[The abundance and distribution of the Ixodes persulcatus (Acari: Ixodidae) near its northern spreading limit in the Ural Mountains].

A count of the tick species Ixodes persulcatus Schulze, 1930 was carried out in the "Denezhkin Kamen" Nature Reserve and adjacent territories (the Severoural'sk and Ivdel' Districts of the Sverdlovsk Region, the Northern Urals geographical province) in the 2005. The abundance and distribution of unengorged adults has been evaluated on an area of 22.5 square kilometers (N 60 degrees 27'-60 degrees 30' E 059 degrees 38'-059 degrees 42'). The area includes proportionally main landscape and vegetation elements of the region studied, from mountain analogues of the middle and northern taiga up to tundra. One tick species, I. persulcatus, has been collected by flagging with the abundance from 0.4 up to 6.8 (average 1.6 +/- 0.9) specimens per flag-hour. The observed values of abundance are classified into three classes (I - ticks are absent, II - 1-2 specimens, and III - 3-7 specimens per flag-hour). The class I amounts 20, II - 75, and III - 5% of the area examined. It has been revealed by the expert evaluation of the 2003-2004 and counts of the 2005 that ticks occur stably in the Northern Ural, reaching N 61 degrees and 400 m above sea level. The level of the species abundance remained constant till the middle of summer. In this period the activity of ticks dependent on the weather optimum only.