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Queen leafcutters are tougher than most ants

The queen is the mother of all ants, but she dies when she can no longer fulfil her task. This is the case for most ant species except for queens of the ant genus Acromyrmex; these ants have the capacity to alter their behaviour and survive. In a new study, presented in the jo...
Queen leafcutters are tougher than most ants
The queen is the mother of all ants, but she dies when she can no longer fulfil her task. This is the case for most ant species except for queens of the ant genus Acromyrmex; these ants have the capacity to alter their behaviour and survive. In a new study, presented in the journal Current Biology, researchers from Denmark and Germany show how the Acromyrmex (i.e. leafcutter) queens defend and care for their mother colony.

Nuptial flight is the most important point of the queens' life, the period in which they mate with male ants. They lose their wings and establish their own colony. Ultimately, they are imperative to the ant lifecycle because only they have the capacity to reproduce. In order to ensure their survival, they remain in their nests. Sentries to the nests are smaller and sterile female workers, as well as soldiers.

But scientists led by the University of Freiburg in Germany have made another discovery, following field studies in Panama. 'We were very surprised to find Acromyrmex queens that defended their nest during our studies in Panama,' said lead author Dr Volker Nehring, a behavioural ecologist at Freiburg.

In the past, researchers believed that queen ants died when they lost their wings before their nuptial flight and remained unfertilised, and some of them were eaten by their sisters. But what leafcutter ants consume is fungi found in their colonies: these give the insects the nutrients they need to survive.

'We suspect that they have lost the ability to digest meat and recycle their queens,' explained Dr Nehring. 'There is thus an evolutionary advantage to keeping the sterile queens alive and making them useful for the colony in another way.' They do not really have to feed, because they live from reserves and digest their own wing muscles like the fertilised queens, according to the researchers.

Once they completed the field studies, the researchers reproduced their observations in the laboratory. Here, they stopped the queen ants from reproducing by removing their wings, effectively simulating what happens in nature. The researchers observed that the wingless queens exhibited a greatly increased level of aggressiveness when exposed to scents from foreign colonies. They found that unlike their winged sisters, these queens helped take care of the mother's offspring and engaged in nest building.

'It seems as if these princesses knew that they would never be able to mate and found their own colony without wings,' said Dr Nehring. 'So the only thing left for them to do was to help their uninjured sisters and defend the nest against invaders, like the legendary Amazons.'

Researchers from the University of Copenhagen in Denmark contributed to the study.

Source: Current Biology; University of Freiburg

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  • Germany, Denmark
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