Education

Over the past two decades, field trips in search of dung beetles have taken University of Pretoria (UP) doctoral student Christian Deschodt across Southern Africa. But it was a well-trodden walk to fetch his kids from school, a mere 1,5km from his home near Hartbeespoort, that saw him stumble upon an entirely new species.

This was just one of two new species that was recently described by Deschodt, who has been involved in the discovery and description of more than 50 new dung beetle species.

News about the species, named Hathoronthophagus spinosa, spotted on his stroll was announced in Zootaxa, a scientific journal that specialises in updates about the discovery of new species. Deschodt, together with his PhD supervisor, Professor Catherine Sole of UP’s Department of Zoology and Entomology, also placed the species in a new genus, Hathoronthophagus.

“We live near Hartbeespoort Dam on a small piece of land, some 30km from UP’s Hatfield campus,” Deschodt says. “After a morning of research work, I like to stretch my legs by taking a walk to fetch my two children from primary school.”

Never did he imagine that walking along that particular gravel farm road would allow him to combine work with his parental duties. In January 2023, Deschodt set off to fetch his children. It had rained the previous day. About 500 metres into the walk, he spotted a tiny chocolate brown dung beetle less than 5mm in size amid a hoard of common pugnacious ants. No dung was to be seen, as would be expected when dung beetles are around.

Careful not to squash it, he carried the specimen to the school and back home where, after a quick look at it under the microscope, he realised it was the female of a species that he’d never seen before. He named it after ‘Hathor’, an ancient Egyptian deity associated with joy, love, women, fertility and maternal care.

“She was often portrayed as a woman wearing a headdress of cow horns,” Deschodt explains, “which reminded me of the longish horns of Hathoronthophagus spinosa.”

Deschodt has since had no luck in tracking down more specimens, despite having put out lures baited with cattle dung and extensively examining ant nests around Hartbeespoort. He believes this particular species of dung beetle may live in ant nests, and may be providing a mutually beneficial service to its fellow insects. Incidentally, other dung beetles that have antennas with eight segments, like Hathoronthophagus spinosa, have such a relationship with ants. More work will have to be done to confirm this hypothesis.

“I hope that news about this find will at least prompt other experts working in Southern Africa to explore the relatively unknown relationship between ants and dung beetles more intensively,” he says.

There are about 500 species of dung beetle in South Africa, and more than 700 in all Southern African countries, including South Africa, Botswana, Namibia, southern Mozambique and Zimbabwe. According to Deschodt, this diversity is partly due to South Africa’s hugely varied geography and range of vegetation types, from fynbos to succulents, thickets and savannas.

He says many species of dung beetles are specific about the type of dung they use. For instance, some are only found using elephant or rhinoceros dung. For his PhD, Deschodt is working on a flightless genus found in the arid parts of Namibia and western South Africa that only keeps to rock hyrax (‘dassie’) dung pellets.

It is also a fallacy that dung beetles only feed on faeces, despite what their common name might infer. Some species have been seen scavenging on dead frogs and chicken livers, or feeding on different types of mushrooms.

Testing

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New research by scientists at the University of Pretoria (UP) has shown that pulse oximeters, originally designed for humans, can be used more effectively to monitor the blood oxygen levels of rhinoceroses who are under anaesthesia and immobilised – by attaching them at an unusual site: the rhino’s ‘third eyelid’.

“The third eyelid is a crescent-shaped fold of the outer eye structure which forms a thin, semi-transparent ‘blinking’ membrane over the eye,” explains Dr Thembeka Mtetwa, an early-career comparative physiologist of UP’s Faculty of Veterinary Science.

Immobilising rhino for dehorning or relocation is becoming a routine procedure for wildlife veterinarians working on the frontline to protect these animals from poaching. However, during these procedures, the rhino’s lungs and heart may not respond well to the potent immobilising drugs.

“The drugs can negatively affect cardio-respiratory function; this can cause blood oxygen to drop to dangerously low levels,” Dr Mtetwa says.

While the risks are managed as carefully as possible during these procedures, one of the greatest challenges to date has been identifying a reliable, field-friendly means of monitoring the animal’s blood oxygen levels. Monitoring these levels is essential for making important decisions, such as whether to administer drugs to stimulate breathing or to give oxygen to the rhino.

That is why UP researchers have been working to adapt the use of existing technology and testing it in the field to find an appropriate solution.

Up until now, scientists and vets have typically been monitoring the blood oxygen levels of immobilised rhinos with blood gas analysers and pulse oximeters – which are designed for humans, not for a 1.5- to 2.5-tonne rhino – without any certainty of their reliability. Dr Mtetwa explains that these oximeters are not that different to the kind a doctor might attach to your finger to measure your blood oxygen levels. They provide a real-time reading of the oxygen levels in the blood.

“To give the pulse oximeters the best chance of working, we had to think carefully about where to place them on the rhino’s body – where the animal’s skin and membranes aren’t too thick,” Dr Mtetwa says.

The team discovered that the rhino’s ‘third eyelid’ proved to be the most reliable site to attach the pulse oximeter.

“In humans, the third eyelid is that little pink structure snuggled in the corner of your eye that is barely noticeable  – it is vestigial and has no function,” Dr Mtetwa explains. “But in rhinos, it is, of course, much larger, and it contains lots of small blood vessels. It’s also quite noticeable in dogs, cats and other animals; it functions to protect and clear the eye of foreign bodies when it closes, and to help keep the eye moist.”

The new research by Dr Mtetwa and her collaborators – UP’s Professor Leith Meyer, a wildlife vet and physiologist; experimental physiologist Prof Ned Snelling; wildlife vet Dr Peter Buss of SANParks; wildlife vet Dr Annette Roug; and ecophysiologist Dr Ashleigh Donaldson – was recently published in the journal BMC Veterinary Research. The group tested the reliability of different pulse oximeters at various attachment sites on the body of an immobilised rhino.

Prof Meyer, who has more than 20 years of experience in wildlife chemical immobilisation, came up with the novel idea to test the feasibility of placing the device on the third eyelid.

“The colour, moisture and capillary refill time of the external mucous membranes of the body are good indicators of hydration, circulation and the overall health of the animal, and are typically good sites to place a pulse oximeter probe,” he says. “However, making use of these membranes on a rhino can be challenging due to their thickness and poor accessibility in some locations of the body, like the mouth. That’s why we decided to explore the mucous membranes of the third eyelid as an alternative option. Luckily, it turned out to be a good idea!”

“The great thing about the rhino’s third eyelid is that it is relatively thin,” Prof Snelling adds. “It has lots of blood vessels close to the surface, and it’s easy for vets and vet nurses to access it.”

“Our findings highlight the importance of using appropriate monitoring techniques in large immobilised animals like rhinos, which have unique anatomical and physiological characteristics,” Dr Mtetwa says. “This new research improves our ability to provide care and ensure the well-being of rhinos in the field.”

Click on the gallery in the sidebar to see how the procedure is done.