Determination of the parameters of the parasitic stage in Ixodes ricinus females

Introduction and objectives: Ixodes ricinus is a tick commonly found on human and animals and of great medical and veterinary importance. The aim of the study was to determine the parameters of different stages of feeding in Ixodes ricinus females. Methods: 229 Ixodes ricinus females were collected from 102 animals – roe deer (Capreolus capreolus) and red deer (Cervus elaphus) culled in southern and south-eastern Poland in 2002. Each female was weighed and the length and width of the scutum as well as the width of the idiosoma were measured. 20 tick females were collected from vegetation growing in the region and analysed in order to compare the changes in the parameters studied to those exhibited by unengorged specimens. Results: Three groups were identified on the basis of female body weight; group I consisted of 52 females in feeding phase I with body weight in the range of 0.0003–0.0043 g (mean 0.0019 g), group II comprised 150 females in feeding phase II with weight in the range of 0.0017–0.3075 g (mean 0.0263 g), and group III consisted of 27 females in feeding phase III with weight in the range of 0.0904–0.3122 g (mean 0.1913 g). Indices characterizing the various feeding phases, such as body index, scutal index, alloscutal index, growth index, engorgement index I and II, and the relative body mass index, were determined. The investigations demonstrated that the values of the morphometric traits in feeding phase I, II and III differe in I. ricinus females. Conclusions: The values of the morphometric features and indices can be helpful in identification of the parasitic stage of I. ricinus females removed from host skin, and assessment of the risk of infection of the host with various parasites injected with tick saliva at the respective feeding phases.