Attini

Smith, 1858

fungus-growing ants, higher myrmicine ants

Tribe Guides

6

is a tribe of New World ants renowned for cultivating symbiotic fungi in specialized nest chambers called fungus gardens. This mutualism, dating back approximately 30 million years, represents one of the most complex examples of agriculture outside humans. The ants provision their fungal cultivars with organic substrates including plant material, insect carcasses, and , while receiving nutrition from specialized fungal structures. The tribe encompasses diverse foraging strategies, from generalized debris collection to the conspicuous leaf-cutting of Atta and Acromyrmex . Attini ants maintain intricate associations with additional microbes, including actinobacteria that produce protecting the fungal gardens from .

Pheidole crassicornis by (c) Luke Padon, some rights reserved (CC BY), uploaded by Luke Padon. Used under a CC-BY license.Cyphomyrmex by (c) Toby, some rights reserved (CC BY), uploaded by Toby. Used under a CC-BY license.Cyphomyrmex by no rights reserved, uploaded by Philipp Hoenle. Used under a CC0 license.

Pronunciation

How to pronounce Attini: /əˈtiːnaɪ/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

ants can be distinguished from other Myrmicinae by their association with fungus gardens, though this requires nest excavation. Leaf-cutting Atta and Acromyrmex are recognizable by carrying leaf fragments in processions. vary considerably in size: derived Atta workers exhibit pronounced with major workers reaching large sizes, while basal genera such as Cyphomyrmex and Mycetarotes are generally smaller. The tribe is restricted to the New World, separating it from superficially similar fungus-growing of the Old World.

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Habitat

Nests are constructed in diverse substrates including soil, rotting wood, and leaf litter. Fungus gardens are maintained in specialized chambers within these nests, requiring controlled humidity and temperature. Leaf-cutting often occupy tropical and subtropical forests, while other inhabit savannas, grasslands, and disturbed .

Distribution

New World only, ranging from the southern United States through Central and South America. The tribe is absent from the Old World, where ecological analogs (fungus-growing in Macrotermitinae) have evolved independently.

Diet

ants feed partially on cultivated fungi; larvae depend almost entirely on fungal tissue. The fungal cultivars, primarily Leucocoprineae ( Agaricaceae), degrade complex plant polymers including cellulose, hemicellulose, and pectin, making this nutrition accessible to the ants.

Host Associations

  • Leucoagaricus gongylophorus - mutualistprimary cultivated fungus, produces specialized gongylidia for consumption
  • Leucocoprinus gongylophorus - mutualistalternative name for primary fungal cultivar
  • Escovopsis weberi - specialized fungal of attine gardens
  • Streptomyces - mutualistactinobacteria producing that suppress Escovopsis
  • Pseudonocardia - mutualistactinobacteria harbored in specialized cuticular crypts and garden substrate
  • Trichosporon chiarelii - commensalyeast associated with fungus gardens

Life Cycle

Complete with , larva, pupa, and stages. Larvae are fed cultivated fungi and bacterial secretions. Colony foundation occurs when a mated carries a fungal to establish a new nest.

Behavior

Foraging strategies range from collection of insect carcasses and (basal ) to cutting and transporting fresh plant material (derived leafcutter ants). maintain gardens through weeding, , and application of secretions from metapleural glands. Males of multiple produce tyramides, transferred to females during mating that may influence reproductive development.

Ecological Role

Major decomposers in Neotropical , processing substantial quantities of plant . The mutualism facilitates nutrient cycling and soil modification. Leafcutter ants can defoliate significant vegetation areas, occasionally becoming agricultural pests. Associated microbes contribute to suppression of fungal and represent potential sources of novel antimicrobial compounds.

Human Relevance

Leafcutter ants (Atta and Acromyrmex) are significant agricultural pests in tropical regions, damaging crops and plantations. The attine microbiome, particularly actinobacteria, is investigated for biotechnological applications including novel and antifungal agents. Some compounds show activity against drug- human and cancer lines.

Similar Taxa

  • Macrotermitinae (termites)also cultivate fungi in gardens, but are Old World, have different substrate processing, and represent rather than relatedness
  • Dacetinasister subtribe to within Myrmicinae; lacks fungus

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Sources and further reading