DIEL ACTIVITY OF IXODES-RICINUS ACARI, IXODIDAE AT 2 LOCATIONS NEAR STOCKHOLM, SWEDEN

The diel 'activity', i.e. availability, of Ixodes ricinus larvae, nymp hs and adults was investigated in a meadow and a forest habitat near S tockholm during 1991-1993. Generally, the immature ticks were more pre valent in the forest than in the meadow. In the meadow, the mean larva l and adult numbers varied significantly between 4 h time intervals wi th the peak activity from 2300 to 0300 h. In the forest, the tick numb ers did not differ significantly between the time intervals. The assoc iation of the tick activity with certain meteorological variables was strongest in the meadow, where the mean numbers of all tick stages wer e negatively correlated with the temperature. The relative humidity wa s positively correlated only with the mean numbers of larvae. In contr ast, the larval activity in the forest was positively and negatively c orrelated with the temperature and relative humidity, respectively, wh ile the nymphal and adult activity showed no association with these cl imatic variables. The impact of the host activity on the tick diel act ivity is also discussed.