Resistance to rat poison is increasing: the search for sustainable and effective control methods
Brown rats feel very much at home in human surroundings, where they find plenty of food and shelter. Rat infestations can sometimes occur, but with good management, damage and nuisance can be kept to a minimum. Prevention and mechanical control are the first choice, but rodenticides are sometimes necessary. Traditional rodenticides, which affect blood clotting (anticoagulants), can be harmful to other animals and the environment. They also raise questions about animal welfare and are becoming less effective as rats develop resistance.
That is why the INBO has been conducting research into the control of brown rats and their increasing resistance to anticoagulants for some time. The most recent genetic screening in 2024 confirms the concern: half of the Flemish rat population is now resistant. This is a clear increase compared to 2013, when approximately one in five rats was resistant. The resistance is particularly visible in the east and west of Flanders, but is slowly spreading to the centre.
In order to tackle rat infestations in a sustainable manner, the INBO developed a monitoring tool for local authorities. This tool maps reports of infestations and control measures, thereby supporting effective and efficient management. In addition, cholecalciferol (vitamin D3) was tested as a promising alternative for resistant populations. A coordinated approach and carefully considered measures remain essential in this regard.
Michiel Lathouwers, Kristof Baert
Image: Rollin Verlinde - Vildaphoto