How do leafcutter ants farm a fungus, and how do ant-plants hire bodyguards?
Leafcutter ants have farmed a fungus for about 15 million years; they cut leaves not to eat them but to feed their crop.
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Leafcutter ants do not eat the leaves they carry. They are farmers. The ants cut leaves, flowers and grasses, carry them back to the nest and feed them to a fungus that they cultivate. The fungus feeds the ant larvae, and the adults feed mostly on leaf sap. Next to humans, leafcutter ants form some of the largest and most complex animal societies on Earth: a nest can grow to more than 30 metres across and hold 3.55 million ants.
This is a partnership in which neither side can survive alone. The ants feed the fungus freshly cut plant material and keep it free from pests and molds, and the fungus needs the ants. The ants fully domesticated their fungal partner about 15 million years ago, a process that took 30 million years to complete. When a young queen leaves to found a new colony she carries a piece of the old fungus garden in a pocket in her mouth, and only about 2.5 percent of young queens succeed.
Step 1: Workers cut leaves
And carry them to the nest
Step 2: The fungus grows on the leaves
The ants feed it and keep it free of pests
Step 3: Larvae eat the fungus
Adults feed on leaf sap
Step 4: Weeding and waste
Infected pieces are removed and dumped
Farms attract pests. A parasitic fungus called Escovopsis threatens the garden, so the ants weed out infected pieces and dump them. Another partner helps too: a bacterium that grows on the ants and secretes chemicals, in effect portable . The ants even adapt to the fungus: if a type of leaf is toxic to it, they stop collecting it.
Other rainforest plants and ants have their own deals. , or myrmecophytes, offer ants shelter and food in exchange for help with defense, pollination, seed dispersal and gathering nutrients. For one ant species living on Macaranga trees, that deal is for life: it cannot survive without the nesting spaces and food bodies the plant provides. From a farmer's view, leafcutters are also a pest, and some can strip an entire citrus tree in less than 24 hours.
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Recap
Leafcutters farm a fungus with leaves as compost, weed out parasites and use bacterial antibiotics, while ant-plants swap homes for protection.
💡 A trick to remember it · Leafcutters are gardeners with a compost heap: the leaves are the manure, the fungus is the crop, and the ants never eat the leaves.
Surprising fact · A leafcutter nest can hold 3.55 million ants.
Sources (2)
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