University of Adelaide researchers have been using nanotechnology and the fossils of single-celled algae to develop a novel chemical- and resistance-free way of protecting stored grain from insects.
The researchers are taking advantage of the unique properties of single-celled algae, known as diatoms. These have been called nature's nanofabrication factories because of their production of 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, which is readily available as a by-product of mining, into valuable nanomaterials for diverse applications. One of these is pest control," said Prof. Dusan Losic of the university's School of Chemical Engineering.
"There are two looming issues for the worldwide protection against insect pests of stored grain: first, 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," continued Losic.
"In the case of Australia, we export grain worth about A$8bn (US$7.2bn) each year—about 25m tonnes—which could be under serious threat. We urgently need to find alternative methods for stored grain protection that 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 an insect's protective cuticle, causing it 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," said 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 will reveal her findings on the insecticidal activity of the material, and fellow 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.