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Rising tick pesticide resistance threatens South Africa’s cattle industry

14 August 2024 | Story Martinette Brits | Photo Supplied

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

Africa's Black Rhino conservation strategy must change

2017-07-10

The black rhino is on the brink of extinction. The study that was
published in the Nature Scientific Reports reveals that the
species has lost an astonishing 69% of its genetic variation.
Photo: iStock

The conservation strategy of the black rhino in Africa needs to change in order to protect the species from extinction, a group of international researchers has found. The study that was published in the Nature Scientific Reports reveals that the species has lost an astonishing 69% of its genetic variation.

South African researchers took part
The researchers, which included local researchers from the National Zoological Gardens of South Africa (NZG), have highlighted the fact that this means the black rhino is on the brink of extinction. "We have found that there is a decline in genetic diversity, with 44 of 64 genetic lineages no longer existing," said Prof Antoinette Kotze, the Manager of Research and Scientific Services at the Zoo in Pretoria. She is also affiliate Professor in the Department of Genetics at the University of the Free State and has been involved in rhino research in South Africa since the early 2000s.

DNA from museums and the wild
The study compared DNA from specimens in museums around the world, which originated in the different regions of Africa, to the DNA of live wild animals. The DNA was extracted from the skin of museum specimen and from tissue and faecal samples from animals in the wild. The research used the mitochondrial genome.

"The rhino poaching ‘pandemic’
needs to be defeated, because
it puts further strain on the genetic
diversity of the black rhino.”

Ability to adapt
Dr Desire Dalton, one of the collaborators in the paper and a senior researcher at the NZG, said the loss of genetic diversity may compromise the rhinos’ ability to adapt to climate change. The study further underlined that two distinct populations now exists on either side of the Zambezi River. Dr Dalton said these definite populations need to be managed separately in order to conserve their genetic diversity. The study found that although the data suggests that the future is bleak for the black rhinoceros, the researchers did identify populations of priority for conservation, which might offer a better chance of preventing the species from total extinction. However, it stressed that the rhino poaching ‘pandemic’ needs to be defeated, because it puts further strain on the genetic diversity of the black rhino.

Extinct in many African countries
The research report further said that black rhino had been hunted and poached to extinction in many parts of Africa, such as Nigeria, Chad, Cameroon, Sudan, and Ethiopia. These rhino are now only found in five African countries. They are Tanzania, Zimbabwe, Kenya, Namibia, and South Africa, where the majority of the animals can be found.

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