It is said that when man learned to farm, modern civilization began. We humans credit ourselves as being very intelligent creatures capable of learning to grow crops and keep cattle, but we are hardly the first species to acquire the skill.
Fungus-growing ants practice agriculture and have been doing so for the past 50 million years according to research published in the Jan. 17 issue of Science. These ants not only grow fungus gardens underground for food but also have adapted to handling parasitic “weeds” that infect their crops.
“The ants, garden fungi, and weeds have all been co-evolving since ant agriculture first got started — that’s around 50 million years of symbiosis,” said Dr. Ted Schultz, research entomologist in the Entomology Section of the Smithsonian’s National Museum of Natural History.
The story of the mutualism between leafcutter ants and their fungal crop culminates in industrial-scale farming that surpasses, in efficiency, human farming.
Leafcutter ants are industrious creatures known for expertly carving up foliage and then carrying it back in pieces to their colony, creating neat columns of marching green armies. They use the leaves to farm fungus which they eat — they are essentially mushroom farmers.
If the leafcutter ants are the vegetable (fungus) farmers of the ant world, herder ants are the ranchers.
Herder ants, such as the prolific Argentine Ant, tend to Aphids — the little greenish plant insects that drink plant nutrients and are considered pests by every farmer on earth, except for their own six-legged keepers. Ants love the sugary substance (honeydew) aphids and other plant lice (ex. scale seen at left), excrete and treat these plant insects (also known as plant lice) as their personal herd of dairy cows.
Some species of herder ants follow the little green food machines, devouring their droppings, while others milk their herds by tickling and stroking them with their antennae to stimulate honeydew production. Whereas cows produce milk which is dispensed through the cow’s udders, aphids produce honeydew which is excreted out of the aphids’ anus.
Although this process seems very pleasant for all involved, studies show that ants sometimes tear the wings off the aphids to stop them from flying away. They also use chemicals (found on their feet) to drug the aphids, slowing them down and also preventing their wings from developing.
To compensate, ants protect their livestock from predators. They attack ladybugs spiders and anything else, that tries to feast on their herds just like we humans would ward off a pack of wolves from a herd of dairy cows. And yet, much like we eat our cattle, ants will eat aphids too.
The reasons behind this behavior is thought to be in reaction to high aphid population growth but it might also be that the ants’ nutritional needs require a source of protein, which the aphids’ bodies provide in abundance.
Researchers at Ohio State University called ants “impressive mechanical systems”. Ants may be small but they are one of the mightiest creatures on earth as they can carry up to 5,000 times their weight.
When’s the last time you saw a human dairy farmer carrying his favorite cow around in order to find a better pasture?
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