Biomineral body armour protects leaf-cutter ants
Date: 27 November 2020 Tags: MiscellaneousIssue
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
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Biomineral armour is seen in the natural world in crustaceans like lobsters as well as in other marine animals.
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Sea urchin spines contain calcium carbonate but it has not previously been found in insects.
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Researchers noticed that the larger worker ants, known as majors, have a “whitish, granular coating” over the surface of their bodies.
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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.
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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.
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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.
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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.
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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
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Acromyrmex echinatior colonies can be formed with hundreds of thousands of large and small worker ants.
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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.
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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”.