A method developed by researchers at the University of Sydney has the potential to revolutionize the way crop losses caused by mouse plague are tackled. NSW Farmers has estimated that the scourge of mice could cause $1 billion in damage to Australian crops by 2021.
The research was led by PhD student Finn Parker with co-authors Professor Peter Banks, Dr. Catherine Price and Jenna Bytheway from the Sydney Institute of Agriculture and the School of Life and Environmental Sciences.
The team estimated that mice successfully steal 63 percent fewer wheat seeds compared to untreated controls if the wheat crop is sprayed with diluted wheat germ oil during and after sowing.
The researchers found that if the wheat plot was also sprayed with the same solution before planting, then seed loss was reduced by an even better 74 percent. They said this was because the mice had learned to ignore the ungrateful smell of wheat by the time the crop was planted.
“We found that we can reduce mouse damage even during plague conditions simply by making it harder for mice to find food and by masking the smell of the seeds.” Because they’re hungry, they can’t spend all their time looking for food, which is hard to find,” Professor Banks said.
“When the scent of the seed is everywhere, they’ll just go look for something else instead of encouraging them to dig. That’s because mice are precise foragers that feel seeds in the ground and dig exactly where the seed is, but they can’t do that in this situation because everything smells like seeds.”
“This misinformation tactic could work well in other crop systems, indeed any animal that finds food by smell is potentially vulnerable to us manipulating that smell and undermining its ability to search.”
Mr Parker said masking could be an effective solution for wheat growers, given wheat’s short vulnerability. “It appears that the camouflage lasted until the seeds germinated, which is a vulnerable period when wheat needs to be protected,” he said.
“Most of the damage to mice occurs from seeding to germination, less than two weeks later, Mice cannot develop resistance to this method because it uses the same smell that mice rely on to find wheat seeds.”
The research was conducted in May 2021 on a farm 10 km northwest of Pleasant Hills, New South Wales, where five treatments were tested in 60 plots.
Two of the treatments involved a solution of wheat germ oil. The other three treatments were controls, with plots covered with canola oil, trampled or untreated. All control treatments performed similarly and suffered significantly more damage than treated plots.
Wheat germ oil is a relatively inexpensive by-product of the milling process. The authors said their solution, which contains only wheat germ oil diluted in water, offers a sustainable, non-lethal alternative to pesticides and baits.
“If people want to control mice but can’t get numbers low enough, our technique can be an effective alternative to pesticides or add value to existing methods,” Dr Price said.