Sorghum is one of the most important cereal grain crops on the Darling Downs and other grain growing regions of Australia. Sorghum crops on the Downs incur serious damage caused by mice because mouse numbers usually peaked from April to July when sorghum is bearing maturing grain. A manipulative experiment was conducted to parameterize a model of DT for managing yield loss (YL) due to damage to sorghum caused by mice (Mus domesticus L.) during crop maturation. DT was determined through estimating the relationship between YL and density of mice introduced to sorghum crops at the hard dough stage (DI). This relationship subsumed the functional and numerical response of mice to crops from the hard dough stage to harvest. The experimental crops were enclosed by mouse proofed pens. The experiment was conducted under conditions typical of sorghum fields to emulate natural habitat conditions for mice and crops. The estimated relationship was asymptotic exponential: YL increased almost linearly with DI until apparent competition between mice occurred at densities ≥ ~500 mice ha-1; and apparent competition limited further increases in YL at densities ≥ ~3,000 mice ha1. DT varies depending on the effectiveness of the control method in reducing DI and the cost of control as a percentage of the farm-gate value of sorghum. For example, DT was 178 mice ha-1 for triggering aerial zinc phosphide baiting if this method was effective in reducing DI by 52.58% and given the cost of baiting was 13.76% of farm-gate value of sorghum
