Life cycle of the taiga tick Ixodes persulcatus (Acari: Ixodidae) in the North-West of Russia.

The life cycle of Ixodes persulcatus lasts 3 years in the conditions of the Leningrad province (North-West Russia), the development of each phase taking a year. The normal age of the taiga tick is 3 years. The calendar age of larvae and nymphs reaches 11-12 months under favorable abiotic and biotic factors, while the calendar age of adults does not exceed 11 months. At the preimaginal phases of development the ticks that breed in August can feed before or after winter. However, their metamorphosis begins and reaches completion within the same timeframes (from late June to early August) and lasts for about 30-50 (60) days. The survival rate of hungry and engorged larvae and nymphs after wintering is quite high (88.6-100 %). We explain the low activity of larvae and nymphs in late summer and autumn by incomplete development. Morphogenetic diapause of engorged larvae and nymphs interrupts digestion but not metamorphosis which starts only in late June and July after the complete absorption of blood from the gut cavity.