Thermal Constants of Development of Ixodes persulcatus and Ixodes ricinus Ticks, Which Determine the Duration of Their Life Cycle and Their Distribution

A critical analysis of the concept of a “thermal constant of development” in acarology is presented. Thermal constants were calculated based on the range of environmental conditions in the optimal distribution areas. The obtained constants of egg development and metamorphosis of larvae and nymphs are given for the taiga tick Ixodes persulcatus Sch., 1930 and the European forest tick I. ricinus L., 1758. The significance of these parameters for analyzing the distribution patterns and ecology of these tick species is discussed.