Pest Euwallacea fornicates
Polyphagous shot-hole borer
08 October 2021
East Fremantle, Western Australia
The Western Australia Department of Primary Industries and Regional Development (DPIRD) is responding to the detection of an exotic beetle, Polyphagous Shot-Hole Borer (Euwallacea fornicatus) in a 30-year-old backyard maple tree in East Fremantle. Polyphagous shot-hole borer is a tiny beetle (about 2 mm in length) that bores into living trees which can result in tree death. It is considered both an agricultural and environmental pest with more than 400 host species including horticulture production, native and amenity trees.
This is the first time that Polyphagous Shot-Hole Borer has been detected in Australia. Further surveillance in the East Fremantle and Fremantle areas is underway by DPIRD to determine its spread. DPIRD is working closely with the local plant industries, including GIA and NGIWA, councils and the community to conduct the surveillance and tracing activities.
If the borer spreads beyond urban amenity trees, it could impact the production nursery, fruit, and nut tree industries, as well as the forestry industry. In South Africa where it is present, the removal and treatment of dead trees in urban areas has caused significant economic impacts.
The Consultative Committee on Emergency Plant Pests met on 5 October 2021 to discuss this detection. It was agreed that Polyphagous shot-hole borer and the fungus it feeds on, is an emergency plant pest as categorised under Emergency Plant Pest Response Deed. The committee agreed that more information is needed in terms of its spread, before they can make a decision on whether it can be eradicated.
A Quarantine Area Notice is in place to help contain the spread of the borer in WA. Containerised plants, trees, mulch and wood cannot be removed from the quarantine area. The quarantine area applies to parts of the suburbs of Fremantle, East Fremantle, North Fremantle, Palmyra and Bicton for an initial period of six months. A detailed map is available at agric.wa.gov.au/borer.
Residents in East Fremantle have been advised to check their trees for signs of borer damage and wilting and to not remove wood or green waste material from their property unless it is through an approved council collection. If you suspect borer damage, report it to DPIRD through their MyPestGuide® Reporter app or call the Exotic Plant Pest Hotline on 1800 084 881.
Polyphagous shot-hole borer
The adult female beetles are 2mm long and tunnel into the tree’s stems and branches, causing damage and dieback, from as small as 10mm in diameter up to large trucks and branches. They spread with the movement of infested trees, firewood and green waste material. After mating, female borers disperse to look for suitable host trees and may fly up to 400 metres.
Polyphagous shot-hole borer has a symbiotic relationship with the fungus Fusarium euwallaceae, which is used as a food source for the beetle and its larvae. Fungus samples were found with the borer in WA. Additional testing is underway to confirm if it is the symbiotic fungus, Fusarium euwallaceae. The fungus disrupts water and nutrient movement within the vascular system of susceptible trees, causing the disease Fusarium dieback. Symptoms are wilting and dieback of tree branches and leaves, often starting in the upper canopy.
What to Look for
The adult beetles and their larvae can be hard to spot as they spend most of their lives inside a tree; however, there are several symptoms that indicate the borer could be present including:
o Multiple entrance holes, up to 2mm diameter or the size of the tip on a ballpoint pen, on the trunk or branches.
o Frass (white) extruding from the tree and crystalline foam which look like sugar volcanoes exuding from the entry holes.
o Thick resin or sap on the tree’s branches or trunk. This can sometimes push the beetle out of the gallery.
o Dark brown to black staining of the wood around entrance holes.
o Wilting and dying branches and eventually tree death. Symptoms usually start in the upper canopy. Spring and autumn are when the beetle is most likely to be seen, as it moves to new trees.
Report and submit samples
All growers are encouraged to report any signs of borers in host plants to the Exotic Plant Pest Hotline on 1800 084 881. Instructions will be given on how to collect and submit samples for identification. Your cooperation will assist in delimiting the spread of this unwanted new pest species.