Professor YongLin Ren
PHOTO: Nicole Baxter
One of the most abundant minerals on the planet, silica (silicon dioxide), may hold the key to new products for controlling stored-grain insect pests. In laboratory trials led by Professor YongLin Ren at Murdoch University, a highly refined form of silica has achieved 100 per cent control of the four major stored-grain pests – lesser grain borer, rusty grain beetle, rust-red flour beetle and grain weevil – within five to 10 days.
And control was achieved at a product rate of 250 grams per tonne. This is about a quarter of the rate normally used for other silica materials, such as those derived from diatomaceous earth products, which are used principally as a structural treatment but also in grain to kill pests.
Professor Ren’s research has been funded by the GRDC through the Plant Biosecurity Cooperative Research Centre (PBCRC). PBCRC grains program leader Dr David Eagling reported on the progress of the new silica product research and development during the Australian Grain Storage and Protection Conference in June.
While phosphine is the industry standard for grain protection, the threat posed by insect resistance to the fumigant has renewed research into alternative strategies. Dr Eagling said this includes investigating non-chemical options such as aeration, nitrogen and silica-based products.
The new silica material being researched by Professor Ren is a highly purified form and the potential to control key stored-grain pests is the subject of international patenting by the PBCRC, Dr Eagling told the conference.
While the product has shown excellent potential for insect control, Dr Eagling said it was found to alter the grain specification of test weight, an important predictor of flour extraction rates for wheat. However, he added that a recent breakthrough has improved the efficacy of the silica product, which may resolve this issue.
These results, along with data on various product specifications, are being collated as part of an application to the Australian Pesticides and Veterinary Medicines Authority as the research team seeks a research permit to extend product testing into the field.
Dr Eagling said the PBCRC was now also considering the challenge of product distribution and application. He said it was likely that it would come with its own applicator to enable it to be admixed into grain streams.
Dr Eagling noted that it was unlikely to be economically viable to remove the product from grain once it had been applied. Along with regulatory approval, further work would be needed to assess the effects and acceptability of the product to Australian grain markets and end users.
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