The tiny discovery with big biosecurity benefits

The tiny discovery with big biosecurity benefits

12 July, 2017

  • A new bacterium has been discovered inside an Australian native psyllid, a tiny sap-sucking insect

  • The bacterium is a new candidate species of Liberibacter and is named Candidatus Liberibacter brunswickensis (CLbr)

  • The bacterium is not associated with any plant disease, unlike closely related exotic species that cause destructive zebra chip disease and citrus greening

  • The discovery will help reduce false positive results in testing, which can have a significant impact on trade

Plant Biosecurity CRC researchers based at Agriculture Victoria's AgriBio, Centre for AgriBiosciences, have discovered a new bacterium, a novel candidate species of Liberibacter, inside a native Australian eggplant psyllid, Acizzia solanicola. Its discovery can help ensure diagnostic tests do not give false results for destructive diseases associated with other types of psyllids. The benefits for industry are potentially significant, as false results can be highly damaging for trade.

Psyllids are tiny insects that can spread bacteria that cause devastating plant diseases, such as zebra chip disease in potatoes and citrus greening – diseases that are not yet present in Australia.

“The new species has not been associated with any plant disease but its discovery can help ensure we don’t get false test results which can be devastating for trade,” said project leader Dr Brendan Rodoni, Principal Research Scientist with Agriculture Victoria.

The tomato potato psyllid (TPP), Bactericera cockerelli, is known to spread zebra chip disease and has recently been detected in Western Australia. TPP and the eggplant psyllid both feed on eggplants, making this research very relevant to the large scale surveillance for TPP currently taking place across Australia.

Plant Biosecurity CRC PhD candidate Jacqueline Morris is profiling the bacteria present in the eggplant psyllid. Understanding the gut bacteria, or microflora, of the eggplant psyllid supports the development of diagnostic tools that can help quarantine and other end-users to detect and diagnose new and existing bacterial plant pests more accurately and efficiently.

Both zebra chip and citrus greening diseases pose severe threats to Australia’s potato and citrus industries. The spread of zebra chip disease following an incursion in New Zealand cost potato growers an estimated $NZD 200 million (2006-2012), while citrus greening disease is fatal to citrus and cost Florida $USD 3.63 billion (2006-2012) in lost revenues and 6,611 jobs.

“Diagnostic tests are available for these diseases but they have been developed outside Australia,” said Dr Rodoni. “It’s possible for native, non-disease causing Australian bacteria to generate a false result, which could be catastrophic to trade.”

The discovery is an exciting find for Jacqueline’s CRC supported PhD project; the paper Novel ‘Candidatus Liberibacter’ species identified in the Australian eggplant psyllid, Acizzia solanicola has recently been published in Microbial Biotechnology.


Contact: Tony Steeper, Plant Biosecurity CRC Communications, t.steeper@pbcrc.com.au, 02 6201 2882, 0417 697 470

More information: Psyllid microflora - Implications for Liberibacter disease surveillance and pest control

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