Abstract:
A large fraction of the forests in northern Belgium consists of homogeneous pine stands on nutrient-poor
and acid sandy soils. However, in common with many other parts of Europe, the current forest management
aims at increasing the share of deciduous and mixed forests. This might create favourable habitats
for the tick Ixodes ricinus, which is Europe’s main vector of Borrelia burgdorferi sensu lato, the causative
agent of Lyme borreliosis in humans. Considering the threat to human health, it is important to know
which factors regulate tick abundance. The influence of local habitat and landscape variables on the
abundance of I. ricinus ticks were studied by collecting questing larvae, nymphs, and adults at 176 locations
in forests in the Campine region (northern Belgium). Both I. ricinus ticks and B. burgdorferi spirochetes
occurred throughout the study area, which means that the entire region represents an area of
risk for contracting Lyme borreliosis. At the forest stand level, the main tree species and the shrub cover
significantly affected the abundance of all life stages of I. ricinus. The abundance was higher in oak stands
compared to pine stands, and increased with increasing shrub cover. Additionally, at the landscape level,
a positive effect was found for forest edge length but not for forest cover. These patterns may be
explained by the habitat preferences of the tick’s main hosts. Our results indicate that forest conversion
might indeed create suitable habitats for ticks, which highlights the need for intensive information campaigns
and effective tick control measures.
