The influence of bait presentation on bait uptake by mice (Mus domesticus) in infested urban domestic dwellings

Several researchers have established a link between the presence of house mouse (Mus domesticus) infestations and detrimental effects on human health. Controlling mouse infestations therefore requires methods that are quick, safe and effective. A tamper-resistant bait station with a wax block which is manufactured to fit within it so that it cannot be shaken out is considered the safest way to present the bait. However, some authors have expressed concern about the efficacy of this method. Research to examine the effects of bait stations on the feeding of mice infesting domestic dwellings was undertaken in the city of Manchester, UK. Working in conjunction with Manchester City Council, suitable sites were found. A balanced Latin Square experimental design was employed to overcome any operational biases that could have occurred. Non-toxic baits were presented in one of four ways: whole wheat in a cardboard box; whole wheat in a open tray; whole wheat in a tamper-resistant box; and a non-toxic wax block in a tamper-resistant box. Baits were placed in four different locations within dwellings and during the feeding trial; the bait stations were rotated, so that each bait type was presented in each location. The bait take from 12 dwellings within 3 housing blocks was recorded. Three-quarters of the bait consumed during the trial was taken from the cardboard box. No bait was taken from the tamper-resistant box containing the wax block. Risk assessments should drive the approach adopted in presenting rodenticide. Dwellings where vulnerable adults/children/pets are present may represent a risk of accidental poisoning may require a regime with tamper-resistant bait boxes containing wax blocks, to prevent baits being accessed. However, a balance between the safest and the most effective presentation of bait is needed and in areas where there is unlikely to be any access to baits (e.g. behind kitchen kickboards), use of alternatives must remain to ensure the shift resolution of infestations. Where bait can be placed safely and there are no children or pets present, cardboard boxes provide an effective means of ensuring that bait is consumed by the mice infesting domestic dwellings.