Leafcutter Ant (Atta cephalotes) Fact Sheet: Diet & Feeding

Specialized herbivores and fungus farmers

• Use fresh plant material, mainly leaf fragments, to cultivate a specialized fungus (Leucoagaricus gongylophorus) as a main food source (e.g., Belt 1874; Stahel 1943; Weber 1966; Cherrett 1968; Hölldobler and Wilson 1990; De Fine Licht and Boomsma 2010; Shik et al. 2018)

• Also harvest flowers and fruit parts (De Fine Licht and Boomsma 2010; Hölldobler and Wilson 2011; Meyer et al. 2013; Crumière et al. 2022)
  • Appears to aid nutritional resiliency of cultivated fungus (Crumière et al. 2021)
• Plant matter harvested mainly from tree canopy (e.g., Cherrett 1968; Hölldobler and Wilson 2011)

• Fungus’ tiny bulbous tip structures (gongylidia) harvested by workers and liquids fed to larvae and pupae (Müller 1874; Brent 1886; Möller 1893 cited by Hölldobler and Wilson 1990; Wheeler 1907; Stahel 1943; Quinlan and Cherrett 1979; Hölldobler and Wilson 1990; Hölldobler and Wilson 2009; Hölldobler and Wilson 2011; De Fine Licht et al. 2014; Shik et al. 2018)
  • Staphylae (gongylidia that grow in clusters/bundles) rich in lipids and carbohydrates; hyphae (threadlike growths of fungus) rich in proteins (Quinlan and Cherrett 1979; Hölldobler and Wilson 2011)
  • Atta larvae entirely dependent on fungus for food (Quinlan and Cherrett 1979; Shik et al. 2018))
  • For early discussion, see references in Bailey (1920) and papers by J.E. Tanner, cited by Wheeler (1907)
• Plant liquids (saps, nectars) ingested by adult foragers (Weber 1972a; Littledyke and Cherrett 1976; Quinlan and Cherrett 1979; Hölldobler and Wilson 2011), though their dietary/nutritional role, as a supplement to fungal liquids, remains unclear (Shik et al. 2018)
  • Foragers have more nutritional flexibility than previously known (thought to be a “fungus-only” diet) (Littledyke and Cherrett 1976; Shik et al. 2018)
    • Shik and colleagues propose gut microbes may facilitate sugar digestion (Shik et al. 2018, citing Sapountzi et al. 2015)
  • Most energy requirements of foragers, gardening ants, and developing larvae still met through ingesting liquids from cultivated fungal gongylidia (Quinlan and Cherrett 1979; Rytter and Shik 2016; Shik et al. 2018)

Eggs as food

• In early colony founding, queen lays nonviable (trophic) eggs, which workers feed to larvae (Hölldobler and Wilson 2009; Hölldobler and Wilson 2011)
• Queen also eats eggs during initial period of colony founding (Hölldobler and Wilson 2009; Hölldobler and Wilson 2011)
  • Does not feed on small fungus used to start gardens

Other diet items

• Seek out patchy nutrients, such as sodium, when available (Chavarria Pizarro et al. 2012)
  • Unknown if consume themselves or use to cultivate fungus or brood (Chavarria Pizarro et al. 2012)
• Opportunistically exploit insect or vertebrate carcasses (Lachaud et al. 2019)
  • One report of opportunistic predation scar tissue and wound sites of a large mammal (Lachaud et al. 2019)
• A species in the sister genus Acromyrmex observed foraging for mushrooms (Lechner and Josens 2012)

Water requirements

• Observed drinking water when offered foods with low water content (Stahel 1943; Weber 1972b)

Finding plant material

• Explore near nest before heading to food sites each day (Lewis et al. 1974)
• Leave nest with digestive organs full of liquids to provide energy during foraging activities [in a study of Atta and Acromyrmex ants] (Rytter and Shik 2016)
• Follow pheromone trails between nest and food source — usually leaf harvesting sites in tree canopy (e.g., Wilson 1974; Jaffe and Howse 1979; Bradshaw et al. 1986)
  • See “Olfactory communication”
• Sticky pads and curved claws on leg tips help leaf-cutter ants grip vertical surfaces to reach tree canopy (Stark et al. 2019)
• Colony members exchange information about food source location (Farji-Brener et al. 2010)
  • See “Ant trails”
• Forage up to 120 m (390 ft) from the nest (Hubbell et al. 1980)

Plant selection

• Ants evaluate leaf quality based on a combination of plant chemistry, nutrient content, and palatability (i.e., leaf tenderness, vein thickness) (e.g., Cherrett and Seaforth 1970; Howard 1988; Farji-Brener 2001; Hölldobler and Wilson 2009)

• A. cephalotes tend to favor more woody types of plants (e.g., Blanton and Ewel 1985; de Paiva Farias et al. 2018)
  • Some appear to prefer younger growth and leaves without waxy coatings (Littledyke and Cherrett 1978)

• Avoid plant species that harm fungus garden growth (Hölldobler and Wilson 2009; Hölldobler and Wilson 2011) and with high endophyte loads (Estrada et al. 2013)
  • Crumière et al. (2022) showed while tannins harm fungal growth, they did not limit foraging choices that provide optimal nutrient profiles for cultivating fungus [Atta colombica]
• Workers recruited to different food sources based on body size (e.g., larger workers to more dense food types) (Rudolph and Loudon 1986)
  • Larger workers recruited to thicker leaf types (Rudolph and Loudon 1986)
• Newly founded colonies cut more delicate plants (e.g., grasses, ferns), whereas larger, established colonies harvest more thick leaf material (Wetterer 1994)
  • But leaf toughness slows cut speed for workers of all sizes (Nichols-Orians and Schultz 1989)

Cutting

• Sharp mandibles for cutting leaves (Brent 1886; Tautz et al. 1995; Schofield et al. 2011)
• Make circular (or semicircular) cuts into leaf (Wetterer 1991)
  • 20 to 50 bites to cut one leaf, depending on fragment size (Tautz et al. 1995)
• Anchor hind legs on leaf edge and pivot around body axis (Hölldobler and Wilson 2009; Hölldobler and Wilson 2011)
  • Push mandibles (cutting jaws) through leaf tissue
  • For thick leaf veins, move entire body back and forth for added leverage (Tautz et al. 1995)
• While cutting, one mandible cuts while the other remains fixed in place (Tautz et al. 1995; Hölldobler and Wilson 2009; Hölldobler and Wilson 2011)
  • Also see “Vibratory organ”
• Mandibles wear down over time (Schofield et al. 2011)
  • Foragers with the most worn mandibles only carry leaves
    • Reduces time and energy costs
  • Individual ants may switch from cutting to carrying or debris removal roles, extending their work span over a life span
    • See “Labor (caste) system”
    • See “Nest maintenance activities”

Carrying food back to nest

• Carry leaf fragment vertically overhead, back to nest (e.g., Belt 1874; Rudolph and Loudon 1986)
• Foraging ants can carry a load up to 6 to 9 times their body weight (Wetterer 1991; Burd 2000; Segre and Taylor 2019)
  • Loads up to 6 times more typical (Rudolph and Loudon 1986; Wetterer 1991)
• Forager size corresponds to leaf fragment size for efficient foraging [Atta sexdens] (Wilson 1980b)
  • Thought to match load size with carrying ability to maintain fast walking speed (Rudolph and Loudon 1986; Roces and Hölldobler 1994; Farji-Brener et al. 2011; Hölldobler and Wilson 2011)
    • Larger ants walk faster
    • Individual carrying performance reduced to maximize colony performance

Leaf processing

• Leaf fragments processed and stored in subterranean nest chambers (Belt 1874; Brent 1886; Mueller et al. 2005)
  • Inside nest, leaves cut into small fragments (about 1 to 2 mm across), then incorporated into sponge-like fungal structure (Belt 1874; Stahel 1943; Hölldobler and Wilson 1990; Hölldobler and Wilson 2011; Garrett et al. 2016)
  • See Nests
• Fungus tuft plucked from established fungus garden and transferred to new plant material (Hölldobler and Wilson 2011; Garrett et al. 2016)
  • Ants press fungal threads into cut leaf edges with front legs
  • Fungus grows quickly, covering most of leaf surface within 24 hr
• Leaf processing takes up to 12 hours (Stahel 1943)

Fungus propagation

• Minor and media workers tend fungus gardens (Hölldobler and Wilson 2011)
  • Also see “Labor (caste) system”
• Propagate new plant matter on upper garden mass surface, where new fungus grows, and discard decomposing matter in lower area of garden (Stahel 1943; Weber 1969; Shik et al. 2018)
  • Food produced continuously
  • Nutrients appear to cycle through fungus garden in less than a month (Shik et al. 2018)
• If leaf-limited, ants prune fungal gardens more intensively to stimulate food growth (M. Bass 1997)
• If dry conditions, move portions of fungal garden mass to chambers with higher humidity (Hölldobler and Wilson 2009)

Fertilizer

• Workers use their feces to fertilize fungal gardens (Martin 1970; Weber 1972b; Quinlan and Cherrett 1979; Hölldobler and Wilson 2009; Hölldobler and Wilson 2011)
  • Fungal enzymes produced in bulbous tip structures (gongylidia) ingested and cycled back to fungus (in Acromyrmex spp.: Schiøtt et al. 2010; De Fine Licht et al. 2013; Kooij et al. 2014; Kooij et al. 2016)
    • Enzymes still active even after ingestion and excretion by ants
• Fecal droplets from a different colony hinder fungus growth (Hölldobler and Wilson 2009; Hölldobler and Wilson 2011)
  • Allows fungus to control the genetic composition of new gardens in the nest
    • Non-related fungi suppressed or eliminated
  • Holds ants in an obligate-dependent relationship with their fungal host

Protecting food gardens from pathogens

• Ants use chemical secretions, antimicrobial compounds, garden bacterial biofilms, gardening behaviors, and strict waste disposal practices to maintain monoculture (e.g., Hölldobler and Wilson 1990; Currie et al. 1999; Currie and Stuart 2001; Currie et al. 2003; Mueller et al. 2005; Schoenian et al. 2011; Mueller 2012; Della Lucia et al. 2014)
• Clean new plant material before adding to fungal garden and groom existing gardens (Weber 1972b; Hölldobler and Wilson 2011; Swanson et al. 2019)
  • Contain waste inside mouth and dispose of in refuse chambers (Little et al. 2003)
• Some Atta species remove competing fungal spores (pathogens) and excise affected leaf matter (Hölldobler and Wilson 1990; Currie and Stuart 2001, and as noted)
  • Spores sterilized inside mouth pocket, possibly by a bacterium (Stahel 1943)
  • Some, such as genus Escovopsis, considered parasitic or “crop diseases” (e.g., Currie et al. 1999; Mueller et al. 2005; Hölldobler and Wilson 2009)
    • Only known to live in leafcutter ant fungal gardens
    • Overgrowth may force ants to find new nest site
• Growth of competing microorganisms (bacteria, yeasts, non-food fungi) not eliminated but suppressed to very low levels (Currie 2001; Hölldobler and Wilson 2009; Hölldobler and Wilson 2011; Reis et al. 2015)
  • Fungal gardens include fungi other than L. gongylophorus (food source) (Fisher et al. 1996; Mueller 2012; Reis et al. 2015)
• Colony also protects its unique symbiotic fungal strain against competing strains of other leafcutter ant colonies (Hölldobler and Wilson 2009; Hölldobler and Wilson 2011)

Leafcutter ants harvest leaf fragments, flowers, and fruit parts from hundreds of different plants.

Farming ants process huge amounts of plant matter underground to cultivate Leucoagaricus gongylophorus. This specialized fungus produces liquids that the ants depend on, almost entirely, as their food source.

Leafcutter ants keep their long foraging trails keep clear of vegetation. Along these routes, ants share information about plant quality though pheromone marking and head-to-head encounters.

Image credits: © San Diego Zoo Wildlife Alliance. All rights reserved.

Leafcutter ants have sharp mandibles for cutting leaves.

One mandible cuts while the other remains fixed in place. An organ on the ant's abdomen generates vibrations that boost cutting efficiency, working similarly to an electric knife or jigsaw.

Image credit: © Filo gèn' via Wikimedia Commons. Some rights reserved (CC BY-SA 4.0).

Minor and media workers tend an underground fungus garden.

A colony's specialized fungus produces liquids that workers ingest and feed to many larvae. Workers prune the fungus and add their feces as fertilizer to stimulate continuous growth.

Workers use many strategies — including cleaning behaviors, antimicrobial compounds, bacterial biofilms, and strict waste disposal practices — to maintain a monoculture.

Image credits: © San Diego Zoo Wildlife Alliance. All rights reserved.

Illustration of fungal staphylae, a cluster of gongylidia.

Ants harvest these tiny bulbous-tip structures for the liquid food inside.

Image credits: © Meike Piepenbring via Wikimedia Commons. Some rights reserved (CC BY-SA 3.0).