Artificial scent helps sniffer dogs detect biosecurity threat

Charles Darwin University (CDU) chemists have developed a scent profile and artificial scent lures to help sniffer dogs detect citrus canker disease in citrus orchards in the Northern Territory.

The Northern Territory’s citrus industry came under attack in 2018 from a highly contagious bacterial disease called citrus canker — which attacks lemon, lime, grapefruit, mandarins and native citrus plants, causing the fruit to drop to the ground before it ripens. Crops are destroyed, income drops and jobs are lost.

With the disease finally eradicated from the Territory three years later, CDU chemists Dr Hao Wang and Dr Vinuthaa Murthy won a contract with the Department of Industry, Tourism and Trade to synthesise artificial scent lures specifically for the detection of citrus canker, should the disease return.

Dr Murthy said the project set out to determine the volatile organic compound profile of the infected citrus plants at CDU’s Yellow 2 labs using a gas chromatography mass spectrometer.

“We analysed and identified key chemical compounds that were emitted by different citrus varieties in both infected and non-infected plants,” she said. “We were then able to develop the chemical composition of the scent blend to make an artificial lure which is used to train detector dogs.”

Detector dogs can discover the disease before symptoms are visible to the human eye. The dogs can also search large farms and orchards very quickly, compared with previous methods. Two sniffer dogs are now trained to detect citrus canker in infected plants using the artificial lure.

“It was a challenging and exciting project to be involved in, and extremely satisfying, because not only does our work help protect the citrus industry, it has the potential to detect all kinds of biosecurity threats,” Dr Murthy said.

Image caption: Dr Vinuthaa Murthy and Dr Hao Wang developed a scent profile to detect citrus canker disease.

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