Acromyrmex octospinosus (Reich, 1793)
Acromyrmex octospinosus
General description:Acromyrmex octospinosus is a leaf cutting and fungus growing ant in the tribe Attini. The highly polymorphic workers are reddish brown to nearly black, and measure up to 7.5 mm in length. They are mainly characterized by the absence of median spines, the flattened shape of the lower pronotal spines which have a blunt or rounded tip, and sparse pubescence (Gonçalves, 1961). Like its relatives in the closely related Atta, A. octospinosus workers harvest foliage from live plants. The foliage is brought back to specialized underground chambers and used to cultivate a fungus the ants depend upon for nutrition. Acromyrmex octospinosus is considered a significant agricultural pest (Cherrett & Peregrine, 1976). The species ranges from Mexico to northern South America and into the Caribbean.
Biology:Gonçalves (1961)provides a brief overview of the species, including its ecology. Acromyrmex octospinosus can live in a wide variety of habitats, including forests, open agricultural fields and backyards. Nests are shallow and tend to smaller than those of most Atta species, and can be formed in soil, under rocks, in ravines, atop tree buttress roots, in tree crevasses, and opportunistically beneath artificial substrates including sheet metal, cement and roofing slates (Urich, 1895; Weber, 1945; Wetterer et al., 1998b). The species also harvests a wide variety of vegetable matter (Wetterer et al., 1998b).
Acromyrmex octospinosus is currently in the process of expanding its range into the Caribbean. Populations have recently been introduced to Carriacou, Curaçao and Guadeloupe and appear to be spreading (Cherrett, 1968; Cherrett & Peregrine, 1976; Mikheyev, 2008; Pollard, 1982; Solomon, 2007). The Guadeloupe population is believed to have most likely originated from a single-queen introduction from Trinidad and Tobago, although northeastern South America is also a possibility (Mikheyev, 2008; Mikheyev et al., 2006). Spread of the Guadeloupe population is slow and even (0.51 ± 0.20 km/year). The inadvertent transport of the species may be limited by the large size and easy detection of A. octospinosus queens (Mikheyev, 2008). Another factor working to limit future introductions is that the species requires large excavated cavities for their fungus gardens (Mikheyev, 2008; Wetterer et al., 1998b).
Risk statement:Acromyrmex octospinosus is considered a significant agricultural pest.
Diagnostic description:Diagnosis of worker among Antkey species. Antennae 11-segmented. Antennal club indistinct. Antennal scrobe lacking. Eyes medium to large (greater than 6 facets), but distinctly less than half head length. Antennal insertion not surrounded by a raised sharp-edged ridge. Frontal lobes do not obscure face outline between mandible and eye. Posterolateral corners of head spinose. Mandibles triangular. Dorsum of promesonotum with 3 pairs of spines or teeth. Propodeum armed with spines or teeth. Waist 2-segmented. Petiole with a distinct and upright node. Postpetiole attached to lower surface of gaster. First gastral tergite with numerous tubercles. Color reddish brown to nearly black.
Acromyrmex octospinosus is distinguished from closely related Atta species by the presence of three spines on the promesonotum (two in Atta), and the presence of tubercles on the first gastral tergite. The species is distinguished from its only congener native to the United States (A. versicolor Pergande) by its distinctly longer promesonotal spines and distinctly less sculptured head and body.
Look alikes:Atta cephalotes, Atta sexdens.
Distribution:Native range. Mexico to northern South America and into the Caribbean.
Introduced range. Includes Carriacou, Curaçao and Guadeloupe.Acromyrmex octospinosus
General description:Acromyrmex octospinosus is a leaf cutting and fungus growing ant in the tribe Attini. The highly polymorphic workers are reddish brown to nearly black, and measure up to 7.5 mm in length. They are mainly characterized by the absence of median spines, the flattened shape of the lower pronotal spines which have a blunt or rounded tip, and sparse pubescence (Gonçalves, 1961). Like its relatives in the closely related Atta, A. octospinosus workers harvest foliage from live plants. The foliage is brought back to specialized underground chambers and used to cultivate a fungus the ants depend upon for nutrition. Acromyrmex octospinosus is considered a significant agricultural pest (Cherrett & Peregrine, 1976). The species ranges from Mexico to northern South America and into the Caribbean.
Biology:Gonçalves (1961)provides a brief overview of the species, including its ecology. Acromyrmex octospinosus can live in a wide variety of habitats, including forests, open agricultural fields and backyards. Nests are shallow and tend to smaller than those of most Atta species, and can be formed in soil, under rocks, in ravines, atop tree buttress roots, in tree crevasses, and opportunistically beneath artificial substrates including sheet metal, cement and roofing slates (Urich, 1895; Weber, 1945; Wetterer et al., 1998b). The species also harvests a wide variety of vegetable matter (Wetterer et al., 1998b).
Acromyrmex octospinosus is currently in the process of expanding its range into the Caribbean. Populations have recently been introduced to Carriacou, Curaçao and Guadeloupe and appear to be spreading (Cherrett, 1968; Cherrett & Peregrine, 1976; Mikheyev, 2008; Pollard, 1982; Solomon, 2007). The Guadeloupe population is believed to have most likely originated from a single-queen introduction from Trinidad and Tobago, although northeastern South America is also a possibility (Mikheyev, 2008; Mikheyev et al., 2006). Spread of the Guadeloupe population is slow and even (0.51 ± 0.20 km/year). The inadvertent transport of the species may be limited by the large size and easy detection of A. octospinosus queens (Mikheyev, 2008). Another factor working to limit future introductions is that the species requires large excavated cavities for their fungus gardens (Mikheyev, 2008; Wetterer et al., 1998b).
Risk statement:Acromyrmex octospinosus is considered a significant agricultural pest.
Diagnostic description:Diagnosis of worker among Antkey species. Antennae 11-segmented. Antennal club indistinct. Antennal scrobe lacking. Eyes medium to large (greater than 6 facets), but distinctly less than half head length. Antennal insertion not surrounded by a raised sharp-edged ridge. Frontal lobes do not obscure face outline between mandible and eye. Posterolateral corners of head spinose. Mandibles triangular. Dorsum of promesonotum with 3 pairs of spines or teeth. Propodeum armed with spines or teeth. Waist 2-segmented. Petiole with a distinct and upright node. Postpetiole attached to lower surface of gaster. First gastral tergite with numerous tubercles. Color reddish brown to nearly black.
Acromyrmex octospinosus is distinguished from closely related Atta species by the presence of three spines on the promesonotum (two in Atta), and the presence of tubercles on the first gastral tergite. The species is distinguished from its only congener native to the United States (A. versicolor Pergande) by its distinctly longer promesonotal spines and distinctly less sculptured head and body.
Look alikes:Atta cephalotes, Atta sexdens.
Distribution:Native range. Mexico to northern South America and into the Caribbean.
Introduced range. Includes Carriacou, Curaçao and Guadeloupe.
Teks EOL
Atta (Acromyrmex) octospinosa Reich HNS
. El Hiquito, pres San Mateo (Pac.) 200 metres; nid a fleur de terre, sous un tronc; Costa Rica (P. Biolley). Exemplaires remarquablement petits, de 2,5 a 7 mm. au maximum. Neanmoins les caracteres sont typiques et le nid superficiel, si caracteristique pour l' octospinosa, ne permet aucun doute. A part les m oe urs, cette espece ressemble a s'y meprendre a l´ A. subterranea Forel HNS de Blumenau (Bresil du sud) qui, au contraire, fait des nids tres souterrains. Le caractere qui permet le mieux de distinguer ces deux especes sont les deux epines medianes que la subterranea HNS a entre les grandes epines pronotales et qui font defaut a l´octospinosa. La subterranea HNS a aussi les diverses epines plus greles et bien plus lisses (sans petits tubercules).
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Distribution:
Native range: Mexico to northern South America and into the Caribbean.
Introduced range: Caribbean: Carriacou, Curaao and Guadeloupe.
Occasionally intercepted at US Ports of entry, but no verified records of establishment.
Identification:
Diagnosis among workers of introduced and commonly intercepted species. Antennae 11-segmented. Antennal club indistinct. Antennal scrobe lacking. Eyes medium to large (greater than 5 facets), but distinctly less than half head length. Antennal insertion not surrounded by a raised sharp-edged ridge. Frontal lobes do not obscure face outline between mandible and eye. Posterolateral corners of head spinose. Mandibles triangular. Dorsum of promesonotum with 3 pairs of spines or teeth. Propodeum armed with spines or teeth. Waist 2-segmented. Petiole with a distinct and upright node. Postpetiole attached to lower surface of gaster. First gastral tergite with numerous tubercles. Color reddish brown to nearly black.
Acromyrmex octospinosus is distinguished from closely related Atta species by the presence of three spines on the promesonotum (two in Atta), and the presence of tubercles on the first gastral tergite. The species is distinguished from its only congener native to the United States (A. versicolor Pergande) by its distinctly longer promesonotal spines and distinctly less sculptured head and body.
- La Moka.
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| Sumber | http://antbase.org/ants/publications/4001/4001.pdf |
. El Hiquito, pres San Mateo (Pac.) 200 metres; nid a fleur de terre, sous un tronc; Costa Rica (P. Biolley). Exemplaires remarquablement petits, de 2,5 a 7 mm. au maximum. Neanmoins les caracteres sont typiques et le nid superficiel, si caracteristique pour l' octospinosa, ne permet aucun doute. A part les m oe urs, cette espece ressemble a s'y meprendre a l´ A. subterranea Forel de Blumenau (Bresil du sud) qui, au contraire, fait des nids tres souterrains. Le caractere qui permet le mieux de distinguer ces deux especes sont les deux epines medianes que la subterranea a entre les grandes epines pronotales et qui font defaut a l´octospinosa. La subterranea a aussi les diverses epines plus greles et bien plus lisses (sans petits tubercules).
| Lisensi | |
| Pemegang hak/Penulis | No known copyright restrictions |
| Sumber | http://atbi.biosci.ohio-state.edu/HymOnline/reference-full.html?id=4014 |
Functional adaptation:
Fungal gardens kept free of 'weeds': leaf-cutter ants
The fungus gardens grown by leaf-cutter ants are kept free of unwanted fungi and bacteria using multiple antimicrobial compounds concurrently.
"Scientists at the University of East Anglia, have shown that fungus-farming ants are using multiple antibiotics as weed killers to maintain their fungus gardens…ants use the antibiotics to inhibit the growth of unwanted fungi and bacteria in their fungus cultures which they use to feed their larvae and queen
"These antibiotics are produced by actinomycete bacteria that live on the ants in a mutual symbiosis.
"Although these ants have been studied for more than 100 years this is the first demonstration that a single ant colony uses multiple antibiotics and is reminiscent of the use of multidrug therapy to treat infections in humans.
"…Dr Hutchings' research investigates the Acromyrmex octospinosus leaf cutter ant, endemic in South and Central America and the southern US." (EurekAlert! 2010)
Learn more about this functional adaptation.
- Barke J; Seipke RF; Gruschow S; Heavens D; Drou N; Bibb MJ; Goss RJM; Yu DW; Hutchings MI. 2010. A mixed community of actinomycetes produce multiple antibiotics for the fungus farming ant Acromyrmex octospinosus. BMC Biology. 8(1): 109.
- 2010. Ants found to use multiple antibiotics as weed killers. EurekAlert! [Internet],
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| Pemegang hak/Penulis | (c) 2008-2009 The Biomimicry Institute |
| Sumber | http://www.asknature.org/strategy/e26189eb7f07b5fe28dd58d4c9904f15 |
Acromyrmex octospinosus:
 |
This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. (August 2014) |
Acromyrmex octospinosus is a species of New World ants of the subfamily Myrmicinae of the genus Acromyrmex. It is found in the wild naturally in Central America ranging from southern Mexico down to Panama; and across northern South America in Venezuela.
Overview[edit]
Profile view of ant Acromyrmex octospinosus specimen
Commonly known as "leaf-cutter ants" they are a species of ant from one of the two genera of advanced attines within the tribe Attini.
Acromyrmex can be identified from the closely related Atta genus of leafcutter ants since they have 4 pairs of spines and a rough exoskeleton on the upper surface of the thorax.
A mature Acromyrmex octospinosus colony has a relatively small colony size of approximately 50,000 ants, mostly sterile female workers. They are divided into castes, based mostly on size, that perform different functions. Acromyrmex exhibit a high degree of biological polymorphism, four castes being present in established colonies - minims (or "garden ants"), minors, mediae and majors. Majors are also known as soldiers or dinergates. Each caste has a specific function within the colony. Acromyrmex ants are less polymorphic than the other genera of leafcutter ants Atta, meaning that there is comparatively less differential in size from the smallest to largest types of Acromymex. The high degree of polymorphism in this genus is also suggestive of its high degree of advancement.
It takes around 18 months for the colony to reach maturity but the queen of Acromyrmex octospinosus colony lives for 10 to 12 years and lays around 600 eggs per day at her peak.
Like Atta, Acromyrmex subsists mostly on a particular species of fungus (genus Leucocoprinus) which it cultivates on a medium of masticated leaf tissue. This is the sole food of the queen and other colony members that remain in the nest. The media workers also gain subsistence from plant sap they ingest whilst physically cutting out sections of leaf from a variety of plants.
Head view of ant Acromyrmex octospinosus specimen
Before leaving their parent colonies, winged females take a small section of fungus into their bucchal pouches and it is with this that the subsequently wingless queens 'seed' the fungus gardens of incipient colonies, cutting and collecting the first few sections of leaf themselves.
Acromyrmex has evolved to change foodplant constantly, preventing a colony from completely stripping off leaves and thereby killing trees, thus avoiding negative biological feedback on account of their sheer numbers. However, this does not diminish the huge quantities of foliage they harvest and the amount of foliage they strip means they have become agricultural pests on the various Caribbean islands they have been introduced on, such as Guadeloupe.
Foundresses of the leaf-cutting ant Acromyrmex octospinosus forage for leaves as garden substrate (semi-claustral foundation). The fungal pellet and substrate usually are attached to rootlets, which are used as a platform for the garden. This arrangement keeps the garden suspended away from the earthen chamber of the underground nest during early colony growth, and it serves to minimize contact between the garden and contaminants. A. octospinosus foundresses produce from 3 to 7 workers in 2.7 months after founding the nest, but workers do not forage for substrate at this time. Incipient nests died or were abandoned at a monthly rate of about 50%. The ants routinely clean their legs before manipulating the garden substrate. The foundresses use their fore-legs to rub the surface of the metapleural gland, and they then use typical grooming behaviors to pass the forelegs through the mouthparts, after which the ant then licks the garden substrate. Similarly, ants apparently use their mouths to transfer fecal droplets to their legs. These grooming behaviors are prophylactic behaviors that may help the foundress maintain a hygienic garden.
Subspecies[edit]
The species Acromyrmex octospinosus contains the following subspecies
- Acromyrmex octospinosus cubanus Wheeler, 1937
- Acromyrmex octospinosus echinatior Forel, 1899
- Acromyrmex octospinosus ekchuah Wheeler, 1937
- Acromyrmex octospinosus inti Wheeler, 1937
- Acromyrmex octospinosus octospinosus Reich, 1793
- Acromyrmex octospinosus volcanus Wheeler, 1937
Synonyms[edit]
References[edit]
- Fernandez-Marin, H., J. K. Zimmermann, and W. T. Wcislo (2003) Nest-founding in Acromyrmex octospinosus (Hymenoptera, Formicidae, Attini): demography and putative prophylactic behaviors. Insectes Sociaux 50:304-308.
- Schultz, T. R., D. Bekkevold, and J. J. Boomsma (1998) Acromyrmex insinuator new species: an incipient social parasite of fungus-growing ants. Insectes Sociaux 45:457-471.
- Wetterer, J. K. (1991) Foraging ecology of the leaf-cutting ant Acromyrmex octospinosus in a Costa Rican rain forest. Psyche 98:361-371.
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| Sumber | http://en.wikipedia.org/w/index.php?title=Acromyrmex_octospinosus&oldid=621530020 |
Gonçalves (1961)provides a brief overview of the species, including its ecology. Acromyrmex octospinosus can live in a wide variety of habitats, including forests, open agricultural fields and backyards. Nests are shallow and tend to smaller than those of most Atta species, and can be formed in soil, under rocks, in ravines, atop tree buttress roots, in tree crevasses, and opportunistically beneath artificial substrates including sheet metal, cement and roofing slates (Urich, 1895; Weber, 1945; Wetterer et al., 1998b). The species also harvests a wide variety of vegetable matter (Wetterer et al., 1998b).
Acromyrmex octospinosus is currently in the process of expanding its range into the Caribbean. Populations have recently been introduced to Carriacou, Curaçao and Guadeloupe and appear to be spreading (Cherrett, 1968; Cherrett & Peregrine, 1976; Mikheyev, 2008; Pollard, 1982; Solomon, 2007). The Guadeloupe population is believed to have most likely originated from a single-queen introduction from Trinidad and Tobago, although northeastern South America is also a possibility (Mikheyev, 2008; Mikheyev et al., 2006). Spread of the Guadeloupe population is slow and even (0.51 ± 0.20 km/year). The inadvertent transport of the species may be limited by the large size and easy detection of A. octospinosus queens (Mikheyev, 2008). Another factor working to limit future introductions is that the species requires large excavated cavities for their fungus gardens (Mikheyev, 2008; Wetterer et al., 1998b).
| Lisensi | http://creativecommons.org/licenses/by-sa/3.0/ |
| Pemegang hak/Penulis | Eli Sarnat, Antkey |
| Sumber | http://antkey.org/node/33490 |
Acromyrmex octospinosus is a leaf cutting and fungus growing ant in the tribe Attini. The highly polymorphic workers are reddish brown to nearly black, and measure up to 7.5 mm in length. They are mainly characterized by the absence of median spines, the flattened shape of the lower pronotal spines which have a blunt or rounded tip, and sparse pubescence (Gonçalves, 1961). Like its relatives in the closely related Atta, A. octospinosus workers harvest foliage from live plants. The foliage is brought back to specialized underground chambers and used to cultivate a fungus the ants depend upon for nutrition. Acromyrmex octospinosus is considered a significant agricultural pest (Cherrett & Peregrine, 1976). The species ranges from Mexico to northern South America and into the Caribbean.
| Lisensi | http://creativecommons.org/licenses/by-sa/3.0/ |
| Pemegang hak/Penulis | Eli Sarnat, Antkey |
| Sumber | http://antkey.org/node/33490 |
Native range. Mexico to northern South America and into the Caribbean.
Introduced range. Includes Carriacou, Curaçao and Guadeloupe.
| Lisensi | http://creativecommons.org/licenses/by-sa/3.0/ |
| Pemegang hak/Penulis | Eli Sarnat, Antkey |
| Sumber | http://antkey.org/node/33490 |