In the battle against crop-damaging pests, Australian farmers have long relied on poisons and pesticides to keep mice at bay. Yet, these methods come with significant drawbacks, such as high costs and the unintended harm to other wildlife. Enter scent camouflage: an innovative strategy that promises to protect wheat crops by making them virtually undetectable to the olfactory senses of mice.
Mice, particularly the non-native house mouse (Mus musculus), are a formidable foe for Australian wheat farmers. During population surges, these rodents can wreak havoc, causing substantial losses to the country’s $13 billion wheat industry. Mice depend heavily on their sense of smell to locate food, specifically targeting wheat germ—the embryo inside the seed that develops into the plant. When populations spike, their relentless foraging can lead to devastating crop damage.
Peter Banks, a biologist at the University of Sydney, and his team sought a sustainable solution by drawing inspiration from a successful wildlife protection strategy used in New Zealand. There, scientists effectively threw nonnative predators off the scent of endangered birds by spreading bird scents in places birds would never be, like piles of rocks. The predators eventually dismissed these scents as misinformation, reducing predation on the actual birds when they arrived for nesting.
Adapting this concept to crop protection, Banks and his colleagues designed an experiment on a wheat farm in New South Wales, Australia. They divided the farm into 60 plots, each 10 by 10 meters, and applied wheat germ oil—a byproduct of wheat milling—to various plots in different manners. Some plots were sprayed with wheat germ oil before sowing, others after, and some were left untreated as controls. The idea was that overwhelming the mice with the scent of wheat germ would confuse them enough to prevent effective foraging.
The results were promising. Unlike the New Zealand study, where the approach didn’t work as expected, the scent camouflage in wheat fields showed remarkable success. In plots where the wheat germ scent was overwhelming, mice struggled to locate the seeds, leading to a significant reduction in crop damage. The camouflaged plots experienced 74% less damage compared to untreated plots, a finding that was published in Nature Sustainability (Volume 6 | September 2023 | 1041–1044).
Banks points out that the necessary equipment to spray wheat germ oil is already part of standard farm machinery, and the oil itself is an inexpensive byproduct, making this approach feasible for widespread adoption. However, as Peter Brown from the Commonwealth Scientific and Industrial Research Organisation cautions, there are still questions to address. Determining the optimal amount of wheat germ oil and the frequency of application remains critical before this method can be fully integrated into regular farming practices. Should it be used annually or only during mouse population peaks? These are questions that future research must resolve.
As farmers look for sustainable, cost-effective ways to protect their crops, scent camouflage offers a beacon of hope. This innovative approach not only promises to safeguard valuable wheat harvests but also aligns with broader ecological goals by reducing reliance on harmful chemicals.
