University of Adelaide researchers have developed a novel chemical-free and resistance-free way of protecting stored grain, such as this buckwheat, from insects.Photo credit: Mariluna, Wikimedia CommonsThe researchers are taking advantage of the unique properties of these single-celled algae, called diatoms. Diatoms have been called Nature's nanofabrication factories because of their production of tiny (nanoscale) structures made from silica which have a range of properties of potential interest for nanotechnology.

"One area of our research is focussed on transforming this cheap diatom silica, readily available as a by-product of mining, into valuable nanomaterials for diverse applications - one of which is pest control," says Professor Dusan Losic, ARC Future Fellow in the University's School of Chemical Engineering.

Their research is being presented at this week's ICONN2014-ACMM23 conference for nanoscience and microscopy being hosted by the University of Adelaide at the Adelaide Convention Centre.

"There are two looming issues for the world-wide protection against insect pests of stored grain: firstly, the development of resistance by many species to conventional pest controls - insecticides and the fumigant phosphine - and, secondly, the increasing consumer demand for residue-free grain products and food," Professor Losic says.

"In the case of Australia, we export grain worth about $8 billion each year - about 25 million tonnes - which could be under serious threat. We urgently need to find alternative methods for stored grain protection which are ecologically sound and resistance-free."

The researchers are using a natural, non-toxic silica material based on the 'diatomaceous earths' formed by the fossilisation of diatoms. The material disrupts the insect's protective cuticle, causing the insect to dehydrate.

"This is a natural and non-toxic material with a significant advantage being that, as only a physical mode of action is involved, the insects won't develop resistance," says Professor Losic.

"Equally important is that it is environmentally stable with high insecticidal activity for a long period of time. Therefore, stored products can be protected for longer periods of time without the need for frequent re-application."

PhD student Sheena Chen is presenting her findings on the insecticidal activity of the material. PhD student John Hayles is also working on the project. The research is funded by the Grains Research and Development Corporation. The researchers are in the final stages of optimising the formula of the material.