Leaf Cutter Ants Evolved a Biomineral Armor That Protects It From Pathogens

A new study, published in the journal Nature, has shown that leaf cutter ants evolved a biomineral armor that protects them from pathogens. Although calcareous protection is known to have evolved in many animals, the study's discovery is a first of its kind.

Ants are known to be organized and hardworking little creatures that work together to forage and build complicated nests. They look after their colony and their queen by working together.

Leaf cutter ants, in particular, have taken working together up to several notches. Classified into four different groups, leaf cutter ants play different roles in their colony to maintain the fungus in their colony that they eat.

But these top tier gardeners also get an occasional scrap that leaves them vulnerable to pathogens. Thus, they have developed an armor to protect them.

Biomineral Armor

The researchers from the University of Wisconsin-Madison are not entirely sure why the ants have suited up in a biomineral armor, assuming only that it is to protect them from pathogens.

They analyzed this armor and said that the whitish granular coating on the ants is self-made, a first of its kind in the world of insects, according to ScienceAlert.

"We have been working on these leaf-cutting ants for many years, especially focusing on this fascinating association they have with bacteria that produce antibiotics that help them deal with diseases," said University of Wisconsin-Madison microbiologist Cameron Currie, the senior author of the study.

The researchers used electron microscopy, electron backscatter, and several other techniques to analyze deeper into the biomineral armor that covers the exoskeleton of the ant. Their analysis showed that the biomineral armor is made up of a thin layer of rhombohedral magnesium calcite crystals that are about three to five micrometers in size.

Rearing Leaf Cutter Ants

Biomineral armors are more common on crustaceans like lobsters. But given that ants evolved from crustaceans, it is understandable that some of them might have retained that characteristic.

The researchers reared leaf cutter ants to know when this armor would first appear. They found that baby ants do not have the coating until they mature which hardens significantly to protect the ants.

They tried putting the ants in experimental battles to test the hardness of their exoskeleton and found that those with hard armors are more protected both in the battle and from pathogens than those who do not have the coating.

Are There More Insects With Undiscovered Armors?

The team believes that more insects in the wild have developed a protective armor like the leaf cutter ants even though they do not yet know how these have evolved.

The team wrote that they were able to find this unusual discovery because ants are among the most extensively studied tropical insects, which raise the possibility that the calcite biomineralization could be more widespread in insects than previously thought.

In that case, more research will be needed to understand it better. They also noted that this discovery could help in the development of various materials that humans can use in the future. Indeed, the field of material science is an exciting field of science, Currie said.