The stench of decay hangs over the New South Wales Riverina. It is not death of the usual kind. It is the smell of 10,000 mice per hectare, their bodies rotting in walls, in sheds, in the earth. This is not hyperbole. This is the lived reality of a rural community under siege by one of the most severe rodent plagues in Australian history. And now, British agricultural science has been deployed, bringing a tool designed for a different crisis but perhaps adaptable to this one: the genetic modification of the mouse itself.
To understand the scale, consider this. A single female mouse can produce 50 offspring per year. With a gestation of 19 days, the population doubles every five weeks. Exponential growth is not a theoretical concept. It is a mathematical certainty. In the Riverina, farmers are reporting losses of 100,000 Australian dollars per property. Grain silos are contaminated. Hay bales are hollowed out. Machinery is chewed through. The mice are everywhere, their urine and faeces rendering buildings uninhabitable. The smell, as one farmer described, is 'like a decaying body.'
This is not an isolated event. Mouse plagues are cyclical in Australia, triggered by ideal breeding conditions: a wet winter followed by a warm spring. But this year, the conditions were extraordinary. 2020 and 2021 saw La Niña-driven rains that broke a decade-long drought. The result was an explosion of vegetation, a feast for mice, and then the inevitable crash when the food ran out, sending the rodents into farmsteads and towns.
The British intervention comes from the University of Cambridge’s Department of Genetics. Their tool is not a poison, but a genetic edit. Using CRISPR, scientists have developed a method to create 'daughterless' mice. The idea is simple: alter a gene that is essential for female fertility. When such mice are released into the wild, their offspring will be born, but the females will be sterile. Over generations, the population collapses. This is not a new idea. It has been used for insects, but never for mammals on a continental scale.
The ethical questions are enormous. Genetic modification of a wild population is a form of terraforming. It is irreversible. The mouse, Mus musculus, is an invasive species in Australia, but it is also a native of Europe and Asia. Could such a gene spread to other populations? The scientists are cautious. The technology is contained within an RNA switch that activates only in the presence of a specific trigger, such as a chemical in bait. But in a country where mice have already evolved resistance to warfarin, a blood thinner, one must wonder if evolution will outpace engineering.
There is also the ecological dimension. Mice are prey for owls, snakes, and foxes. A sudden collapse of the mouse population would cause those predators to starve or turn to livestock. The biosphere is a web, and pulling on one strand can unravel the whole. Yet the alternative is a continued chemical war. Zinc phosphide baits are being dropped from planes. They kill mice, but also birds, reptiles, and pets. The body count is already high.
The Australian government has declared the plague a 'national emergency.' The New South Wales cabinet has released 50 million Australian dollars in disaster relief. But money cannot buy time. The mice are breeding as I write this. The clock is ticking. British science may offer a solution, but it is a solution born of our failure to manage ecosystems. We created the perfect conditions for this plague: monoculture crops, irrigation, and climate change. Now we are looking for a genetic silver bullet.
As a scientist, I am trained to be optimistic about technology. But I am also trained to see the data. The data says we are moving into an era of ecological instability. This mouse plague is a symptom of a larger syndrome: a world where the rules are changing. The British intervention is a stopgap, a tool for a crisis. But it is not a cure. The cure lies in how we farm, how we use water, how we live with the land. Until then, the smell of decay will remain.
