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31 October 2021 | Story Elsabé Brits
Grassland

In the vast, flat grasslands of South Africa a host of magnificent plant and animal species flourish, but not all of them are large. Insects and spiders share the landscape, and they are sometimes the uncelebrated heroes of a fragile ecology.

Walking through grasslands one often ignores what is under our feet, but these creatures are vitally important for the wellbeing of any ecosystem.

Grasslands are the dominant vegetation in the central parts of the country, covering most of the Free State and Gauteng and large parts of the North West, Mpumalanga, KwaZulu-Natal and the Eastern Cape, explains Prof Charles Haddad from the Department of Zoology and Entomology in the Faculty of Natural and Agricultural Sciences at the University of the Free State (UFS).

Insects fulfil a myriad of ecosystem functions and deliver crucial services in grasslands. They are the most important group of pollinators, such as bees, flies, and beetles, and are critical to the breakdown of plant and animal waste, especially flies and beetles. They are predators and parasites of other invertebrates, especially spiders, beetles, wasps and flies. The more species in an ecosystem, the greater the number of interacting organisms that can contribute to food webs.

Unfortunately, grasslands are the most threatened biome in South Africa, largely as a consequence of historical agricultural expansion of crop and livestock farming. More recently, urban development, invasive plants and silviculture have impacted on the remaining natural grasslands.

“Little is known about the impact of these activities on terrestrial biodiversity. The presumption is that the destruction and fragmentation of natural grassland reduces the natural vegetation available to indigenous organisms. This creates problems for insects to find suitable plants to feed on, which has a negative impact on their predators and parasites.

“Most anthropogenic influences affect indigenous biodiversity negatively, with very few exceptions. Generally, it is exotic invasive species that benefit the most from disturbance, habitat changes or destruction,” says Prof Haddad.

Spiders

More than 900 species of spiders have been recorded in our grasslands and some 2 300 in the country. Spiders are predators of other invertebrates, especially insects, and play an important role in the natural control of their populations.

They are very resilient to disturbance but are susceptible to chemicals used on crops, the effects of alien plants, and competition with exotic spider species, says Prof Haddad.

Among the interesting spider species one can find in grasslands is a rich diversity of trapdoor spiders, which live in burrows in the ground. Many of them have narrow associations with specific soil types and are often good bioindicators for conservation management.

Some plant-dwelling spiders are uniquely adapted to living on grasses and have slender, pale bodies to camouflage themselves on the stalks of grasses. In contrast, tree-dwelling spiders are often brown with tubercles on their bodies to blend in with the bark of trees to help them ambush their prey, says Prof Haddad.

Termites

Termites are some of the most populous animals on Earth, and the effects they have are most profound in the grasslands. Termites are one of the few animals that can break down cellulose from dead wood and grass. This is made possible through their symbiotic association with tiny microorganisms in their alimentary canal, such as protozoans and bacteria. The microorganisms secrete the enzyme cellulase, which the termites cannot produce themselves, allowing for the breakdown of cellulose in the ingested plant material and the release of the component nutrients for use by the termites. Therefore, these insects play an integral role in the reintroduction of nutrients from the dead plants into the soil.

This enables them to utilise the molecules in the grass that would have otherwise been inaccessible. Their faeces, therefore, contain broken-down nutrients that the roots of plants can absorb.

Many termite species live in underground nests that are great in aerating the soil. Others build large mounds which are extensions of the nests above the soil surface. These mounds, particularly those of the snouted harvester termites, are a familiar feature in most grassland landscapes in the country. These nests and mounds also offer shelter to other organisms, such as spiders, scorpions, lizards, snakes, millipedes, and various insects.

Termites are an important food source for enigmatic animals such as the aardvark and aardwolf, as well as some spiders and beetles, says Prof Haddad. 

Mosquitoes 

Liezl Whitehead, a master’s student in the Department of Zoology and Entomology at the UFS, explains the role of how even mosquitoes are essential.

Mosquitoes are vitally integrated into the ecosystem even as larvae, where they feed on aquatic microorganisms, thereby affecting species interactions and ecosystem dynamics within the aquatic habitat.

Adult mosquitoes feed on nectar as their main food source, and in the process also serve as plant pollinators. Many female mosquitoes do, however, require a blood meal for egg production, where they then transmit a multitude of pathogens. Interestingly, these pathogens play a vital role in the ecosystem, where they help to regulate host population sizes, thereby maintaining the integrity of the ecosystem.

“In recognising the significance of all forms of life, one also realises that mosquitoes play an essential role in the life cycle of numerous other organisms, including protozoans [single-celled microscopic organisms], nematodes [often referred to as roundworms, but they are not closely related to true worms], and mites that depend on mosquitoes for their development and dispersal.

The abundance and widespread nature of mosquitoes contributes to their significant role in the grassland food chain, where the larvae are consumed by countless aquatic organisms, including insects, fish and amphibians. The adults are consumed by a multitude of arthropods and vertebrates, including dragonflies, birds and bats.

“Their elimination from the ecosystem would thereby impact multiple processes within the ecosystem, affecting food webs, pollination and the presence of many other associated organisms,” Whitehead adds. 

A vital food source, urgent protection needed

Prof Liesl van As, Head of the Department of Zoology and Entomology at the UFS says that although the Grassland biome covers an area of 339 237 km2, less than 2% is formally protected. In 2004, the National Spatial Biodiversity Assessment (NSBA) identified the Grassland biome as the most threatened habitat, with more than 30% already irreversibly transformed. A year later, the Grassland Biodiversity Spatial Priority Assessment identified 37% of the land as being important for conservation and suggested that 12% needs to be under formal protection by 2028.

Most of the South African grassland literature refers to the almost 400 plant species, the 34 endemic mammals, and the dozen or so globally threatened bird species, with almost no mention to representatives of the Arthropoda (including spiders, termites and mosquitoes).

Invertebrates are the main components of faunal diversity in grasslands, playing substantial roles in ecosystem processes, including nutrient cycling, pollination, and being a vital food source in food webs (Die een se dood is die ander een se brood).

“These invertebrate communities are heavily dependent on plant diversity and production within a given ecosystem, but for some reason, they don’t get the full recognition and attention compared to the larger animals. Maybe it is because they are not so visible due to their smaller size?

“A visit to www.grasslands.org.za and the Grassland Society of Southern Africa draws our attention towards the fact that although progress has been made in the awareness of the sensitivity of grassland habitats, gaps still exist concerning the biodiversity of the remaining natural fauna. To follow up on this, I am of the opinion that when it comes to invertebrates, such as the spiders, termites and mosquitoes we are now writing about, knowledge and public awareness (citizen science) is contributing to reducing this gap” says Prof Van As.

According to her, in their department, a number of colleagues from Animal Behaviour, Arachnology, Nematology, Applied Agricultural Entomology, Environmental Entomology and Dipterology, to name a few, have been involved in research projects for the past few decades, with a focus on the grassland area, closer to home.  Through their effort and contributions, they are making a scientific difference. 

News Archive

Honorary doctorate to Archbishop Emeritus Desmond Tutu attracts wide attention
2011-01-27

Archbishop Emeritus Desmond Tutu after receiving his honorary doctorate in Theology at the UFS.
- Photo: Hannes Pieterse

 

The University of the Free State (UFS) awarded an honorary doctorate to Archbishop Emeritus Desmond Tutu on Thursday, 27 January 2011. The graduation ceremony, which was attended by guests from across the country marks a milestone in the history of the university.

Amongst the guests were the ambassador of the USA to South Africa, Mr Donald Gips; the British High Commissioner to South Africa, Dr Nicola Brewer; members of the local government; Ms Barbara Hogan, former Minister of Public Works and the daughters of Bram Fischer, Ruth Fischer-Rice and Ilse Fischer-Wilson. Friends of Dr Tutu, Dr Ahmed Kathrada, Ms Barbara Hogan and Dr Allan and Ms Elna Boesak also attended the occasion.
 
The UFS also received a message of congratulations from the Deputy President of South Africa, Mr Kgalema Motlanthe. “The choice to honour this exemplar of virtue to which most of the world still look for direction as it buckles under social, political and economic difficulties is laudable in all respects,” he said.
Prof. Jonathan Jansen, Vice-Chancellor and Rector of the UFS, said: “We honour a great son of South Africa who made a tremendous contribution to peace, reconciliation and justice in South Africa and in the world.
 
“There were times when few of us thought apartheid would end in our lifetime, yet you stood as a rock reassuring us, not about a black future, but about our common future. For this reason, Arch, we would not miss this opportunity to honour you for any reason whatsoever.
 
“You, Sir, are a Jew among Muslims, a Christian among Hindus, a Catholic among Anglicans, a bridge-builder among all of us. That is why we love you; because you look deeper and see further than all of us.”
 
According to Prof. Francois Tolmie, Dean of the UFS’s Faculty of Theology, the university honours Dr Tutu for his contribution as theologian – through his teaching and the books he wrote – as well as for the role he played in bringing about reconciliation in South Africa as well as in the rest of the world. The university also honours Dr Tutu as a moral and spiritual leader who never sacrificed his integrity as a Christian.
 
Apart from being a church leader and a leading world figure, Dr Tutu is the author of several books and also held a number of teaching posts at various tertiary institutions.
 
In 1984, he received the Nobel Peace Prize for his role as a unifying leader figure in the campaign to abolish apartheid in South Africa. A further highlight in his career was his election as Archbishop of Cape Town in 1986. He was the first black African to serve in this position, which placed him at the head of the Anglican Church in South Africa.  
 
Many South Africans also remember the role he played when President Nelson Mandela appointed him in December 1995 to chair the Truth and Reconciliation Commission, which was established to investigate human rights violations during the apartheid era. The Archbishop guided the nation in the process of choosing forgiveness over revenge and in so doing set a historic international precedent.   
 
In 1996, he retired as Archbishop of Cape Town but continues to speak out in favour of human rights, equality and social justice in South Africa and throughout the world.
 
In August 2009, President Barack Obama presented him with the Medal of Freedom, the United States of America’s highest civilian honour. Dr Desmond Tutu is recognised around the world as a moral leader committed to the human rights of all people.
 
Today he is chairman of The Elders, a group of world leaders who, in view of their integrity and leadership, are equipped to deal with some of the world’s most pressing problems.
 
Prof. Tolmie says: “It is often asked how Dr Tutu could have achieved all this in the span of one lifetime. Some people would refer to his warm personality or his humanness, his deep sense of humility or his wonderful sense of humour. Probing a little deeper, however, one is struck by Dr Tutu’s deep relationship with God. He is known as a man of faith, a man of prayer. He lives his life coram Deo, in the presence of God.”
 
Dr Tutu also lead the introduction ceremony of the UFS’s International Institute for Studies in Race, Reconciliation and Social Justice.
 
 
Media Release
27 January 2011
Issued by: Lacea Loader
Director: Strategic Communication (actg)
Tel: 051 401 2584
Cell: 083 645 2454
E-mail: news@ufs.ac.za
 

 

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