Tools and knowledge to mitigate the potential spread of Xylella fastidiosa (Xylella) in Australia and New Zealand by understanding its potential vectors

Abstract

Australia is currently free from the devastating plant pathogen Xylella fastidiosa and its major known insect vectors. However, native Australian insects, particularly spittlebugs, could potentially spread this disease if it were introduced. This project set out to identify which Australian insects pose the greatest potential biosecurity risk. Through the native spittlebug Bathyllus albicinctus emerged as a likely candidate to spread Xylella in Australia, given its wide distribution, broad host range, and feeding behaviour.

Summary

Globally, Xylella fastidiosa has caused major economic losses in crops like grapevines, citrus, and olives. It spreads through the feeding activity of certain xylem-feeding insects, such as spittlebugs and sharp shooters. This project investigated whether native Australian species could act as potential vectors if Xylella was introduced.

What was done

The project was built around five major activities:

1. Multi-year insect surveillance in vineyards and orchards across southeastern Australia (grape, citrus, cherry, and olive).
2. Review of insect museum collections to map spittlebug distribution and host plants.
3. Genetic analysis to identify and differentiate spittlebug species.
4. Testing insects for bacterial communities, including known pathogens.
5. Feeding experiments to assess whether native insects could survive and reproduce on key crops.

What was found

• Over 20,000 insect specimens were collected, but only two native spittlebug species showed any potential to be Xylella vectors.
• Bathyllus albicinctus is widespread across Australia, feeds on a wide variety of plants (including grapevine, citrus, and olive), and was the most concerning species identified.
• Feeding tests confirmed that B. albicinctus can feed and reproduce on grapevines, citrus, and olives. Feeding patterns match those seen in overseas spittlebugs that transmit Xylella.
• No Xylella or similar pathogens were detected in field-collected insects. However, the diagnostic tools used were validated for use in insect testing, increasing preparedness for future surveillance.
• Genetic data and high-resolution imagery were developed to support rapid and accurate identification of native spittlebugs.

Industry relevance

This research has major implications for Australia's preparedness against Xylella fastidiosa, a top-priority exotic plant pest. If this pathogen were to enter the country, the native spittlebug Bathyllus albicinctus could potentially spread it within crops like grapevines, olives, and citrus.

What this means for growers

• Vigilance is critical – spittlebugs are present in vineyards and orchards across south-eastern Australia.
• Surveillance efforts should be timed for late spring to early summer, when spittlebug activity peaks.
• Sweep nets and light traps are effective tools for monitoring.
• Understanding local insect populations now helps ensure a faster, more effective response in the event of a future incursion.

This project has provided new tools and insights to help the winegrape and broader horticulture industries stay ahead of Xylella, protecting productivity, exports, and plant health into the future.