First conformation of the presence of the Polyphagous Shot Hole Borer beetle and its fungus in the City of Cape Town Metropolitan Area
(lightly edited press release: 3 April 2019)

This officially confirms the presence of the invasive Polyphagous Shot Hole Borer beetle (PSHB, Euwallacea whitfordiodendrus) for the first time within the boundaries of the City of Cape Town Metropolitan area. We were informed of a possible infestation in the suburb of Somerset West by Mr Phumudzo Ramabulana from the City of Cape Town and Mr Paul Barker from Arderne Gardens on the 8th of March 2019. Mr. Elmar van Rooyen, a MSc student from Stellenbosch University currently working on the beetle for his thesis, collected samples from infested Liquid Amber and London Plane trees for laboratory analyses. The identity of the beetle and its symbiotic fungus was confirmed using morphological and DNA sequence analyses, and comparisons to the extensive database at the Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria.

The PSHB beetle is devastating insect pest that with its symbiotic fungus Fusarium euwallaceae, can kill a wide range of native and exotic tree hosts. It is currently causing immense damage in many other parts of the country and will likely be a significant threat to urban, agricultural and native trees in the City of Cape Town Metropolitan area and surrounds. Based on our experience with the PSHB invasion in George, Knysna, and other urban areas, trees like English Oaks are particularly susceptible and suffer from high mortality rates.

The seemingly low current infestation levels in the area indicates that this is likely a very recent invasion, but the species is capable of rapid reproduction and may also spread quickly through human mediated transport (particularly the movement of infested wood). Because of this, it is our opinion that effort should be made to extensively survey the suburb to determine the current area of extent of infestation. All infested trees, particularly those known to be reproductive hosts (see other News Items here), should be removed in an attempt to eradicate the pest and minimize its economic, social and environmental impact.

We sincerely hope that this information will bolster future decision-making processes for collaborative research and management endeavors. For any further information, please do not hesitate to contact us.

Prof. Francois Roets
Department of Conservation Ecology and Entomology, Stellenbosch University, Stellenbosch
fr@sun.ac.za
Prof. Z. Wilhelm de Beer
Forestry & Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria
Wilhelm.debeer@fabi.up.ac.za

Polyphagous Shot Hole Borer (Euwallacea whitfordiodendrus) and Shothole Borer Fungus (Fusarium euwallaceae - also known as Fusarium Dieback)

The Polyphagous Shot Hole Borer (PHSB) is an Ambrosia Beetle native to Southeast Asia.

It was first detected in southern Africa on London Plane Trees in the KwaZulu-Natal NBG, Pietermaritzburg. It has since been confirmed - as of early 2019 - from:

• Durban,
• Hartswater,
• Bloemfontein,
• George,
• Knysna, &
• Johannesburg.

The Shot Hole Borer Beetle has a symbiotic relationship with the Shothole Borer Fungus which it farms as a food for both itself and its grubs. It is the fungus that causes the most damage and dieback to susceptible trees. These may show minor symptoms from discoloration around the holes, to major symptoms such as branch dieback and death of the entire plant.

The Shot Hole Borer Beetle bores into a wide range of exotic and indigenous trees in both man-made and natural habitats. However, the beetles are unable to survive in many species that they bore into. Many of these trees do succumb though to the fungus infection. In tree species that are resistant to the fungus, the beetles will starve.
The reproductive hosts of Shot Hole Borer Beetle include:
Avocados,
Castor Beans,
Coraltrees,
Oaks,

Maples, &
Willows,

(see the full list here: www.fabinet.up.ac.za/index.php/research/7)
Please pay attention to these indigenous species as they have been infected in other parts of the world:
Cussonia (Cabbage Trees),
Calpurnia (Calpurnias),
Diospyros (Monkey Plums),
Erythrina (Coral Trees)
Schotia (Boerboons),
Melianthus(Kruidjie-roer-my-nie),
Cunonia capensis (Rooiels),
Nuxia floribunda (Forest Elder), &
Bauhinia (Orchidbushes)*.
(*resistant to the fungus).
Local crops susceptible include: Avocado, Macadamia Nut, Pecan Nut, Peach, Orange & Grapes.
Ornamental particularly susceptible include: some Maples, Hollies, Wisterias, Oaks & Camellias.

Beetles are distributed by movement of infected wood for firewood, packing, timber or curios, as well as the removal of dead and dying trees. Infected wood should never be transported and should be destroyed (by burning) as soon as possible. Chipping, composting and solarisation are also commercial options to reducing spread.

Surveys to monitor the spread of the Shot Hole Borer Beetle are underway. You can help detect infections by looking out for symptoms and photographing and reporting them prompty on iNaturalist.

Resources:

Basic information: https://www.fabinet.up.ac.za/pdf/PSHB_information_sheet.pdf
Beetle pics: https://www.fabinet.up.ac.za/pdf/PSHB_beetle_life_stages2.pdf
Symptoms: https://www.fabinet.up.ac.za/pdf/PSHB_symptoms2.pdf
Poster - symptoms: https://www.fabinet.up.ac.za/pdf/PSHB_external_symptom_types.pdf
Details: https://www.fabinet.up.ac.za/index.php/pshb

How to document: https://www.fabinet.up.ac.za/pdf/PSHB_how_to_photograph3.pdf

How to sample: https://www.fabinet.up.ac.za/pdf/PSHB_how_to_sample3.pdf

https://www.capetowninvasives.org.za/shot-hole-borer

from: Fact Sheet (Updated April 2018) - https://www.fabinet.up.ac.za/images/groups/ARP/ARP-Website-Fusarium-dieback-Fact-sheet-March-2018.pdf
(*by Noëlani van den Berg, Avocado Research Programme (FABI), University of Pretoria)

Euwallacea cf. fornicatus (Polyphagous Shothole Borer) is an Ambrosia Beetle native to Asia that has a symbiotic relationship with species of Fusarium fungus - including the pathogen Fusarium euwallaceae.
This fungus is responsible for Fusarium Dieback in Israel, California and Florida

The beetle carries spores within a special fungal pouch in its mandibles. Adult females burrow into trees and deposit the fungi to establish brood galleries. The fungus proliferates on the gallery walls and is grazed by both larvae and adult beetles. The fungal threads invade the wood tissues, causing necrosis of the cambium, resulting in dieback and death of some plants.
Some 200 trees are attacked by the beetle and fungus, although only about half support fungal growth, and only about a third of those supporting the fungus can be used by the beetles to reproduce.

Symptoms vary a lot, depending on hosts and levels of infection. The beetle itself is very small and hard to see. Their galleries penetrate 10-40 mm into the wood, and usually have several exit holes (with "sugar volcanos") on infested trees. Females are black and 1.8-2.5 mm long and males are brown and 1.5 mm long.

Hosts in South Africa include
Avocado (Persea americana),
Box Elder (Acer negundo),
Castor Bean (Ricinus communis),
Oak (Quercus spp.),
Citrus (Citrus spp.),
Tea (Camelia sinensis) and
London Plane (Platanus x acerifolia).

Less suitable hosts include Litchi, Mango and Cacao.
Affected fruits include:
Macadamia Nut (Macadamia integrifolia),
Pecan (Carya illinoinensis),
Peach (Prunus persica) and
Grape (Vitis vinifera)

Native species affected include:
Cabbage Tree (Cussonia spicata;
Common Calpurnia (Calpurnia aurea),
Monkey Plum (Diospyros lycioides),
Dwarf Coraltree ( Erythrina humeana)
Common Coraltree (Erythrina lysistemon),
Short Boerbean (Schotia brachypetala),
Honeyflower (Melianthus major),
Red Alder (Cunonia capensi),
Forest Alder (Nuxia floribunda) and
Red Orchid Bush (Bauhinia galpinii).

Please report any instances on iNaturalist.

Further reading:
https://www.fabinet.up.ac.za/publication/pdfs/3351-paap_et_al_2018_austr_pl_path.pdf
The polyphagous shot hole borer (PSHB) and its fungal symbiont. Fusarium euwallaceae: a new invasion in South Africa
Trudy Paap & Z. W. de Beer & D. Migliorini & W. J. Nel & M. J. Wingfield
Australasian Plant Pathology https://doi.org/10.1007/s13313-018-0545-0

.