Current Affairs

Issue

Scientists have discovered in that a well-known leaf-cutting ant grows its own body armour using biominerals, a protective power previously unknown in the insect world.

 

Background

Researchers made the discovery while investigating the relationship between the fungus-growing ant species Acromyrmex echinatior and antibiotic-producing bacteria.

 

Details

• Biomineral armour is seen in the natural world in crustaceans like lobsters as well as in other marine animals.

• Sea urchin spines contain calcium carbonate but it has not previously been found in insects.

• Researchers noticed that the larger worker ants, known as majors, have a “whitish, granular coating” over the surface of their bodies.

• Later they identified it was a biomineral layer that develops as the ants mature, increasing the hardness of their exoskeleton and covering nearly the entire body.

• While researchers do not know for certain why the ants have this unusual armour, they suspect it has a lot to do with the soldier ants of another species of fungus-growing ants, Atta cephalotes. 

• The two species will often engage in territorial “ant wars”. When the Acro majors are without their armour the Atta soldiers quickly cut them into pieces.

• Studies also suggest it also helps protect them against infection from the disease-causing fungus Metarhizium anisopliae, which might otherwise spread quickly through their dense colonies.

• The Acromyrmex echinatior armour is made from a high-magnesium calcite. This is a rare form of biomineralisation where the increased hardness from the magnesium is thought to help them grind up limestone.

 

Ant colonies

• Acromyrmex echinatior colonies can be formed with hundreds of thousands of large and small worker ants.

• The large ones do the cutting and carrying of leaves, as well as engaging in wars and battles with other ants. The small ones do the gardening.

• Atta colonies are bigger, composed of perhaps millions of ants, with up to seven different sizes of workers, including soldiers for “defence and ant wars”.