[Circadian rhythm of the dropping of engorged larvae in 2 species of ixodid ticks (Ixodidae) and its photoperiodic entrainment].

Daily rhythm of detachment of engorged larvae of Ixodes ricinus L. and Hyalomma anatolicum Koch is regulated by photoperiod. In photoperiodic conditions (16--20 hours of light p. d.) the maximum of detachment in H. anatolicum occurs at the beginning of photophase (the first 4--8 hours), but in I. ricinus it occurs at the second part of photo-phase (12--16 hours after the light is on). The rhythm of detachment is regulated according to the processes of endogenous circadian nature which are maintained in the continuous light and are species-specific. The phase entrainment of detachment in continuous light is also influenced by biorhythms of hosts.