Early warning signs another mouse plague is on the way
As mouse populations explode in some of Australia’s key growing areas, scientists are seeing early warning signs that another epidemic is on the way.
CSIRO research officer Steve Henry said parts of South Australia experienced 20 months of dry weather followed by 200mm of in-crop rainfall, and these conditions were known to trigger the plague.
There has been an increase in catches in rat monitoring areas across South Australia’s Adelaide Plains, Yorke Peninsula and Eyre Peninsula, as well as Victoria’s Wimmera region.
Mr Henry said trap rates were as high as 30 per cent in some of these areas, compared to 10 per cent in a normal season.
“All the females we caught were showing signs of breeding,” he told AAP on Tuesday.
“So they were either pregnant or had recently had a baby.”
Although monitoring continues, there was less concern about mouse numbers in cropping areas in central western NSW and the Darling Downs in Queensland.
Mr Henry said with the harvest well underway the mice were unlikely to cause serious damage until next season.
Farmers have been urged to harvest as cleanly as possible to limit the rodents’ food supply, then watch out for increasing numbers of mice in the stubble.
“By doing this, they will have a good understanding of how many mice are in their stubble and will be ready to take action by baiting before planting next year’s crop,” Mr Henry said.
He said the agriculture industry is better prepared for another disaster following the rat epidemic that caused an estimated $1 billion worth of damage in many states in 2021.
Subsequent laboratory tests and field trials helped scientists better understand how the toxin zinc phosphide worked to destroy mice.
A single rodent would have to eat two or three poison-laced grains to receive the lethal dose.
“What we need to do in the paddocks is create an environment that gives them the best chance of exploring those two or three grains,” Mr Henry said.
“The key is to reduce the amount of other food around so the mice are not distracted by the other food.”
Mr Henry said research after the 2021 disaster estimated the cost of damage to rural NSW alone at $660 million; This figure was a figure that signaled the need for action to prepare against another epidemic.
“This is a huge figure in rural communities and much of the cost of dealing with rats is borne by farmers,” Mr Henry said.
“In rural communities there are all the costs of losing stock in supermarkets, plus the problems of going after rats because rats can get anywhere.
“It’s much better measured now that we’ve done this work.”
