Ectoparasitism of castor bean ticks Ixodes ricinus (Linnaeus, 1758) on sand lizards Lacerta agilis (Linnaeus, 1758) in western Poland

Abstract

Background. Over 700 species of ticks are characterised by moderate to high host specificity, and a handful by very high host specificity, parasitizing upon a single host species. The rest are not host specific. One of them is the castor bean tick, which parasitizes all available terrestrial vertebrates including humans. Poland lacks tick species that are reptile-specific, since, as reported by K. Siuda (1993), these ectoparasites generally prefer endotherms, namely birds and mammals. However, the literature reports that the prevalence of castor bean tick infestation of local sand lizard populations is as high as 13.2 % – 40.4 %. Observations of different authors also indicate that outside the period of regular tick appearance on lizards, individual lizards can have very high tick loads, varying between several to over 100. Materials and Methods. The research was conducted in three separate study areas in western Poland: Żary, Zielona Góra and Nowa Sól. 606 specimens of sand lizards were captured, analysed and photographed. 222 (36.6 %) of them were infested with ticks. With each capture ticks were checked and removed. The lizards were caught by hand. Inter-group two-way and three-way ANOVA and Pearson correlation coefficients were calculated with the use of IBM SPSS Statistics 23 software. Threshold of statistical significance was set to α = 0.05. Results. In total 1339 ticks were obtained from lizards, all of which were castor bean ticks (Ixodes ricinus). 914 (68.2 %) were larvae, 424 (31.7 %) were nymphs and 1 (0.1 %) was an adult female. The highest number of ticks (778) was collected from lizards at Żary site. The most infested male from Żary was parasitized upon by 55 ticks, from Zielona Góra – by 46 and from Nowa Sól – by 15. In regard to females these numbers were 36, 34 and 15, respectively. The average infestation (defined as number of ticks) was higher for lizards from Żary than for those from Zielona Góra (p < 0.001) and Nowa Sól (p < 0.001), which also differed from each other in a statistically significant way (p = 0.001). Main effect of sex/age group turned out to be statistically significant, F(2.796) = 67.75; p < 0.001; η2 = 0.15. Hence post-hoc analysis was carried out and showed that males carried higher number of ticks than females and juveniles (p < 0.001). Females, on the other hand, carried more ticks than juveniles (p < 0.001). Conclusion. The research confirmed a significant role of sand lizards in propagation of Ixodes ricinus. It was shown that lizards were affected mainly by early develop­mental stages of ticks. The prevalence of tick infestation was 36.6 % – 58.1 % for Żary, 28.1 % for Zielona Góra and 13.8 % for Nowa Sól. The average tick load on sand lizards was 2.5 individuals. The highest number of them was collected from 58.5 % of males, 36.4 % of females and 5.1 % of juveniles. High tick infestation of males can be explained by their higher mobility, especially during mating season.