Ants recognize infected wounds and treat them with antibiotics

The Matabele ants (Megaponera analis), which are widespread south of the Sahara, have a narrow diet: They only eat termites. Their hunting expeditions are dangerous because termite soldiers defend their conspecifics -- and use their powerful mandibles to do so. It is therefore common for the ants to be injured while hunting.

If the wounds become infected, there is a significant survival risk.

However, Matabele ants have developed a sophisticated healthcare system: they can distinguish between non-infected and infected wounds and treat the latter efficiently with antibiotics they produce themselves.

This is reported by a team led by Dr Erik Frank from Julius-Maximilians-Universität (JMU) Würzburg and Professor Laurent Keller from the University of Lausanne in the journal Nature Communications.

Treatment Drastically Reduces Mortality

"Chemical analyses in cooperation with JMU Professor Thomas Schmitt have shown that the hydrocarbon profile of the ant cuticle changes as a result of a wound infection," says Erik Frank.

It is precisely this change that the ants are able to recognise and thus diagnose the infection status of injured nestmates.

For treatment, they then apply antimicrobial compounds and proteins to the infected wounds.

They take these antibiotics from the metapleural gland, which is located on the side of their thorax.

Its secretion contains 112 components, half of which have an antimicrobial or wound-healing effect.

And the therapy is highly effective: the mortality rate of infected individuals is reduced by 90 per cent, as the research group discovered.

Analysis of Ant Antibiotics is Planned

"With the exception of humans, I know of no other living creature that can carry out such sophisticated medical wound treatments," says Erik Frank.

Laurent Keller also adds that these findings "have medical implications because the primary pathogen in ant's wounds, Pseudomonas aeruginosa, is also a leading cause of infection in humans, with several strains being resistant to antibiotics."

Are Matabele ants really unique in this respect? The Würzburg researcher now wants to explore wound care behaviours in other ant species and other social animals.

He also wants to identify and analyse the antibiotics used by Matabele ants in cooperation with chemistry research groups.

This may lead to the discovery of new antibiotics that could also be used in humans.

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Secrets of Namibia's fairy circles demystified: Plants self-organize

Scientists have puzzled over the origin of Namibia's fairy circles for nearly half a century. It boiled down to two main theories: either termites were responsible, or plants were somehow self-organizing. Now, researchers from the University of Göttingen, benefitting from two exceptionally good rainfall seasons in the Namib Desert, show that the grasses within the fairy circles died immediately after rainfall, but termite activity did not cause the bare patches. Instead, continuous soil-moisture measurements demonstrate that the grasses around the circles strongly depleted the water within the circles and thereby likely induced the death of the grasses inside the circles. The results were published in Perspectives in Plant Ecology, Evolution and Systematics.

About 80-140 kilometres from the coast in the Namib, there are millions of fairy circles -- circular gaps in the grassland, each a few meters wide, together forming a distinctive pattern across the whole landscape and visible for miles around. The researchers followed the sporadic rain events in several regions in this desert and examined the grasses, their roots and shoots, and potential root damage induced by termites. Termites, tiny insects that live in large colonies around the world, have often been blamed for the death of the grasses. The researchers took great care to investigate the circumstances of dying grasses within fairy circles right from straight after the rainfall, which triggered the new growth of the grasses. Additionally, they installed soil-moisture sensors in and around the fairy circles to record the soil-water content at 30-minute intervals starting in the dry season 2020 to the end of the rainy season 2022. This enabled the researchers to record precisely how the growth of the new emerging grasses around the circles affected the soil water within and around the circles. They investigated the differences in water infiltration between the inside and outside of circles at ten regions across the Namib.

The data show that about ten days after rainfall, the grasses were already starting to die within the circles while most of the interior area of the circles did not have grass germination at all. Twenty days after rainfall, the struggling grasses within the circles were completely dead and yellowish in colour while the surrounding grasses were vital and green. When the researchers examined the roots of the grasses from within the circles and compared them to the green grasses on the outside, they found that the roots within the circles were as long as, or even longer than, those outside. This indicated that the grasses were putting effort into the growth of roots in search of water. However, the researchers found no evidence for termites feeding on roots. It was not until fifty to sixty days after the rainfall that root damage became more visible at the dead grasses. Dr Stephan Getzin, Department of Ecosystem Modelling at the University of Göttingen, explains: "The sudden absence of grass for most areas within the circles cannot be explained by the activity of termites because there was no biomass for these insects to feed on. But more importantly, we can show that the termites are not responsible because the grasses die immediately after rainfall without any sign of creatures feeding on the root."

When the researchers analyzed the data on soil-moisture fluctuations, they found that the decline in soil water inside and outside of the circles was very slow after initial rainfall, when grasses were not yet established. However, when the surrounding grasses were well established, the decline in soil water after rainfall was very fast in all areas, even though there were almost no grasses within the circles to take the water. Getzin explains: "Under the strong heat in the Namib, the grasses are permanently transpiring and losing water. Hence, they create soil-moisture vacuums around their roots and water is drawn towards them. Our results strongly agree with those of researchers who have shown that water in soil diffuses quickly and horizontally in these sands even over distances greater than seven meters."

Getzin adds: "By forming strongly patterned landscapes of evenly spaced fairy circles, the grasses act as ecosystem engineers and benefit directly from the water resource provided by the vegetation gaps. In fact, we know related self-organized vegetation structures from various other harsh drylands in the world, and in all those cases the plants have no other chance to survive except by growing exactly in such geometrical formations." This research has implications for understanding similar ecosystems, especially with regard to climate change, because the self-organization of plants buffers against negative effects induced by increasing aridification.

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A family of termites has been traversing the world's oceans for millions of years

Termites are a type of cockroach that split from other cockroaches around 150 million years ago and evolved to live socially in colonies. Today, there are many different kinds of termites. Some form large colonies with millions of individuals, which tend to live in connected tunnels in the soil. Others, including most species known as drywood termites, form much smaller colonies of less than 5000 individuals, and live primarily in wood.

Researchers from the Evolutionary Genomics Unit at the Okinawa Institute of Science and Technology Graduate University (OIST), alongside a network of collaborators from across the world, have mapped out the natural history of drywood termites -- the second largest family of termites -- and revealed a number of oceanic voyages that accelerated the evolution of their diversity. The research, published in Molecular Biology and Evolution, shines light on where termites originated and how and when they spread across the globe. It also confirms that some species have, in recent centuries, hitched a ride with humans to reach far-flung islands.

"Drywood termites, or Kalotermitidae, are often thought of as primitive because they split from other termites quite early, around 100 million years ago, and because they appear to form smaller colonies," said Dr. Aleš Buček, OIST Postdoctoral Researcher and lead author of the study. "But very little is actually known about this family."

Dr. Buček went on to explain how, before this study, there was very little molecular data on the family and the little understanding of the relationships between the different species that was known was based on their appearance. Previous research had focused on one genus within the family that contains common pest species, often found within houses.

To gain overarching knowledge, the researchers collected hundreds of drywood termite samples from around the world over a timespan of three decades. From this collection, they selected about 120 species, some of which were represented by multiple samples collected in different locations. This represented over a quarter of Kalotermitidae diversity. Most of these samples were brought to OIST where the DNA was isolated and sequenced.

By comparing the genetic sequences from the different species, the researchers constructed an extensive family tree of the drywood termites.

They found that drywood termites have made more oceanic voyages than any other family of termites. They've crossed oceans at least 40 times in the past 50 million years, travelling as far as South America to Africa, which, over a timescale of millions of years, resulted in the diversification of new drywood termite species in the newly colonized places.

"They're very good at getting across oceans," said Dr. Buček. "Their homes are made of wood so can act as tiny ships."

The researchers found that most of the genera originated in southern America and dispersed from there. It takes a scale of millions of years for one species to split into several after a move. The research also confirmed that, more recently, dispersals have largely been mediated by humans.

Furthermore, this study has cast doubt on the common assumption that drywood termites have a primitive lifestyle. Among the oldest lineages in the family, there are termite species that do not have a primitive lifestyle. In fact, they can form large colonies across multiple pieces of wood that are connected by tunnels underground.

Read more at Science Daily