[Determination of the physiological age of alive Ixodidae ticks]

A method has been developed for lifetime determination of the physiological age of hungry imagoes on Ixodes and Dermacentor ticks of natural populations. The procedure has been used to study an alive tick in the liquid (water, physiological saline) against the light background. In doing so, some previously described anatomic and age-specific signs of Ixodes are imaged outwards and their overall age-specific signs are employed. The author has proposed the following criteria for determination of the age of ticks: appearance: 1) the body's thickness; 2) the wrinkles and colour of the cuticle, and the combined sign; 3) transcuticular visibility of the viscera. The last sign was earlier found [8, 9], which is basic in the new method. There is a significant generic specificity of its manifestation. Tables have been constructed for determining four main physiological ages (I-IV) of ticks of both genera. The method has been applied to the study of natural populations of I. persulcatus, D. reticulatus and D. marginatus in combination with virological studies. The method developed allows one to proceed to make a mass determination of the physiological age of alive ticks and basically expands the potentialities of its application.