Farm Forestry New Zealand
PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
Polyphagous shot hole borer detected in Western Australia
Scion is the leading provider of forest-related knowledge in New Zealand
Formerly known as the Forest Research Institute, Scion has been a leader in research relating to forest health for over 50 years. The Rotorua-based Crown Research Institute continues to provide science that will protect all forests from damage caused by insect pests, pathogens and weeds. The information presented below arises from these research activities.
From Forest Health News 306, March 2022
The polyphagous shot-hole borer (PSHB) (Euwallacea fornicatus) has recently been detected in Perth, Australia. Native to Southeast Asia, this tiny beetle has spread to North and Central America, Israel, South Africa, Europe (Italy, Netherlands, Germany and Poland – greenhouses), Papua New Guinea, Fiji and, and now Australia (Perth) where it is under eradication.
This damaging pest infests more than 400 plant species, mostly woody species and carries a few known symbiotic fungi, including the damaging Fusarium euwallaceae. Fusarium euwallaceae infects the vascular tissue of a susceptible tree and can cause dieback and death. The beetle attacks stressed trees primarily but can also attack healthy trees. Plant hosts are divided into two categories: reproductive and non-reproductive. This interaction is dependent on how successful PSHB’s fungal symbiont, symbionts colonise the host's tissue. the host’s tissue. In a reproductive host, the fungus will establish well allowing the beetle to thrive, while in a non-reproductive host it will not and the beetle does not complete its lifecycle; however, symptoms may develop.
This beetle and its fungus can attack many globally important commercial species, such as avocado, macadamia, acacia, and eucalyptus. It has been reported from pine but only in one instance, in a single stressed pine tree where the beetle, eggs and larvae were found.
Thankfully, there is a pheromone, quercivorol, available for use with traps to help detect and monitor PSHB. However, the beetle remains difficult to eradicate and manage. Any infested wood needs to be cut, removed and destroyed, or treated. Chemical applications of standing trees can be useful on a small scale and biological control options are also being sought.
Image: Samantha Bush (FABI)
While it is unlikely that PSHB will routinely attack standing and cut conifers, logs should be inspected and if infested, treated before export. Timber from known reproductive hosts will need to be inspected and treated before being used or transported domestically as the beetle is readily spread by the movement of wood and wood products. Movement of infested live plants should be restricted, especially from nurseries.
The economic impacts of this pest can be severe. In Israel, PSHB infestations have led to a 100% yield loss in avocado in some areas. In South Africa, the unmitigated baseline social cost of the pest is predicted to be around $27.12bn or 1% of South Africa’s GDP, due to impacts on urban trees. Of concern is a confirmed finding of it from a Sophora spp. in Perth, the same genus as iconic Kowhai trees in New Zealand.
Darryl Herron, Scion
Image: Darryl Herron
Image: Masi Losi
This information is intended for general interest only. It is not intended to be a substitute for specific specialist advice on any matter and should not be relied on for that purpose. Scion will not be liable for any direct, indirect, incidental, special, consequential or exemplary damages, loss of profits, or any other intangible losses that result from using the information provided on this site.
(Scion is the trading name of the New Zealand Forest Research Institute Limited.)
NZFFA on facebook