Relative density of host-seeking ticks in different habitat types of south-western Slovakia

Abstract

Ixodes ricinus is a vector of microbial pathogens of medical and veterinary importance in Europe. Recently, increasing abundance of ticks has been observed in urban and suburban areas. The aim of this study was to investigate the tick species composition and examine correlations between local environmental variables and the relative density of host-seeking I. ricinus in two habitat types. Questing ticks were collected along six 100 m(2) transects in urban/suburban locations of Bratislava town, and in a non-fragmented deciduous forest in the Small Carpathians Mountains (south-western Slovakia) during 2011-2013. In total, 6015 I. ricinus were collected (3435 and 2580 in the urban/suburban and natural habitat, respectively), out of which over 80 % were nymphs. Haemaphysalis concinna comprised 1.3 % of the tick collections. Peak I. ricinus nymph and adult host-seeking activities were registered in April-June. Spatial and temporal variation in tick relative density and differences in the subadult/adult ratio were observed between habitats and between locations within the same habitat type. The relative density of questing I. ricinus nymphs correlated negatively with altitude, geographical aspect and saturation deficit in a 64-day period comprising the 8-day period including the date of tick sampling and previous 56 days. No significant correlation was found between roe deer density and questing nymph density. The study revealed the presence of abundant I. ricinus populations in green areas of Bratislava, suggesting a risk of exposure of town dwellers and domestic and companion animals to potentially infected ticks.

Keywords: Acari; Ixodes ricinus; Questing activity; Relative density; Urban habitat.