On the scent of grain insects

Photo of a young man in a white coat

Postgraduate PhD researcher Yonghao Nui operates
a gas chromatograph to evaluate volatile chemicals in
insect-infested grain at Murdoch University, WA.

Understanding the biological and chemical make-up of insect signals could lead to the development of a new diagnostic tool for detecting pest-infected grain.

Postgraduate PhD researcher Yonghao Nui has started research focusing on this issue at Murdoch University’s post-harvest plant biosecurity laboratory.

Initially, he is examining how the volatile chemicals from insects (Rhyzopertha dominica (F.) and Tribolium castaneum) can be used to identify their presence in grain.

Mr Nui’s supervisor, Dr Manjree Agarwal, says the detection and quantification of insects in stored grain and other agricultural products has proven a difficult task.

“Current detection approaches for grain are based on representative sampling of stacks, trucks and rail bogies, and manual inspection for adult insects,” Dr Agarwal says.

However, the industry consensus is that this approach is not sensitive enough, she says.

Scientific insect detection methods include measuring carbon dioxide, pheromones and the colour changes of samples, plus a wide variety of measures for trapping adult insects and sensing insect noise and volatile chemicals in odours.

To date, there is no effective method for in situ detection of insects in grain masses using electronic instrumentation without also grain sampling. Keeping these drawbacks in mind, the new method Mr Nui is developing uses head space solid phase microextraction (HS-SPME) and gas chromatograph mass spectrometry (GC-MS).

Applying these techniques, air within a grain mass can be analysed for the whole spectrum of volatile chemicals present in grain infested with insects.

“If the chemo-metric ‘signature’ peaks of the key stored grain insects, Rhyzopertha dominica and Tribolium castaneum, are identified through their volatile chemical signals, we can say that the grain is infested with these pests,” Dr Agarwal says.

More information:

Dr Manjree Agarwal,

08 9360 6403,


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