Citrus industry biosecurity and incursion management, following CT07026 (CT10025)

This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

Project CT11002 furthered the significant progress achieved in CT07045 towards achieving the suppression of Fuller’s Rose Weevil (FRW) required for market access to China and other east Asian countries with similarly stringent quarantine protocols. Field research findings were used to “fine tune” the integrated Best-Practice management program and scouting protocols. This assured that the Best-Practice Program was effective and remained so for a number of seasons. This encouraged the already widespread uptake of the FRW program, thereby providing more growers with the option of expanding their export markets and improving the industry’s security of fruit supply for export to FRW-sensitive markets.

Understanding of the biology of Island fly (Dirioxa pornia) was improved in CT07045, however, breakthrough in project CT11002 allowing their successful laboratory culturing led to the development of a Degree Day model and improved understanding of the relationship between Island fly and their symbiotic bacteria. This relationship between fruit fly and the bacteria provided opportunities to improve the Sterile Release Technique for pest fruit flies such as Ceratitis capitata and Bactrocera tryoni. The bacteria also provided opportunities to develop improved lures for monitoring programs and lure and kill management of fruit flies.

The key findings were: 

• Updated Best-Practice guide for FRW.
• Establishment of rearing method for Island fly.
• Confirmation that citrus is a conditional non-host of Island fly.
• Island fly populations were correlated with fruit on the orchard floor.
• Island fly constant temperature development model.
• Bacteria isolated from the gut of Island fly have potential for development as a lure and some species may be pathogenic to other Tephritid fruit fly species.

While initial research conducted as part of CT07045 and CT11002 provided an effective field management protocol for FRW, future R&D was required to evaluate other chemical options in the field to ensure ongoing success of the export programme. The area that needed most research and development in the future was post-harvest disinfestation and further development of vital stain technologies available to increase the efficiency and verification of fumigation and other post harvest technologies.

Further R&D was required for Island fly, particularly with regards to possible use of bacteria as a control option which may also transfer to other species of Tephritid fruit fly such as C. capitata and B. tryoni. The highly attractive nature of some of the identified bacteria were reccomended to be further investigated for development of attractants for Tephritid species for which Hort had no or only poorly performing lures.