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Stored Grain Pests Probed in WA Research

03 May 2012

AUSTRALIA - Western Australian research investigating the ecology of major pests of stored grain is expected to result in improved management practices and minimise the development of resistance to fumigants.

The Department of Agriculture and Food (DAFWA) and bulk handler the CBH Group are collaborating in the research which will help ensure Australian cereal grain continues to meet market requirements, including nil tolerance to live insects in export grain.

The study is part of a bigger insect ecology project within the Cooperative Research Centre for National Plant Biosecurity (CRCNPB), of which the Grains Research and Development Corporation (GRDC) is a partner.

A grain insect ecology trap near a grain storage facility in WA.

Led by Greg Daglish of the Queensland Department of Agriculture, Fisheries and Forestry (QDAFF), it involves research in the GRDC’s northern, southern and western regions.

Gimme Walter from The University of Queensland is providing ecological expertise and access to population genetics skills and resources.

The insect ‘ecology’ being studied under the project refers to the broad biological issues associated with the pests – including emigration, immigration, reproduction rates, timing of flight and other issues.

The WA component of the project, which started in 2011, is studying the insect ecology of two beetle species - the lesser grain borer (LGB) (Rhyzopertha dominica) and the rust red flour beetle (RFB) (Tribolium castaneum).

Both these insects are impediments to market access and are capable of developing resistance to phosphine, commonly used for insect control.

In the study, the researchers are looking at ‘gene flow’, which refers to the way in which distinct strains of the insects (which could include phosphine-resistant strains) spread, and where they go.

DAFWA senior entomologist Rob Emery, who is leading the WA insect ecology project with Ern Kostas, of the CBH Group, said the WA study provided an opportunity to investigate gene flow on a large geographical scale.

Mr Emery said he hoped the results of the study would assist fumigation practices, including timing of applications.

“Information about insect movements and behaviour, generated through trapping work, could help us conduct better timed fumigation of stored grain and avoid unnecessary fumigations which increase the risk of resistance developing,” he said.

Mr Emery said traps baited with species-specific pheromone lures were being used to monitor flight activity at 12 sites at CBH storage facilities throughout the WA grainbelt.

He said it was important to investigate gene flow in the species to help determine how closely related different insect populations were, and therefore whether resistance was spreading between sites, or developing independently.

"Unlike the eastern states where phosphine resistance is more widespread, strong resistance has only been found in five WA locations in the last five years, including three sites closely located on farms near Beacon," Mr Emery said.

“So far it is unknown whether the three strongly resistant populations near Beacon have developed independently – due to similar management practices – or from movement of resistant insects between the farms."

“The insect ecology project will provide us with more information about how resistance develops and spreads.”

Mr Emery said the research would also reveal whether resistant populations of insects could spread from a farm to bushland, and then reinfest other farms.

“If the insects prove to be very mobile and capable of surviving in bushland and reinfesting grain on nearby properties, this threatens the WA grain industry’s ability to maintain a ‘clean pipeline’ of insect-free grain,” he said.

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