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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

Inaugural lecture: Prof André Pelser
2004-06-04

Tendencies and changes in the South African population structure in future decades.

Within the next five years South Africa will for the first time in the past century enter a period where the death rate will exceed the birth rate, largely due to the impact of HIV / AIDS.

According to sociologist Prof André Pelser, sociologist at the of the University of the Free State’s (UFS) Department of Sociology, the death rate exceeding the birthrate is only one of three demographic trends which will fundamentally change South Africa’s population structure in the following decades.

He was speaking at the UFS in Bloemfontein during his inaugural lecture as professor this week.

Prof Pelser said that according to some models the South African population will decrease within the next five decades by between 10 and 26 percent.

A second important trend which will impact on the population structure is the progressive ageing of the population.

He said the group above 65 years is the only age category in the South African population which will witness sharp increases in the next few decades.

In the next 50 years, the group younger than 15 years will reflect a decrease of 39% and those older than 65 years in South Africa will increase by approximately 110% in the next two decades.

“The systematic “greying” of the South African population will create the same economic and welfare issues as those with which governments in some more developed countries are already grappling,” said Prof Pelser.

A third trend affecting the South African population structure is the constant decrease in life expectancy.

Life expectancy at birth for the total population is projected to decrease from approximately 62 years at the beginning of the 1990’s to 43 years in 2015-2020, with sharp differences between the various population groups.

These tendencies and changes to the South African population structure have serious implications, he said.

For example, he said, the reduction in life expectancy could compromise national development objectives.

“It is estimated that more than a quarter of the economically active population will be infected with HIV by 2006,” said Prof Pelser.

The increase in the population, in age category 65, will place a financial burden on government and the economically active sector.

“Especially worrying is the fact that ever-increasing proportions of the state budget will be allocated to health and welfare services and this at the expense of other priorities like education, infrastructure, criminal justice system and trade and industry, to name but a few,” he said

“A comprehensive and integrated strategy is thus vitally important in addressing the overarching issues caused by changes in the population structure,” said Prof Pelser.

 

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