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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.
The Palearctic three-host species Dermacentor reticulatus contributes to the circulation of numerous pathogens in the environment. Reduction of its abundance may therefore decrease the risk of tick-borne diseases in a given area. The aim of the study is to determine the effect of various concentrations of three pyrethroids – deltamethrin (D), cypermethrin (C), and alpha-cypermethrin (AC) on the development of D. reticulatus eggs and larvae. 217 engorged D. reticulatus females were examined in the investigations. After the feeding period, they were sprayed with 0.015625%, 0.03125%, 0.0625%, and 0.125% solutions of D, C, and AC, and kept at a temperature of 25oC and 90% relative humidity throughout the preoviposition and oviposition periods. Eggs laid by females were kept in the same conditions until larval hatch. Based on the results obtained, parameters of the course of maturation and oviposition, as well as parameters of embryonic development, were determined. The investigations showed that the pyrethroids tested prolonged the egg maturation period, reduced the number and weight of eggs, and caused disturbances in embryogenesis in D. reticulatus. Upon treatment with as little as 0.015625% AC, larvae did not develop and all eggs died 1–2 days after oviposition. C led to a decreased percentage of normal larval hatch – 31.96%, 15.51% and 12.5%, respectively, after using three increasing concentrations (control 98.15%), and a high rate of egg and embryo mortality. The least detrimental effect on the D. reticulatus maturation and embryonic periods was exerted by deltamethrin (82.74%, 84.37% and 16.80% of normal larvae in treatment with the three concentrations). Morphological anomalies were observed in larvae during the experimental period. AC appeared to have the most toxic effect during the maturity and egg development periods, while C exhibited lower toxicity. Application of these pyrethroids in engorged D. reticulatus females exerts distant effects that lead to substantial reduction of tick offspring abundance.
Investigations into the abundance of adult D. reticulatus in relation to the effect of climatic conditions (temperature, humidity) on host-seeking behaviour were conducted during the autumn (September-October) and spring (May) activity peaks in 2008–2009 in eastern Poland (51°25’N). The study was conducted in the same habitat where similar examinations were performed in 1999–2000. A comparative analysis revealed that the abundance of D. reticulatus had almost doubled within 10 years. Analysis of data on the humidity and temperature conditions prevailing during tick collection, and on tick abundance in the respective study periods in 1999–2000 and 2008–2009, as well as absence of climatic changes over many years, indicate that the increase in the numbers of ticks may have been a result of a multitude of other factors, e.g. weather or environmental conditions favourable for ticks and their hosts. The substantial differences in D. reticulatus abundance observed during the autumn activity peak (an increase from 126 and 128.6 specimens per collection in 1999 and 2000, respectively, to 247.3 in 2008) demonstrate the considerable effect of the biotic and abiotic conditions prevailing during the development of young and adult stages on the abundance of this tick species. The activity of adult D. reticulatus ticks in the autumn was 2.7-fold higher in comparison to that observed during the spring collection; the difference was statistically significant (p<0.0001). Females dominated in both seasonal activity peaks. The ratio between females and males during the spring and autumn peaks was 3.31:1 and 1.05:1, respectively. The increase in the abundance of the D. reticulatus population implies a higher risk of transmission of tick-borne diseases in the study area, and the necessity to develop and implement effective prevention methods and tick control programmes.
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