Difficulty: Challenger (Level 2)
Sick young ants release a smell to tell worker ants to destroy them, scientists said in December.
This helps protect the colony from infection. However, queens do not seem to commit this act of self-sacrifice.
Saving other ants
The lead author of the new study was Erika Dawson, a behavioural ecologist at the Institute of Science and Technology Austria.
Ant nests are a “perfect place for a disease outbreak to occur because there are thousands of ants crawling over each other”, Dawson said.
When adult worker ants get an illness that could spread through the colony, they leave the nest to die alone.
But young ants, known as pupae, are trapped in a cocoon. This makes it impossible for them to isolate themselves.
Scientists already knew that when these pupae are so ill that they will die, there is a chemical change that makes a certain smell. The scent tells worker ants to destroy both the pathogen – the bacteria or virus that causes disease – and the pupae (see graphic).
Dawson said the scientists wanted to learn if the pupae were actively telling other ants to kill them.
Making a sacrifice
First, the scientists extracted the smell from the sick pupae of a small black garden ant called Lasius neglectus. When they applied the smell to a healthy brood in the lab, the workers still destroyed them.
Then, the team conducted an experiment showing that the sick pupae only produce the smell when worker ants are nearby. This proved it was a deliberate signal for destruction.
“While it is a sacrifice ... it’s also in their own interest because it means that their genes are going to survive and be passed on to the next generation,” Dawson said.
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What happened when the smell from the sick pupae was applied to healthy ants?
