Shothole Borerbeetle and Shothole Borer Fungus

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

Posted on 08 April, 2019 08:58 by