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26 September 2019 | Story Leonie Bolleurs | Photo Leonie Bolleurs
Read More Prof Wijnand Swart PSHB
A small 2 mm beetle, known as the Polyphagous shothole borer (PSHB) kills and infects trees. South Africa is the largest geographical area in the world to be infested with this tree killer. Pictured here is Prof Wijnand Swart who is working with two neighbourhood associations in Bloemfontein to monitor the occurrence of the beetle in the city.

Ornamental trees are dying all over South Africa, and it is feared that certain fruit and nut trees are also in danger. This is cause for great concern, not only among ecologists, farmers, foresters, and landscapers, but for homeowners as well. In private gardens and on streets throughout the country, trees that are afflicted include English oak, Chinese and Japanese maples, boxelder, and sweetgum.
 
The cause of all this havoc is a small 2-mm beetle, known as the Polyphgous shothole borer (PSHB; Euwallacea fornicatus) that originates from Southeast Asia.

Working to find a solution

"Based on damage seen in the USA and Israel, there is significant danger of losing many of our ornamental trees as well as fruit and certain nut trees in South Africa,” says Prof Wijnand Swart, Professor of Plant Pathology and Discipline Head in the Department of Plant Pathology at the University of the Free State (UFS).

Cases of afflicted trees were reported from all provinces in South Africa, except for Mpumalanga. Countries such as Israel and the USA have also suffered great losses as a result of this beetle.  

Research is being conducted on the beetle and its associated fungus, Fusarium euwallaceae, in order to understand their relationship and hopefully find a solution to stop, or at least manage, the invasion of trees. To investigate the largest geographical outbreak of this beetle in the world, academics from seven universities in South Africa are working together with the Forestry and Agricultural Biotechnology Institute (FABI) at the University of Pretoria through a multi-institutional and multi-disciplinary research network. UFS researchers are part of this network.
 
Senior Lecturer in the UFS Department of Plant Sciences, Dr Gert Marais, is conducting research on the PSHB and its associated fungi, with the focus on pecan trees, in conjunction with the South African Pecan Nut Producers' Association. Cases of infected pecan-nut trees were reported in the Northern Cape as well as in Nelspruit. 
 
Prof Swart is working with entomologists in the UFS Department of Zoology and Entomology to find a biological control agent to parasitise the beetle. “I have already found one instance of a parasitic wasp associated with the beetle and will continue to search for more specimens during the coming summer,” he commented. 
 
Understanding the beetle

The first cases of infected trees were discovered in 2017 when Dr Trudi Paap, associated with FABI and the South African National Biodiversity Institute, conducted a survey of pests and diseases in and around National Botanical Gardens in South Africa. 
 
FABI has been studying the tree killer intensively to find out more about its life cycle. The term ‘polyphagous’ refers to the ability of the PSHB to infest many different tree species.

On their website, FABI states that an important distinction is being made between different types of infestations. “Reproductive host trees are trees that are infested by the beetle and where it successfully establishes a breeding gallery in which the fungus grows, where eggs are laid, and larvae develop into mature adults, thus completing its life cycle. The majority of reproductive hosts eventually succumb to the disease symptoms caused by the fungus.”
 
“Non-reproductive host trees are trees where the beetle attacks, penetrates, and inoculates the fungus, which then starts to grow in the sapwood. However, the beetle either leaves or dies without reproducing in these trees. The fungus can eventually kill or damage reproductive hosts, but many of the tree species on this list seem to be unaffected.”
 
Involving the community

The situation also provides an opportunity for communities to directly benefit from research conducted by tertiary institutions. Prof Swart is working together with two neighbourhood associations in Bloemfontein to monitor the occurrence of the beetle in the city and surrounding areas. 

He urges residents in the Mangaung Metro who find instances of infected trees, to report it to Duart Hugo (duarthugo99@gmail.com ), who is compiling a database of infected trees in the area. 
 
FABI advises homeowners to cut down heavily infested reproductive host trees. Should you decide to burn the wood, note that beetles will fly away when the wood becomes hot or when smoke appears. Do not burn infested trees in uninfected areas.

Other interesting material

News Archive

Space-based information plays vital role in disaster-risk reduction
2017-02-28

Africa is one of the continents most affected by disasters triggered by natural hazards. The result of climate change is a reality that affects every human being, whether it is extreme heat waves, cyclones, or the devastation of drought and floods. Climate change can provoke injuries or fatalities and affects the livelihoods of people in both rural communities and urban areas. It triggers damage and losses in various sectors of development, such as housing, road infrastructure, agriculture, health, education, telecommunications, energy, and affects routine economic processes leading to economic losses.

According to Dr Dumitru Dorin Prunariu, President of the Association of Space Explorers Europe, space programmes have become an important force defining challenges of the 21st century. “Space observation is essential for climate-change monitoring,” he said.

Dr Prunariu was the keynote speaker at a two-day symposium on climate resilience and water that was hosted by the Disaster Management Training and Education Centre for Africa (DiMTEC), at the University of the Free State (UFS). He participated in the Soviet Union’s Intercosmos programme and completed an eight day-mission on board Soyuz 40 and the Salyut 6 space laboratory, where he and fellow cosmonaut Leonid Popov completed scientific experiments in the fields of astrophysics, space radiation, space technology, space medicine, and biology. He is the 103rd human being to have travelled to outer space.

The focus of Dr Prunariu’s lecture was: Space activities in support of climate change mitigation and climate resilience.

Description: Dr Dumitriu Dorin Prunariu Tags: Dr Dumitriu Dorin Prunariu

Dr Dumitru Dorin Prunariu, the 103rd human
being in outer space and President of
the Association of Space Explorers Europe.
Photo: Charl Devenish

Space-based information, an extra eye that can detect a way out during disasters
“For governments to support communities affected by any disaster, precise and up-to-date information on its impacts is essential as a way to respond in a timely and effective way,” said Dr Prunariu.

Space-based information (derived using Earth observation, global navigation satellite systems, and satellite communications) can play a vital role in supporting disaster-risk reduction, response, and recovery efforts, by providing accurate and timely information to decision-makers.

“With space-based information, disaster management teams will be able to take note of recently established roads that may not appear in typical maps produced by National Geographic Institutes, but which could be used as emergency evacuation routes or as roads to deliver humanitarian assistance to those who require it in remote areas."

Space-based tools help decision-makers to improve planning
“Space-based tools and spatial data infrastructure is also crucial for policy planners and decision-makers in increasing the resilience of human settlements. Using geographic data and information collected before the occurrence of major disasters in combination with post-disaster data could yield important ideas for improved urban planning, especially in disaster-prone areas and highly-populated regions.

“In the recovery process, information on impact is used by governments to provide assistance to those affected, to plan the reconstruction process, and to restore the livelihoods of those affected,” said Dr Prunariu.

“Space observation is
essential for climate-
change monitoring.”

The symposium was attended by representatives from Liberia, Nigeria, Kenya, Ghana, Namibia, and Zimbabwe, with various international scientists from Europe imparting their expert knowledge on water and global resilience. The presence of these international experts strengthened global networks.

It isn't important in which sea or lake you observe a slick of pollution, or in the forests of which country a fire breaks out, or on which continent a hurricane arises, you are standing guard over the whole of our Earth. - Yuri Artyukhin: Soviet Russian cosmonaut and engineer who made a single flight into space.

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