America and the Caribbean Islands, and contains 33 known species. Commonly known as "leafcutter ants" they comprise one of the two genera of advanced attines within the tribe Attini, along with Atta.

<i>Mycocepurus smithii</i> Species of ant

Mycocepurus smithii is a species of fungus-growing ant from Latin America. This species is widely distributed geographically and can be found from Mexico in the north to Argentina in the south, as well as on some Caribbean Islands. It lives in a variety of forested habitats and associated open areas. Two studies published in 2009 demonstrated that some populations of the species consist exclusively of females which reproduce via thelytokous parthenogenesis. A detailed study found evidence of sexual reproduction in some populations in the Brazilian Amazon. Accordingly, M. smithii consists of a mosaic of sexually and asexually reproducing populations. In asexual populations all ants in a single colony are female clones of the queen. Inside the colony, the ants cultivate a garden of fungus grown with pieces of dead vegetable matter, dead insects, and insect droppings.

<i>Atta mexicana</i> Species of ant

Atta mexicana is a species of leaf-cutter ant, a New World ant of the subfamily Myrmicinae of the genus Atta. This species is from one of the two genera of advanced attines within the tribe Attini.

<i>Acromyrmex heyeri</i> Species of ant

Acromyrmex heyeri is a species of leaf-cutter ant, a New World ant of the subfamily Myrmicinae of the genus Acromyrmex.

Acromyrmex insinuator is a social parasite of the closely related Acromyrmex echinatior. This specific parasite is of particular interest as it is an opportunity to study the development of social parasitism in the Attini tribe, and provides further evidence for Emery's rule, which theorizes social parasites among insects tend to be parasites of species or genera to which they are closely related to.

<i>Acromyrmex versicolor</i> Species of ant

Acromyrmex versicolor is known as the desert leafcutter ant. A. versicolor is found during the summer months in the Colorado and Sonoran deserts when there is precipitation. They form large, distinctive nest craters that are covered with leaf fragments. Living and dead leaves are collected by workers and used to cultivate fungus gardens. Each colony can have multiple queens, if they do this is a practice called polygyny, and each queen has her own batch of “starter” fungus. This species does not sting.

<i>Pogonomyrmex occidentalis</i> Species of ant

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.

<i>Formica truncorum</i> Species of ant

Formica truncorum is a species of wood ant from the genus Formica. It is distributed across a variety of locations worldwide, including central Europe and Japan. Workers can range from 3.5 to 9.0mm and are uniquely characterized by small hairs covering their entire bodies. Like all other ants, F. truncorum is eusocial and demonstrates many cooperative behaviors that are unique to its order. Colonies are either monogynous, with one queen, or polygynous, with many queens, and these two types of colonies differ in many characteristics.

<i>Myrmecocystus mexicanus</i> Species of ant

Myrmecocystus mexicanus is a species of ant in the genus Myrmecocystus, which is one of the six genera that bear the common name "honey ant" or "honeypot ant", due to curious behavior where some of the workers will swell with liquid food until they become immobile and hang from the ceilings of nest chambers, acting as living food storage for the colony. Honey ants are found in North America, Australia, and Africa. Ant species belonging to the genus Myrmecocystus reside in North America. M. mexicanus in particular is found in the southwestern United States and parts of Mexico.

<i>Pogonomyrmex badius</i> Species of harvester ant

Pogonomyrmex badius, or the Florida harvester ant, is a species of harvester ant in the genus Pogonomyrmex. It is the only Pogonomyrmex species found on the east coast of the United States and the only one in North America known to be polymorphic. The Florida Harvester ant is commonly found in Florida scrub and other similar habitats within the Atlantic coastal plain states.

This is a glossary of terms used in the descriptions of ants.

<span class="mw-page-title-main">Pleometrosis</span> Behaviour in social insects

Pleometrosis is a behavior observed in social insects where colony formation is initiated by multiple queens primarily by the same species of insect. This type of behavior has been mainly studied in ants but also occurs in wasps, bees, and termites. This behavior is of significant interest to scientists particularly in ants and termites because nest formation often happens between queens that are unrelated, ruling out the argument of inclusive fitness as the driving force of pleometrosis. Whereas in other species such as wasps and bees co-founding queens are often related. The majority of species that engage in pleometrosis after the initial stages of colony formation will reduce their colonies number of queens down to one dominant queen and either kill or push out the supernumerary queens. However there are some cases where pleometrosis-formed colonies keep multiple queens for longer than the early stages of colony growth. Multiple queens can help to speed a colony through the early stages of colony growth by producing a larger worker ant population faster which helps to out-compete other colonies in colony-dense areas. However forming colonies with multiple queens can also cause intra-colony competition between the queens possibly lowering the likelihood of survival of a queen in a pleometrotic colony.

<i>Novomessor ensifer</i> Species of ant

Novomessor ensifer is a species of ant endemic to Mexico. A member of the genus Novomessor in the subfamily Myrmicinae, it was first described by Swiss entomologist Auguste Forel in 1899. N. ensifer was originally a part of the genus Aphaenogaster until a recent phylogenetic study concluded that Novomessor was genetically distinct and should be separated. The ant is a medium-sized species, measuring 5.5 to 10 millimetres. The ant is ferruginous-colored in some certain parts of the body, and small workers (nanitics) in incipient colonies are noticeably different in color and body structure.

<i>Leucoagaricus gongylophorus</i> Species of fungus

Leucoagaricus gongylophorus is a fungus in the family Agaricaceae which is cultivated by certain leafcutter ants. Like other species of fungi cultivated by ants, L. gongylophorus produces gongylidia, nutrient-rich hyphal swellings upon which the ants feed. Production of mushrooms occurs only once ants abandon the nest. L. gongylophorus is farmed by leaf cutter ant species belonging to the genera Atta and Acromyrmex, amongst others.

References

  1. ↑ "Species: Acromyrmex striatus". AntWeb. 2010-06-30. Retrieved 2010-08-20.
  2. 1 2 Cristiano, M., Cardoso, D., & Fernandes-Salomão, T. (2013). Cytogenetic and molecular analyses reveal a divergence between Acromyrmex striatus (Roger, 1863) and other congeneric species: Taxonomic Implications. PLoS ONE 8(3), 1-9. doi:10.1371/journal.pone.0059784
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Benedito C., L. (2005). Vegetable resources used by Acromyrmex striatus (Roger) (Hymenoptera, Formicidae) in sand dunes at Joaquina Beach, Florianópolis, Santa Catarina State, Brazil. Revista Brasileira De Zoologia, (2), 372.
  4. 1 2 3 4 5 6 7 8 9 10 Varela, R., & Teresa C., P. (2003). Dispersal of Schinus fasciculatus seeds by the leaf-cutting ant Acromyrmex striatus in a shrubland of the dry chaco, Argentina. Journal of Tropical Ecology, (1). 91
  5. 1 2 3 4 5 Ana, A., & Estela, Q. (2007). Qualitative and quantitative evaluation of the supply and harvest of herbaceous biomass by Acromyrmex striatus Roger (Hymenoptera: Formicidae) in La Pampa Province, Argentina. Gayana , (2), 203.
  6. 1 2 3 4 5 6 7 8 9 Castellani, T., Scherer, K., Locatelli, L., & Lopes, B. (1995). The occurrence of Junonia evarete (Lepidoptera: Nymphalidae) and Acromyrmex striatus (Hymenoptera: Formicidae) on Paepalanthus polyanthus (Eriocaulaceae). Journal of the New York Entomological Society, (3). 329.
  7. 1 2 Diehl, E., Cavalli-Molina, S., & de Araujo, A. (n.d). Isoenzyme variation in the leaf-cutting ants Acromyrmex heyeri and Acromyrmex striatus (Hymenoptera, formicidae). Genetics And Molecular Biology, 25(2), 173-178.
  8. ↑ Brener, A., Folgarait, P., & Protomastro, J. (n.d). Association between the Shrun Capparis retusa (Capparidaceae) and the Ants Camponotus blandus and Acromyrmex striatus (Hymenoptera, Formicidae). Revista de Biología Tropical, 40(3), 341-344.
  9. 1 2 3 4 5 Tizon, F., Pelaez, D., & Elia, O. (n.d). Effects of firebreaks on ant density (Hymenoptera, Formicidae) in a semiarid region, Argentina. Iheringia Serie Zoologia, 100(3), 216-221.
  10. 1 2 3 4 5 E., D., A. M. de, A., & S., C. (2001). Genetic variability and social structure of colonies in Acromyrmex heyeri and A. striatus (Hymenoptera: Formicidae). Brazilian Journal of Biology, (4), 667.
  11. 1 2 3 Diehlfleig, E. (1993). Sex-ratio and nuptial flight pattern of the leaf-cutting ants Acromyrmex heyeri and A. striatus (Hymenoptera, Formicidae). Insectes Sociaux, 40(1), 111-113.
  12. 1 2 DiehlFleig, E., & deAraujo, A. (1996). Haplometrosis and pleometrosis in the ant Acromyrmex striatus (Hymenoptera: Formicidae). Insectes Sociaux, 43(1), 47-51.
  13. 1 2 3 4 5 Milesi, F., & De Casenave, J. (n.d). Unexpected relationships and valuable mistakes: non-myrmecochorous Prosopis dispersed by messy leafcutting ants in harvesting their seeds. Austral Ecology, 29(5), 558-567.
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