In the face of environmental challenges, one kind of ant gets better at growing food and an African wasp species may become more cooperative.
Armed with headlamps and tweezers, American evolutionary ecologist Jonathan Shik and his team spent more than 100 hours lying on the floor of a tropical forest in Panama watching leafcutter ants going about their business.
First the researchers wanted to learn about the ants' foraging paths and preferences. Then, with the tweezers, they would withdraw from the ants' mandibles small plant pieces and place them in specially marked "evidence bags."
Tiny farmers
This painstakingly slow fieldwork was needed to answer one of the mysteries about ants: how did these tiny-brained insects evolve to become highly successful farmers in an ever-changing environment?
"Ants developed agriculture just by natural selection, without the benefits of technology or culture," said Shik, who led a team from the University of Copenhagen in Denmark and the Smithsonian Tropical Research Institute in Panama. "Ants have thrived across 60 million years of global climate change. Humans have been farming for only 10,000 years and the sustainability of our systems is under threat."
There are dozens of species of leafcutter ants and all of them harvest pieces of fresh vegetation, carefully choosing from among many plant species.
Back in the nest, they turn collected plant material into a kind of compost and use it to grow their own type of domesticated fungus. This in turn becomes a food that ants eat.
The behavior is similar to humankind's farming practices. But while human agriculture struggles to cope with climate variations, leafcutter ants manage to grow their fungus food in a range of environments from Argentina to the U.S. state of Texas.
Seeking to understand this farming resilience, Shik and his team performed a combination of field research and laboratory experiments during a five-year EU project called ELEVATE. The initiative ran from February 2018 until January 2023.
Fungal focus
"This fungal crop has certain nutritional needs for components like nitrogen, phosphorus and calcium, so figuring out how the ants select the right nutrition for their fungi across hundreds of tree species in a rainforest was a key part of the research," said Shik.
In the field, scientists also collected samples of the fungus crop from underground nests of ants for analysis.
"These balls of fungus, resembling little brains, could be found in the small cave-like chambers deep inside the nests," said Shik. "We usually used a spoon to carefully remove small parts."