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14 August 2024 | Story Martinette Brits | Photo Supplied
Dr Luther van der Mescht
Dr Luther van der Mescht, Senior Lecturer in the Department of Zoology and Entomology.

Ticks that feed on South Africa’s cattle are developing resistance to the only effective pesticides, making them increasingly difficult to control. If this issue is not addressed, the spread of these parasites and their resistance to pesticides could significantly impact farmers' incomes and food security.

According to a study by Dr Luther van der Mescht, Senior Lecturer in the Department of Zoology and Entomology, many tick populations in South Africa are resistant to at least two of the three main types of acaricides (chemical classes) used in the country.

Dr Van der Mescht notes that with around 12 million cattle in South Africa, these ticks not only lower meat and milk production but also carry pathogens that can cause potentially fatal diseases. He estimates that the economic losses from tick-borne diseases and the use of acaricides could reach up to R670 million annually in the cattle industry alone.

He adds that South Africa's agricultural sector is unique due to its dual farming system, which includes both subsistence and commercial farmers, amplifying the impact of ticks. “The country is also home to a wide variety of tick species that transmit numerous pathogens across a diverse range of habitats and climates in which cattle are farmed. Consequently, the effects of ticks and tick-borne diseases in South Africa may be more severe compared to those in developed countries.”

Dr Van der Mescht highlights that ticks are developing resistance primarily due to poor farm management practices, such as underdosing, overdosing, and excessive use of acaricides. “Additionally, insufficient government support in educating farmers and managing resistance exacerbates the problem.”

Managing acaricide resistance

Dr Van der Mescht explains that while ticks will inevitably develop resistance to acaricides, this usually happens much slower if pesticides are used strategically. To slow the development of resistance, several measures can be implemented: 

• Minimise the number of acaricide treatments.
• Assess tick diversity and acaricide resistance at the farm level and monitor it regularly. The study found that acaricide resistance was highly variable across South Africa, likely due to different farm management practices; hence it should be assessed at the farm level.
• Quarantine animals when transferring them to a new farm, ensuring they are free of ticks before releasing them.
• Rotate acaricides from different chemical classes, with a gap of at least two years between applications.

• Government veterinary services should raise awareness about acaricide resistance and provide support, particularly to under-resourced farmers. Establishing acaricide resistance testing laboratories would help monitor resistance and offer guidance to farmers.

Expert in parasitology

Dr Van der Mescht is particularly fascinated by the fact that most animals on earth follow a parasitic way of life. He graduated with a PhD in Conservation Ecology from the Department of Conservation Ecology and Entomology at Stellenbosch University in 2015, focusing on rodent parasites.

Career highlights include receiving the Wilhelm Neitz Memorial Scholarship in Parasitology from the Parasitological Society of Southern Africa (PARSA) for study abroad, and the Blaustein Centre for Scientific Cooperation Postdoctoral Fellowship in 2016 from Ben-Gurion University of the Negev, Israel, to conduct research on the experimental evolution of host specialisation. He also received the Claude Leon Foundation Postdoctoral Fellowship in 2019 to study the cat flea at Stellenbosch University’s Department of Botany and Zoology.

With over four years of experience in the industry at a contract research organisation, he has conducted more than 40 clinical studies for international pharmaceutical companies and published over 50 peer-reviewed scientific articles.

Making research visible, impactful, and relevant to society

Dr Van der Mescht recently published an article for The Conversation and participated in interviews with eNCA, Newzroom Afrika, and Cape Talk to discuss his research. “This effort aligns with the Vision 130 strategy of being a regionally engaged university and supports one of the key pillars of research development at the University of the Free State (UFS), which is to make our research visible, impactful, and relevant to society.”

He also highlighted the significance of popular science, noting that it helps scientists communicate their research to a broader audience, build their professional reputation, enhance their funding opportunities, and improve their research outcomes.

News Archive

Studies to reveal correlation between terrain, energy use, and giraffe locomotion
2016-11-18



More than half of giraffes in captivity in Europe are afflicted by lameness. This high prevalence represents an important welfare issue, similar to other large zoo animals.

According to Dr Chris Basu, a veterinarian at the Royal Veterinary College in the UK, giraffes in captivity are often afflicted by overgrown hooves, laminitis and joint problems. Diagnosis and treatment is limited by our understanding of anatomy and function, more specifically the locomotion of these animals. Although the giraffe is such a well-known and iconic animal, relatively little has been studied about their locomotor behaviour.

Dr Basu recently visited South Africa to do fieldwork on the locomotion of giraffes as part of his PhD studies under the mentorship of world-renowned Professor of Evolutionary Biomechanics, Prof John Hutchinson. This project is a joint venture between Dr Basu and Dr Francois Deacon, researcher in the Department of Animal, Wildlife, and Grassland Sciences at the UFS. Dr Deacon is a specialist in giraffe habitat-related research. 

Together Prof Hutchinson and Drs Deacon and Basu form a research group, working on studies about giraffe locomotion.

Wild giraffe population decrease by 40% in past decade

“Locomotion is one of the most common animal behaviours and comes with a significant daily energetic cost. Studying locomotion of wild animals aids us in making estimates of this energetic cost. Such estimates are useful in understanding how giraffes fit into ecosystems. Future conservation efforts will be influenced by knowledge of the energy demands in giraffes.

“Understanding aspects of giraffe locomotion also helps us to understand the relationships between anatomy, function and evolution. This is relevant to our basic understanding of the natural world, as well as to conservation and veterinary issues,” said Dr Deacon.

Locomotion study brings strategy for specialist foot care

On face value it seems as if foot disease pathologies are more common in zoo giraffes than in wild giraffes. “However, we need a good sample of data from both populations to prove this assumption,” said Dr Basu. 

This phenomenon is not well understood at the moment, but it’s thought that diet, substrate (e.g. concrete, straw, sand and grass) and genetics play a part in foot disease in giraffes. “Understanding how the feet are mechanically loaded during common activities (standing, walking, running) gives our research group ideas of where the highest strains occur, and later how these can be reduced through corrective foot trimming,” said Dr Basu.

Through the studies on giraffe locomotion, the research group plans to devise strategies for corrective foot trimming. At the moment, foot trimming is done with the best evidence available, which is extrapolation from closely related animals such as cattle. “But we know that giraffes’ specialist anatomy will likely demand specialist foot care,” Dr Basu said.

Studying giraffes in smaller versus larger spaces

The research group has begun to study the biomechanics of giraffe walking by looking at the kinematics (the movement) and the kinetics (the forces involved in movement) during walking strides. For this he studied adult giraffes at three zoological parks in the UK. 

However, due to the close proximity of fencing and buildings, it is not practical to study fast speeds in a zoo setting. 

A setting such as the Willem Pretorius Nature Reserve, near Ventersburg in the Free State, Kwaggafontein Nature Reserve, near Colesberg in the Karoo, and the Woodland Hills Wildlife Estate in Bloemfontein are all ideal for studying crucial aspects such as “faster than walking” speeds and gaits to measure key parameters (such as stride length, step frequency and stride duration). These studies are important to understand how giraffe form and function are adapted to their full range of locomotor behaviours. It also helps to comprehend the limits on athletic capacity in giraffes and how these compare to other animals. 

Drones open up unique opportunities for studying giraffes

The increasing availability of unmanned aerial vehicles (UAVs)/drones opens up unique opportunities for studying locomotion in animals like giraffes. Cameras mounted onto remotely controlled UAVs are a straightforward way to obtain high-quality video footage of giraffes while they run at different speeds.

“Using two UAVs, we have collected high definition slow motion video footage of galloping giraffes from three locations in the Free State. We have also collected detailed information about the terrain that the giraffes walked and ran across. From this we have created 3D maps of the ground. These maps will be used to examine the preferred terrain types for giraffes, and to see how different terrains affect their locomotion and energy use,” said Dr Deacon.

“The raw data (videos) will be digitised to obtain the stride parameters and limb angles of the animals. Later this will be combined with anatomical data and an estimation of limb forces to estimate the power output of the limbs and how that changes between different terrains,” said Dr Basu.


Related articles:

23 August 2016: Research on locomotion of giraffes valuable for conservation of this species
9 March 2016:Giraffe research broadcast on National Geographic channel
18 Sept 2015 Researchers reach out across continents in giraffe research
29 May 2015: Researchers international leaders in satellite tracking in the wildlife environment

 

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