Acromyrmex

Features
By Emmett Anderson

Diversity

Acromyrmex is one of two genera of leafcutter ants, the other being Atta . There are around 35 species of Acromyrmex and around 21 sub-species. Acromyrmex as well as Atta are known for cultivating fungus within their nests for sustenance. Acromyrmex mostly inhabit grasslands, disturbed areas, and tropical forests though there are outliers such as A.versicolor which can be found in dry desert areas. There are different lifestyles that have developed within the genus as well, many species of Acromyrmex act as social parasites of other species within the genus. Some species such as A.coronatus have adapted to live in cold, wet climates like that found in dense cloud forest. They can even be pests in gardens or homes cutting up bread, cabbage or fruit. Species like A.diasi have adapted to living in swamps by building bridges and corridors from grasses to walk over water. The species A.fowleri has evolved to be a workerless social parasite which lives along side host queens. Species of Acromyrmex also range in color from black to light orange and cultivate different stains of fungus.

Geographic Range

Species of Acromyrmex are primarily Neotropical and occur from southern South America to the southern United States. A.versicolor can be found as far west as California.

Habitat

Acromyrmex can be found in grasslands, tropical forests, and disturbed areas. Some species can also be found in desert areas or swamps. Species of this genus cultivate fungi gardens which they build their nests around.

Systematic and Taxonomic History

Acromyrmex are sister to the genus Atta and are both part of the "Fungus-growing" subfamily Myrmicinae . The genus was discovered in 1865 and has had the same name since its discovery.

Physical Description

Acromyrmex can be a couple of different colors mainly being different shades of either red, brown or black. Like other insects Acromyrmex have bodies divided into three regions; head, thorax, and abdomen, as well as having external mouthparts and wings (although the wings are absent in most of the ants in a colony). Acromyrmex have a three pairs of spines used to carry vegetation and a rough exoskeleton on the upper surface of the thorax. Like most other ant genera there is a high degree of biological polymorphism within colonies of Acromyrmex within different casts which are determined by age, though less than other genera such as Atta . The main difference is size, which can range from 2-23mm.

  • Sexual Dimorphism
  • female larger
  • sexes shaped differently

Development

Acromyrmex exhibit haplodiploidy which means the queen has full control over sex determination, unfertilized eggs become males while fertilized eggs become females. Acromyrmex species, like other ants start off as eggs layed by a queen which hatch into larvae. In this stage they are cared for by workers until they are able to undergo complete metamorphosis undergoing a pupal stage before developing into the adult body plan of their species. As adults are usually separated into 2-4 castes where they will specialize in a specific task to help the colony which can consist of brood care, gatering materials, protecting the nest, or taking care of the fungal gardens as well as many other jobs.

Reproduction

Queens of Acromyrmex exhibit different mating systems within different colonies of the same species. Some species are completely monogamous such as A.lundii while others have been exhibit both polygyny and polyandry such as A.ambiguss . Most males of this genus die after reproduction.

Acromyrmex breed and lay eggs year round. Some species store the sperm of multiple males long-term such as A.echinatior . Males of most species of Acromyrmex die after reproduction.

As Acromyrmex is a mostly eusocial genus, as some species are socially parasitic, the offspring of the queen are taken care of and protected by the rest of the colony until they become an adult.

  • Parental Investment
  • post-independence association with parents
  • maternal position in the dominance hierarchy affects status of young

Lifespan/Longevity

Colonies of Acromyrmex are able to last several years. Though there is not much research on the lifespan of these ants one study showed that the workers of A. rugosus rugosus had an average lifespan of around three to seven months at a time.

Behavior

Acromyrmex are a genera of mostly eusocial species, as some species are socially parasitic. The queen is the mother of the whole colony and is protected and cared for by them. Acromyrmex are known for their fungal rearing capabilities. They will bring back materials to their nest which decay and grow fungus that will feed the whole colony. There is a hierarchy in these ants that is based off of age. Age determines the roles of workers within a colony. The youngest tend to the nest and the fungus, after three to five weeks some of these ants will begin to forage outside the nest and perform other tasks. The majority of communication for Acromyrmex is done using pheromones which can be used to communicate alarms or to produce foraging trails to gather resources. Acromyrmex Have also formed a symbiotic relationship with bacteria that covers their whole body and protects them from fungal parasites that would harm their food resource.

Communication and Perception

Like many other genera of ants Acromyrmex use pheromones as their main form of communication. Whether its to set off an alarm to warn others of danger or leading the way to resources, the pheromonal communications used by these ants are integral to the communication in the colony. Smell and picking up chemical cues is also a large part of how Acromyrmex perceive the world around them. They also have compound eyes which help them see their environment.

Food Habits

Acromyrmex are fungivores, the fungus they eat varies from species to species but these ants are known for growing it and taking care of it themselves in their nests. these "Fungal Gardens" is made from fresh green leaves or other vegetal material that the ants forage for by forming distinct trails to and from the vegetation being harvested. The harvested materials are then cut up into smaller pieces and attached to the fungal garden using anal excretions. The attached pieces are then given constant care in order to ensure fungal growth of the specific fungal species only. Also in order to combat specified fungal parasites that would harm the fungal gardens Acromyrmex have developed a mutualistic relationship with a filamentous bacteria which covers their cuticle and produces antibiotics which suppress fungal parasites.

Predation

In Acromyrmex adaptations to predators begin in their eusocial lifestyle. Specific castes in the colony have different jobs, one of these jobs is the soldiers who are specifically designated to protect the colony and the queen they are the main line of defense against an attack. Other adaptations to fight predation include a hard exoskeleton and the ability to release alarm pheromones when killed. Acromyrmex also have incredibly sharp and powerful mandibles which are mainly used to cut pieces of vegetation but can also do great damage to an attacking organism.

Ecosystem Roles

While Acromyrmex act as prey of species such as N. esenbeckii . They also have other ecosystem roles such as having an affect on the diversity, productivity, and nutrient flow in their habitats due to their foraging for their fungal gardens. The foraging trails made by Acromyrmex also temporarily change the terrain of the ecosystem as they can reach up to 17m in some species. Acromyrmex can boost the nutrient levels of soil from refuse dumps where waste is deposited by the colony. Species such as A. Vesicolor can also have large nests which change the composition of the surrounding ecosystem.

Mutualist Species
Commensal/Parasitic Species

Economic Importance for Humans: Positive

There are not many positive economic effects that come from colonies of Acromyrmex . Only a few species such as A.versicolor and A.octospinosus are kept as pets. The research being done on the genus is mainly geared towards ecological impacts and the behavior/lifestyle of the genus.

  • Positive Impacts
  • pet trade
  • research and education

Economic Importance for Humans: Negative

The main negative impacts of Acromyrmex species is their effects on crops and that they will attack humans if they encounter them. Species of Acromyrmex as well those belonging to the other genus of leaf-cutting ants Atta are well known for their defoliation capacity and can be considered major pests to crops. Leaf-cutting ants often harvest the flowers and photosynthetic tissues of plants which can have a direct effect on plant fitness.

  • Negative Impacts
  • injures humans
    • bites or stings
  • crop pest

Conservation Status

The conservation status of the species belonging to Acromyrmex is common, these different species can be easily found and are abundant. No action is being taken to change the conservation status of Acromyrmex species.

Encyclopedia of Life

Contributors

Emmett Anderson (author), Colorado State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

native range

the area in which the animal is naturally found, the region in which it is endemic.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

monogamous

Having one mate at a time.

polyandrous

Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).

polygynous

having more than one female as a mate at one time

cooperative breeder

helpers provide assistance in raising young that are not their own

eusocial

the condition in which individuals in a group display each of the following three traits: cooperative care of young; some individuals in the group give up reproduction and specialize in care of young; overlap of at least two generations of life stages capable of contributing to colony labor

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

year-round breeding

breeding takes place throughout the year

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

fertilization

union of egg and spermatozoan

internal fertilization

fertilization takes place within the female's body

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

sperm-storing

mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

diurnal
  1. active during the day, 2. lasting for one day.
parasite

an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death

motile

having the capacity to move from one place to another.

sedentary

remains in the same area

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

social

associates with others of its species; forms social groups.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

visual

uses sight to communicate

tactile

uses touch to communicate

chemical

uses smells or other chemicals to communicate

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

visual

uses sight to communicate

tactile

uses touch to communicate

chemical

uses smells or other chemicals to communicate

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

keystone species

a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

mycophage

an animal that mainly eats fungus

References

Bollazzi, M., B. Grestner. 2022. Decoupled evolution of mating biology and social structure in Acromyrmex leaf-cutting ants. Behavioral Ecology and Sociobiology , 76: 7.

Bucar, F. 2022. Behavioral Specialization of Workers of the Leafcutter Ant Acromyrmex octospinosus (Hymenoptera: Formicidae) with an External Bacterial Layer. Journal of Insect Behavior , 35/5-6: 127-135.

Calheiros, A., M. Ronque, P. Olivera. 2019. Social Organization and Subcaste Specialization in the Leaf-Cutting Ant Acromyrmex subterraneus (Formicidae: Myrmicinae). Journal of Insect Behavior , 32: 267-280.

Chan, K., R. Olivreira, P. Van Den Berg. 2022. Evolution of self-organised division of labour driven by stigmergy in leaf-cutter ants. Scientific Reports , 12/1.

Currie, C., J. Boomsma. 2002. Mutualistic bacteria and a possible trade-off between alternative defence mechanisms in Acromyrmex leaf-cutting ants. Insectes Sociaux , 49/1: 15-19.

Hefetz, A., C. Errard, J. Boomsma. 2007. The origin of the chemical profiles of fungal symbionts and their significance for nestmate recognition in Acromyrmex leaf-cutting ants. Behavioral Ecology and Sociobiology , 61/11: 1637-1649.

Roces, F. 2017. Carbon dioxide sensing in an obligate insect-fungus symbiosis: CO2 preferences of leaf-cutting ants to rear their mutualistic fungus. PLOS ONE , 12/4.

Ruggiero, A. 1994. LEAF-CUTTING ANTS (ATTA AND ACROMYRMEX) INHABITING ARGENTINA - PATTERNS IN SPECIES RICHNESS AND GEOGRAPHICAL RANGE SIZES. Journal of Biogeography , 21/4: 391/399.

Steadman, K., S. Smith, C. Smith, M. Hubbard, J. Labriado, M. Daughtry, A. Woodson, K. Caviness-Thames, F. Cuffney, C. Perez-Heydrich. 2020. Environmental factors affect foraging efficiency of leaf cutter ants in Costa Rica. Bios , 91/1: 1-8. Accessed February 29, 2024 at https://www.jstor.org/stable/26991519 .

Suen, G. 2012. The Evolutionary Innovation of Nutritional Symbioses in Leaf-Cutter Ants.. Insects , 3/1: 41-61.

Verza, S., R. Mussury, R. Camargo, A. Andrade, L. Forti. 2017. Oviposition, Life Cycle, and Longevity of the Leaf-Cutting Ant Acromyrmex rugosus rugosus. Insects , 8/3: 80.

2012. Insect Pests in Tropical Forestry, 2nd Edition Preface . London, UK: CPI Group (UK) Ltd.

2019. Complementary effects of different predators of leaf-cutting ants: Implications for biological control. Biological Control , 128: 111-117.

2017. Consequences of leaf-cutting ants on plant fitness: integrating negative effects of herbivory and positive effects from soil improvement. Insectes Sociaux , 64/1: 45-54.

1966. FUNGUS-GROWING ANTS. Science , 153/3736: 587-+.

To cite this page: Anderson, E. 2025. "Acromyrmex" (On-line), Animal Diversity Web. Accessed {%B %d, %Y} at https://animaldiversity.org/accounts/Acromyrmex/

Last updated: 2025-09-30 / Generated: 2026-03-29 19:50

Privacy Consent Preference

This website uses some essential cookies to make it work. We’d like to set additional analytics cookies to analyze site usage. We won’t set these additional cookies unless you accept them.