Cattle in nature reserves reduce the nuisance caused by ticks and also lower the risk of Lyme's disease. This is because the cattle change the vegetation, and thereby the habitats of the wood mouse and the bank vole. As a result, these important hosts of ticks have fewer opportunities and the population of ticks declines. This was one of the findings of a study conducted by Wageningen University into the effects of cattle in forests on tick populations and Borrelia bacteria in ticks, which cause Lyme's disease. The study was published in Applied and Environmental Microbiology.
In one part of their study, the researchers compared a grazed area within an ungrazed area. The study showed that the tick population was significantly higher in the wooded area where cattle were present than in the forest where no cattle were present. In the ungrazed areas, the tick population was higher in the forest dominated by oak trees than in the forest dominated by pine trees. This difference was not found in the grazed area. The cattle in the forest did not have any effect on the Borrelia Infection rate in ticks. However, the forest type did have an effect on the Borrelia infections; in the oak forest, the infection percentage in ticks was higher than in the pine forest. On average, 26% of young ticks were infected and 33% of the adult ticks.
There is currently a great deal of interest about research concerning ticks and Lyme's disease. In recent years, the number of cases of Lyme's disease in the Netherlands and Germany has increased sharply. The researchers suspect that this is caused by the combination of expanding nature reserves, the growth in deer populations and mild winters. These conditions are beneficial for ticks. They also suspect that the increased incidence of Lyme's disease is caused by more outdoor recreation. This increases the probability of people coming into contact with ticks.
Note to the editor
For more information, please contact Fedor Gassner, MSc, Laboratory of Entomology, Wageningen University, tel. 0317 484 657, e-mail Fedor.gassner@wur.nl, or Bouke de Vos, Wageningen UR press and science information officer, tel. 0317 480 180, e-mail bouke.devos@wur.nl.