Several species of ant have been observed producing a liquid while in a pupal stage that is consumed by ant larvae and adults, and this is likely to occur across all ant species
Life 30 November 2022
Clonal raider ants (Ooceraea biroi) and their larvae may be nourished by a liquid secreted by pupae of the species
Daniel Kronauer
A nutrient-rich liquid that could be produced by all ant species while the insects are in their pupal stage is consumed by adults and larvae.
The creation of this fluid hadn’t been reported by researchers before, according to an editorial accompanying the research.
Ants develop in several stages. Eggs first become worm-shaped larvae with no eyes or legs. Larvae then develop into pupae, which more closely resemble adult ants but have their legs and antennae folded in. Pupae eventually become adults.
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Orli Snir at the Rockefeller University in New York isolated clonal raider ant (Ooceraea biroi) pupae from their colony. She found that the pupae secreted a liquid about six days before they hatched.
Alongside her colleagues, led by Daniel Kronauer, Snir then found that if the liquid were allowed to build up around the pupae, it led to a fungal infection and pupal death.
When the researchers removed this fluid as it accumulated, the pupae grew as expected. This may mean that pupae rely on adults and larvae to remove it somehow, says Kronauer.
Next, the researchers wanted to observe this phenomenon in a real-world setting to ensure that the liquid wasn’t being secreted due to something in the laboratory interfering with pupal development.
To test this, they injected a food dye into the so-called exuvial space of the pupae while they were in the ant colony. This space is a gap that forms between the old and new exoskeleton of the pupa as it is moulting. Within 24 hours, the larvae and adult ants in the colony had taken up the dye into their digestive tracts.
This suggests that other researchers may have missed the liquid’s production because it is consumed relatively quickly.
Next, the researchers tested the effects that exposure to this liquid had on larvae. When larvae were deprived of it in a laboratory setting, their growth was stunted and they had lower rates of survival. The liquid contains hormones and other substances that may aid their development.
The researchers are studying the liquid’s potential benefits for adult ants.
According to Kronauer, it may ensure that an ant colony acts as a unit. “This secretion really creates these dependencies across different stages,” he says.
The pupae depend on the adults and larvae to remove the liquid so that they don’t get an infection, and the larvae rely on it to aid their growth, says Kronauer.
In the final stage of the experiment, the researchers isolated the pupae of four other ant species, finding that all these species’ pupae produced a similar fluid before hatching. “There are 15,000 ant species, so we can’t say for sure, but so far it seems that all ants produce this liquid,” says Kronauer.
“In short, these results are a fascinating example of how we can still discover new fundamental mechanisms if we just look,” says Chris Reid at Macquarie University in Sydney, Australia.
“The fact that the authors show this newly discovered phenomenon is actually widespread among ants will lead to many researchers changing their way of thinking around the world,” he says.
Journal reference: Nature, DOI: 10.1038/s41586-022-05480-9
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