Managing crop damage caused by house mice (Mus domesticus) in Australia

A large-scale outbreak of the house mouse populations occurs in grain growing in Australia on average once every four years. High densities of mice cause major yield losses to cereal crops, and low to moderate densities of mice also cause some losses. Several predictive models based on rainfall patterns have been developed to forecast mouse density. These models carry some uncertainty and the economic value of basing management actions on these models is not clear. Baiting is the most commonly used method and zinc phosphide and other rodenticide bait are effective in reducing up to 90% of mouse populations. Ecologically-based best farming practice for controlling mice has recently been developed on the basis of long-term field studies of mouse populations. No effective biological control method has been developed for mice. However, grain growers still cannot make economically rational decisions to implement control because they do not know the pest threshold density (D(T)) above which the economic benefits of control exceed the economic costs of control. Applied predator-prey theory suggests that understanding the relationship between mouse density and damage is the basis for determining D(T). Understanding this relationship is the first research priority for managing mouse damage. The other research priority is to develop a reliable method to estimate unbiased mouse density.