To stop mice from eating seeds … make everything smell like seeds?

By digging up and eating sown wheat seeds, mice can have a huge impact on farmers’ crops. In an eco-friendly effort to stop the rodents from doing so, scientists are now using wheat germ oil to make entire fields smell appetizing.

Ordinarily, mice sniff out individual wheat seeds either before or during the germination process. Once that process is complete and the plants have sprouted, the creatures largely lose interest.

Many people might think that in order to keep mice away from the seeds, those seeds should be made less appealing to the animals. However, not only would doing so involve having to chemically treat all the seeds, but the mice might also develop a tolerance for the chemicals over time.

Instead, a University of Sydney team led by PhD student Finn Parker took a more-or-less opposite “camouflaging” approach.

By spraying entire wheat plots with wheat germ oil diluted in water, the researchers made all of the soil, stubble and everything else smell like germinating wheat seeds. Because mice therefore couldn’t determine where the actual seeds were planted, they found and ate far fewer of them.

The scientists conducted the trials in May 2021, on 60 wheat plots located on a farm in the state of New South Wales. Some of the plots received the wheat germ oil treatment, while others were sprayed with canola oil, trampled, or left untreated as controls.

It was found that as compared to the untreated controls, 63% fewer wheat seeds were eaten by mice in plots that had been sprayed with wheat germ oil during and after sowing. If the plots had been sprayed prior to sowing, the figure increased to 74%. The canola-oil-treated and trampled plots didn’t fare much better than the controls.

“The camouflage appeared to last until after the seeds germinated, which is the period of vulnerability when wheat needs to be protected,” said Parker. “Mice can’t evolve resistance to the method either because it uses the same odor that mice rely on to find wheat seeds.”

The scientists are now investigating which concentrations of wheat germ oil work best, and how often the solution needs to be applied to crops in order to stay effective.

A paper on the study – which was co-authored by Prof. Peter Banks, Dr. Catherine Price and research assistant Jenna Bytheway – was recently published in the journal Nature Sustainability.

Source: University of Sydney

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