Monitoring of two tick species (Ixodes persulcatus Schulze 1930 and Ixodes pavlovskyi Pomerantsev) was performed in four city parks of Tomsk, Russia (Camp Garden, University Park, Southern Cemetery, and Polytechnic Stadium) and in a control wild biotope in city environs (Kolarovo) in 2002-2013. Ticks were collected by flagging repeatedly after each 10 ± 1 days, starting from the disappearance of the snow cover till the end of tick activity (April-August). Gradual penetration of both tick species into city parks was demonstrated. In the wild biotope, I. persulcatus dominated during the whole period of monitoring, forming about 95% of tick population, whereas in urban biotopes I. pavlovskyi became the dominant species. Two peaks of population density during each season of spring-summer activity were observed in both species. Possible explanations of the phenomena are discussed.
Amputation of legs in nymphs of ticks, obtained from the first laboratory generation, resulted in regeneration of the legs after moulting to adults. Haller's sensory organ on the upper surface of each foreleg tarsus was significantly modified following regeneration. Haller's organ in non-amputated legs of the experimental ticks remained unchanged, being comparable to controls. Pored olfactory sensilla in the anterior pit, in a capsule and on a distal knoll usually increased in number, as well as grooved, thin and conical sensilla. Bordering gustatory and double-walled postcapsular sensilla either decreased or increased in number. All additional sensilla were consistent in their location. Form of the anterior pit and capsule's aperture also deeply changed after the regeneration. The authors distinguish this changes as atavistic. No correlation between changes in different parts of the organ were found. A phenomenon of induction was discovered in our study: if a distal part of tick's gnathosoma was amputated together with the left foreleg, Haller's organ in the right, untreated leg possessed the same changes after moulting as the regenerated organ in the previously amputated left foreleg.
A study of Haller's organ regeneration in nymphs and adults of Haemaphysalis turturis and parthenogenetic females of H. longicornis, from which the forelegs had been amputated during the previous instar, revealed structural changes in regenerated organs. The adult regenerates reestablished atavistic structural features, while the nymphal regenerates retained larval features, which is typical of regenerates of two other genera examined previously (Ixodes and Hyalomma). Data on regeneration of Haller's sensory organ testify to an ancient character of the genus, standing closely to the base of the phylogenetic tree of hard ticks.
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