By Jonny Lupsha, Wondrium Staff Writer
A biologist whose work included groundbreaking studies of ants has died. Edward O. Wilson, 92, was the first person to identify fire ants in the United States. Some ants, like leafcutter ants, are the world’s earliest farmers.
Two-time, Pulitzer Prize-winning author Edward O. Wilson, best known for his unprecedented work in entomology, has died at the age of 92. A once controversial figure who suggested a link between human behavior and genes, Wilson returned to less heated subjects and coauthored a 1991 book, The Ants, which gave new insight into the world of the common insect.
Wilson also championed conservation of different species and general biodiversity.
Once we get past their annoying presence in our kitchen, ants are fascinating creatures. In his new video series Why Insects Matter: Earth’s Most Essential Species, Dr. Scott Solomon, Associate Teaching Professor at Rice University, explains how leafcutter ants have been farming for over 60 million years.
Life on the Farm
Humans may have developed agriculture 10,000 years ago, but it turns out, we’re not alone. Ants, beetles, and termites all began farming 55 to 65 million years ago. However, instead of plants, they farm fungi.
“The most familiar insect farmers are the leafcutter ants in the genera Atta, Acromyrmex, and Amoimyrmex,” Dr. Solomon said. “Leafcutter ants can’t digest leaves themselves, so they feed the leaves to the fungus and then eat the fungus. The ants effectively use the fungus as an external digestive system.”
Dr. Solomon said that the fungi are the ants’ primary food source and give them a full range of nutrients thanks to the leaves placed on them. Ant larvae only eat fungi; so. if an ant colony loses its fungus garden to disease or other causes, millions of ants may die. In these colonies, ant sizes vary. The smallest ants stay in or near the nests, tending to larvae and keeping the fungus garden free of weeds. The largest ants are known as soldiers and they defend the colony.
“If a hungry anteater—or, say, a biologist—starts poking around in the nest, the soldiers will quickly mobilize and begin to attack the intruder,” Dr. Solomon said. “I can tell you from experience that the soldiers are very effective. Leafcutter ant jaws are very sharp, and they can cut through skin just as easily as they cut through leaves.”
Lower Attine Agriculture
The first fungus-farming ants didn’t use fresh leaves to grow their fungi. Entomologists believe that the first ants to cultivate fungi lived in the Amazon rainforest and probably raised their fungus gardens using organic material like dead leaves, parts of flowers, and even other dead insects—a practice which continues today.
“Out of about 250 species of fungus-growing ants, or attines, about one-third practice a method of growing fungi known as lower attine agriculture,” Dr. Solomon said. “These so-called lower attine ants, like species in the genera Mycocepurus, Myrmicocrypta, and some species of Cyphomyrmex make relatively small nests where they grow their fungus gardens on organic materials they find nearby.
“The fungi grown by most lower attine ants belongs to Leucocoprineae, a group that includes a species familiar to many gardeners known as the yellow pot-plant mushroom.”
Puzzlingly, 17 species of Cyphomyrmex grow their fungus as a yeast, which is a single-celled fungus. Biologists have yet to discover why they do so, but some of these yeast-growing ants can live in environments in which other fungus-growing ants cannot.
Ant agriculture may predate human agriculture by almost 60 million years, but at least we beat them to the development of the combine harvester.