Seasonal activity of the common European tick, Ixodes ricinus (Linnaeus, 1758), in the forested areas of the city of Olsztyn and its surroundings.

UNLABELLED Common European ticks, Ixodes ricinus, have been found in forest areas situated within the boundaries of big cities, and in areas changed by anthropogenic pressure. Monitoring I. ricinus, in the areas used by the public for recreation and leisure, makes it possible to assess the risk of infection with the diseases they transmit. The objective of this study was the comparison of the seasonal activity of ticks, I. ricinus, in the afforested areas of the city of Olsztyn and its surroundings. MATERIAL AND METHODS This survey was conducted at sites located in the afforested areas of Olsztyn and within the Warmiński Forest situated about 15 km from Olsztyn. Ticks, I. ricinus, were caught every 10-14 days from April to October 2001 by the commonly applied method of flagging. During each catch, the temperature (T) and relative humidity (%RH) was measured with a thermohygrometer, 1 m above the duff level. RESULTS The tick population density at the Warmiński Forest site was higher than that at the sites within the city limits (116.8 and 20.5 ticks per 100 m2, respectively). Two peaks of tick activity were recorded in this area--the spring peak in June and the autumn peak (much lower) in September. The activity of ticks in the afforested area within the city limits was much lower--only one (spring) peak occurred, which at most sites was observed in June. At all sites, included in the study, the peak activity of ticks was observed in April. CONCLUSION The study suggests that the afforested areas outside the city are more dangerous to people than the area within the city because of the large number of ticks there.