Ants – Scottie's Playtime

Biologists antagonised ants and found out they can hold grudges

January 12, 2025 Imma Perfetto

A closeup photo of a common black ant standing on the sharpened point of a stick of wood. — ***Black garden ant (Lasius niger). Credit: Aditya Vistarakula/Getty Images***

Previous research has shown that ant colonies are more likely to behave aggressively towards neighbouring colonies, but less likely to do so against unfamiliar ones.

It’s known as the “nasty neighbour effect” and, until now, researchers weren’t sure why it exists.

A new Current Biology study has discovered that ants remember the smell of their enemies.

“We often have the idea that insects function like pre-programmed robots,” says Volker Nehring from the University of Freiburg, Germany.

“Our study provides new evidence that, on the contrary, ants also learn from their experiences and can hold a grudge.”

The researchers pitted colonies of the black garden ant, Lasius niger, against each other. In the first phase of the experiment, they were exposed either exposed to nestmates or to ants from a different colony.

Each meeting lasted for one minute and was repeated once per day for 5 consecutive days. Ants’ aggression when encountering non-nestmates increased significantly during this training phase.

On day 6, the team found that ants acted most aggressively when encountering the non-nestmate colony they had previously fought but were less aggressive towards ants from a non-nestmate colony they hadn’t yet encountered. Unsurprisingly, they weren’t aggressive towards their own nestmates.

In the second phase of the experiment, encounters were repeated with either aggressive or passive ants from a different colony. They found the ants that had previously only encountered passive competitors behaved significantly less aggressively.

Because ants use odours to distinguish between members of their own nest and those from other nests, the study suggests that ants learned to associate aggression with the non-nestmate colony’s specific scent.

Nehring and his team now plan to investigate whether and to what extent ants adapt their olfactory receptors to their experiences.

Originally published by Cosmos as Biologists antagonised ants and found out they can hold grudges

Catastrophe might have created the first ant farms

October 4, 2024 Ariel Marcy

When an asteroid slammed into Earth 66 million years ago, it caused a mass extinction. Now researchers have evidence that this catastrophe ushered in the invention of agriculture by ants.

“Extinction events can be huge disasters for most organisms, but it can actually be positive for others,” says Ted Schultz, curator of ants at the Smithsonian National Museum of Natural History and senior author of the paper. “At the end of the Cretaceous, dinosaurs did not do very well, but fungi experienced a heyday.”

What’s the link between fungi and ants?

Close up of a worker ant on top of a fungus farm — A worker ant of a fungus-farming species in Brazil. Credit: Don Parsons

The researchers propose this anti-culture heyday began with a cataclysmic collision that filled the atmosphere with debris and blocked out the sun, halting photosynthesis for years. As plants died en masse, they littered the ground with organic matter.

Fungi proliferated and ants ate the fungi for food. Some ants continued to eat fungi after Earth’s ecosystems rebounded and today more than 250 ant species have adapted and actively create conditions for fungus to thrive.

“Ants have been practicing agriculture and fungus farming for much longer than humans have existed,” says Schultz.

To pinpoint when this symbiotic interaction began, Schultz and colleagues amassed the largest genetic dataset of fungus-farming ants.

They also analysed the genetics of hundreds of fungi species, including those that are farmed by ants and their wild relatives.

Next, the team assembled evolutionary trees for both ants and fungi which revealed that farming ants and their fungus crops have been intertwined for 66 million years.

The data also revealed that “higher” forms of agriculture, where ants and fungi are completely reliant on one another, evolved around 27 million years ago. This coincided with a rapid global cooling event that fractured tropical environments. These changes led to ants cultivating a fungus outside its natural habitat.

“The ants domesticated these fungi in the same way that humans domesticated crops,” says Schultz. “What’s extraordinary is now we can date when the higher ants originally cultivated the higher fungi.”

Like humans, ant agriculturists have dealt with familiar challenges including the problems with monoculture and the trade-offs of selecting for higher food yields.

“We could probably learn something from the agricultural success of these ants over the past 66 million years,” says Schultz.