Biosecurity Alert Update #3 - Euwallacea fornicatus 
(Polyphagous shot-hole borer)

Situation

The Western Australia Department of Primary Industries and Regional Development (DPIRD) continues to respond to detections of an exotic beetle, polyphagous shot-hole borer (Euwallacea fornicatus). Polyphagous shot-hole borer is a tiny beetle (approx. 2mm) that bores into living trees which can result in tree death due to the transmission of a symbiotic species of Fusarium that infects the vascular system of host trees.

Polyphagous shot-hole borer is considered both an agricultural and environmental pest with more than 400 host species including horticulture production, native and amenity trees. Initially detected in East Fremantle, Western Australia WA) in August 2021, this is the first time it has been detected in Australia.

A Quarantine Area was initially established around East Fremantle and Fremantle to prevent further spread of the pest, and to allow for urgent ongoing surveillance activities. On 16 November 2021, an expanded Quarantine Area came into effect covering 17 Western Australian local government areas. See detailed map here.

As of 16 November 2021, there were 21 confirmed infested premises. This includes 14 private premises, three parks and four street trees. To date, positive samples have been taken from numerous species of trees including:

• Box elder maple (Acer negundo)
• Coral tree (Erythrina sp.)
• Sophora (Sapindus sp.)
• Poinciana (Delonix regia)
• Mango (Mangifera indica)
• Sea hibiscus or cotton wood (Talipariti tiliaceum, synonym: Hibiscus tiliaceus).

Trees in which the beetle can breed and multiply are referred to as reproductive host trees. Reproductive hosts trees include maple, oak, plane, coral tree, avocado and willows. Non-reproductive host trees are attacked by the beetle, but the beetle does not breed in these trees and does not establish galleries, also called tunnels. Non-reproductive host trees include eucalyptus, citrus and olives.

The Consultative Committee on Emergency Plant Pests met in October and November 2021 to discuss this detection. This committee recommended that the polyphagous shot-hole borer and the fungus associated with it are emergency plant pests as defined by the Emergency Plant Pest Response Deed. The committee agreed that more information is needed in terms of its current distribution before they can make a recommendation on the technical feasibility of eradication.

DPIRD is working closely with the local plant industries (e.g., NGIWA & GIA), councils and the community to conduct the surveillance and tracing activities. If the borer spreads beyond urban amenity trees, it could impact the nursery, fruit, and nut tree industries. It may also have potential impacts on the forestry industry.

All growers are encouraged to report any signs of borers on 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.

For further information email John McDonald, GIA National Biosecurity Manager : john.mcdonald@greenlifeindustry.com.au

Developed by the GIA National Biosecurity & Sustainable Plant Production Program Team 2021