Ants grow their own food

PUBLISHED : Tuesday, 02 March, 1999, 12:00am
UPDATED : Tuesday, 02 March, 1999, 12:00am

Did you know some kinds of ants actually grow their own food? The nickname 'gardeners of the ant world' is given to the leafcutter ants of Central and South America because they work just like farmers or gardeners - but using their powerful saw-toothed jaws instead of a harvesting machine, and making use of fresh living plants instead of soil.

And they grow fungi, not grains or vegetables. Leafcutters are the only ants to exploit living plants for their food production - other fungus-growing ants cultivate their fungus with dead organic matter such as insect corpses and withered plants.

Amazingly, about 15 per cent of all South American rainforest leaf production is removed by leafcutter ants.

Like other ants, the leafcutters have their own 'caste' system. The largest workers are the foragers, who cut the leaves and haul them back to the nest where smaller workers chop them into little bits.

Then ants belonging to another 'caste' chew the bits into pulp and add some enzyme-rich faecal fluid as fertiliser. This is the 'soil' in which a small amount of previously-grown fungus from an older chamber is planted. As the fungus grows, other ants clean and weed the garden. Finally, the 'crops' are harvested for all the family members to eat.

Leafcutter ants posses amazing speed and strength. Scientists have estimated that, in human terms, each worker ant runs the equivalent of a four-minute mile for about 30 miles (48 kilometres) while carrying a 90 kilogram load on its back.

Although leafcutters consume huge numbers of living leaves, they seldom strip a tree bare. To avoid getting too much of any one type of fungicidal chemical the ants constantly shift their leafcutting activities to new plants.

WWF HK is a local charity environmental organisation established in 1981 which aims to build a future in which people can live in harmony with nature. For information, call 2526 1011 or e- mail to