The Curtin University Breakthrough: Modeling the PSHB Invasion Risk

A groundbreaking study from Curtin University's School of Molecular and Life Sciences has put the nation on high alert. Led by Dr. Andrew Coates and co-authored by Professor Ben Phillips, the research titled 'Boring Beetles and Super Models: Mapping Potential Distributions of a New Invader' meticulously maps the potential spread of the polyphagous shot-hole borer across Australia. Published in the prestigious Journal of Biogeography, this work combines cutting-edge computational modeling with real-world data to forecast where this invasive pest could wreak havoc next. By simulating the beetle's full life cycle under varying climate conditions, the researchers have created a toolset that's already proving invaluable for biosecurity agencies nationwide.

What sets this study apart is its depth. Unlike previous efforts that relied on simplistic climate matching, Curtin's approach incorporates temperature-dependent population dynamics. Daily climate data from across Australia, coupled with detailed vegetation maps and biological parameters derived from global observations, were processed on the Pawsey supercomputing system. This allowed for precise predictions of population growth rates, dispersal mortality, and seasonal hotspots. The result? A clear warning that without intervention, PSHB could explode in population, doubling every 14 days in optimal conditions.

What Makes the Polyphagous Shot-Hole Borer So Dangerous?

The polyphagous shot-hole borer, or PSHB (Euwallacea fornicatus), is deceptively small—adult females measure just 2 millimeters long, about the size of a sesame seed. Native to Southeast Asia, this ambrosia beetle doesn't eat wood directly. Instead, it acts as a 'fungus farmer.' Females bore narrow tunnels, roughly 1.5 mm in diameter, into the trunks and branches of host trees, typically those with diameters over 10 cm. They introduce spores of the symbiotic fungus Fusarium euwallaceae, which grows to feed the larvae hatched from eggs laid in galleries within the tree.

This process starves the tree by clogging its vascular system, preventing nutrient and water transport. Symptoms include canopy dieback, small 'shot holes' on bark, and dark staining under the bark. Over 500 host species worldwide make PSHB truly polyphagous—feeding on diverse trees from urban ornamentals like jacaranda and liquidambar to agricultural crops such as avocados and potentially native eucalypts. In Australia, high-risk urban hosts include box elder maple (Acer negundo) and black locust (Robinia pseudoacacia), while farms face threats to horticultural production.

The beetle's biology amplifies the risk: parthenogenetic reproduction means females clone themselves, producing up to 20-30 daughters per brood, with multiple broods per year in warm climates. Step-by-step invasion: 1) Female locates suitable host via chemical cues; 2) Bores entry tunnel (1-2 days); 3) Cultivates fungus; 4) Lays eggs; 5) Larvae develop (3-4 weeks); 6) New adults emerge to disperse. This cycle can repeat rapidly, especially in summer.

From Fremantle to Perth Metro: The Current Invasion Front

First detected in Fremantle, Western Australia, in mid-2021, PSHB has since infested the Perth metropolitan area. By late 2025, authorities had inspected over three million trees across 135,000 properties, confirming infestations at hundreds of sites. More than 4,960 trees were removed, with an additional 1,178 pruned, and figures climbed to nearly 5,000 removals by mid-2025. The toll on Perth's urban canopy has been devastating, prompting a multi-million-dollar response from the Department of Primary Industries and Regional Development (DPIRD).

In June 2025, the National Management Group declared eradication unfeasible due to the beetle's entrenchment and logistical challenges. A shift to 'Transition to Management' ensued, establishing a quarantine zone around Perth. This includes movement controls on green waste, firewood, and nursery stock—key vectors for human-assisted spread. Despite these measures, detections continue, including in commercial avocado orchards, underscoring the urgency.

East Coast Australia in the Crosshairs: High-Risk Zones Identified

Curtin's modeling paints a stark picture for eastern states. The east coast, particularly Queensland and New South Wales, offers 'ideal conditions' for PSHB establishment. Brisbane, Sydney, and surrounding farmlands score high on suitability maps due to mild winters, humid summers, and abundant host trees. Melbourne and Adelaide also emerge as vulnerable, alongside agricultural heartlands where horticulture thrives.

Without human transport, natural spread is limited to 3-3.75 km per year via adult dispersal. However, hitchhiking in unseasoned firewood, mulch, or landscape plants could propel it thousands of kilometers overnight. Summer peaks beetle activity, making it the prime surveillance season. The study's maps, factoring in host availability, highlight urban bushland interfaces as invasion hotspots—precisely where cities meet farms.

Photo by mj tang on Unsplash

Urban Devastation: Impacts on Cities and Green Spaces

Perth's experience foreshadows east coast woes. Iconic parks like Kings Park have lost mature trees, eroding urban cooling, biodiversity, and aesthetics. PSHB targets beloved street trees, reducing property values and liveability. Globally, in California, millions in removal costs plague cities; Australia risks similar, with Perth's canopy already diminished.

Stakeholders like local councils lament the loss: restoration projects delayed, community backlash over tree felling. Yet, Curtin's model empowers proactive planting of resistant species and targeted injections—trials in City of Canning show promise with systemic insecticides.

For higher education professionals shaping green campuses, this underscores the need for biosecurity-savvy arboriculture. Universities like Curtin lead in training the next generation; aspiring experts can find opportunities in higher ed administration jobs focused on campus sustainability.

Agricultural Alarm: Farms Under Siege

Farming regions face existential threats. PSHB infests avocados (2500 ha in WA), macadamias, citrus, and pears—staples of east coast exports. Economic models predict escalating costs: without management, WA alone could see annual expenses hit A$6.8 million in 30 years. Nationally, unmitigated spread might mirror South Africa's projected 1% GDP loss (around US$27 billion).

• Avocado orchards: First WA commercial detection Dec 2025 signals vulnerability.
• Nut crops: Macadamias in QLD/NSW prime targets.
• Ornamental nurseries: Movement restrictions strain supply chains.

Growers urge vigilance; Curtin's predictive tools guide quarantine zoning. For careers in ag biosecurity, higher ed career advice on research assistant roles highlights pathways at institutions like Curtin.

Innovative Tools from Curtin: The PSHB Survey Planner

Responding to resource constraints, the team launched the PSHB Survey Planner app (try it here). Users input locations to view optimal survey windows—when adult emergence peaks. This democratizes surveillance, aiding councils, farmers, and citizens.

Funded by WA Premier’s Science Fellowship, it exemplifies university-government synergy. Professor Phillips notes: 'This gives agencies a powerful tool to plan surveillance and limit spread.'

Universities at the Forefront: Curtin's Role in Biosecurity Research

Curtin isn't alone; WAARC funds collaborative projects with Murdoch and UWA. Yet, this study spotlights population biology's power in invasion science. Dr. Coates' dual affiliation with Charles Darwin University bridges east-west knowledge.

Higher education drives solutions: fellowships, PhDs, labs training ecologists. Amid climate change accelerating invasions, demand surges for experts. Explore research jobs in higher ed or postdoc positions tackling threats like PSHB.

Photo by Harry Skillett on Unsplash

Stakeholder Perspectives and Challenges Ahead

Biosecurity officials stress prevention: 'Don't move firewood!' Farmers worry over exports; environmentalists fear natives. Challenges include detection (borers hidden), chemical resistance, and public compliance.

Solutions evolve: biocontrol trials, resistant cultivars, AI monitoring. Curtin's model tests strategies, forecasting slowdowns.

Future Outlook: Preventing a National Crisis

If contained, PSHB remains a WA issue. Spread east? Billions in losses, canopy collapse. Optimism lies in tools like Curtin's—proactive surveillance could avert disaster.

Individuals: Report suspects via MyPestGuide app; source certified plants. For academics, this era demands interdisciplinary talent. Check higher ed jobs, university jobs, career advice, rate my professor for mentors in biosecurity. Post a job at AcademicJobs.com to attract top talent.

For more, see the study at Journal of Biogeography.