Honey Made by Ants Could Protect Against Bacteria and Fungi

Australian honeypot ants create and store a sugary substance that may kill microbes, per a new paper that aligns with Indigenous knowledge

Australian honeypot ants with bulging abdomens filled with honey
The abdomens of Australian honeypot ants can swell to hold honey that the colony uses as a food source when stores run low.  Auscape / Universal Images Group via Getty Images

Honey made by Australian honeypot ants can protect against some types of bacteria and fungi, according to a study published Wednesday in the journal PeerJ.

The findings are in line with Australian Indigenous knowledge. Indigenous groups have used honey from these ants as a food source and to treat colds and sore throats, according to the paper.

“Western medicine is playing catch-up with what many traditional societies have known for thousands of years,” Danny Ulrich, a member of the Tjupan language group who aided the research, tells Science’s Celina Zhao. “Indigenous knowledge is really an untapped resource.”

Australian honeypot ants gather nectar from a range of floral sources, but they’re thought to prefer a sticky, sweet substance called honeydew made by mulga trees and aphids. After aphids consume the trees’ sweet sap, the ants use their antennae to stroke the bugs, which causes them to excrete the honeydew from their anuses, the study authors write.

Worker ants collect this liquid, then feed it to certain other worker ants called repletes, whose bellies swell and become semi-transparent as they fill with the substance. The ants become so stuffed with honey that they can barely move, and they hang from the roofs of their nests. If the colony’s food stores run low, the repletes regurgitate what’s in their bellies for other ants to feed on.

“They are basically the holding vessels of the nectar that is brought in,” Andrew Dong, a co-author of the study and microbiologist at the University of Sydney, tells New Scientist’s Chen Ly.

With the help of local Indigenous guides, the researchers gathered honeypot ants and their honey from Kurnalpi, a desert town site in Western Australia. In lab experiments, the honey protected against the bacterium Staphylococcus aureus, which causes a wide range of diseases in humans, but did not protect against other bacteria. It also defended against two types of fungi called Cryptococcus and Aspergillus.

Shona Blair, a microbiologist at St. Vincent’s Health Innovation Precinct Sydney who did not contribute to the study, tells Science that she was not surprised by the findings. “Pretty much every culture that has had access to honey has used it medicinally,” she tells the publication, “all the way back to the ancient Egyptians.”

“It was quite amazing that the activity of the honey was so specific against some pathogens and not others,” Kenya Fernandes, a co-author of the study and microbiologist at the University of Sydney, tells the Guardian’s Donna Lu. “The honey was really active against some of the fungi that we consider to be really tough and really hard to kill.” The bacterium, Staphylococcus aureus, is also difficult to fight—it’s notorious for being resistant to antibiotics.

Compared to bee honey, the ant honey killed a narrower range of microbial organisms, writes New Scientist. It did not fight off the common bacterial cause of food poisoning Escherichia coli, or the yeast infection-causing fungus Candida albicans.

Still, the team hopes the ants’ honey can be further studied to determine which compounds defend against pathogens. If they can find this out, scientists hope to replicate and use those components in treatments, rather than collecting the honey itself.

“Given that the honey is such a precious resource, and it’s also something that has a lot of cultural significance to Indigenous people, it’s not really the kind of thing where you’re going to be able to take the honey directly and apply it for any kind of clinical use,” Fernandes tells the Guardian.

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