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|ŠUMARSKI LIST 5-6/2014 str. 62 <-- 62 --> PDF|
pedunculate oak and hornbeam (as. Carpino betuli – Quercetum roboris Ht. 1938) on locality Haljevo. All ticks collected on home pets belonged to same species, that is Ixodes ricinus. Ixodes ricinus was also the only tick species recorded on roe deers (Pintur et al. 2012) and on birds (Trilar 2004). Ixodes ricinus has been sampled on many bird species during field studies all over Europe, and it has been found that bird species are very important in the spatial spread of this species (Tovornik 1990). Results of this study are in agreement with results of many similar field studies conducted in Europe where the species I. ricinus was found to be the most abundant member of local tick fauna. Habitat suitability for Ixodes ricinus is relatively stable in Europe (Estrada-Pena and Venzal 2006), and that is the reason for their wide geographic distribution within the latitudes 65o and 39o N, inhabitting the area from Ireland and Portugal eastward to the Volga River in Russia and southward to North Africa (Jaenson and Jensen 2007). In adult stage, I. ricinus was the most abundant in April, whereas in larval stage it dominated in July. From March to mid-May, nymphs and adults of I. ricinus has been sampled, whereas in July mostly larvae and nymphs. These results are in line with seasonal dynamics of certain developmental stages of I. ricinus, because in midsummer in July, diapause often affects the adults (Hillyard 1996). However, the activity periods are affected by dry conditions and host availability (Mikačić 1965, Hillyard 1996). Availability of roe deer as host is very significant, because they are the most important wild hosts for adult stage of I. ricinus on the area of central Europe (Tovornik 1988a, Pintur et al. 2012). That is probably the reason of large number of sampled ticks in Haljevo Forest, where the population of roe deer is also high. Roe deer are animals with an extremely small circulation radius, therefore they constantly live in the same part of the forest, and as a consequence, fragmented forests and their edges with roe deer have very abundant tick populations (Tovornik 1988a). Among all European tick species, I. ricinus is the most widely distributed (Milutinović et al. 2006). Wide ecological plasticity makes it one of the main vectors of infectious diseases within humans, consequently causing highest human health threat in Europe (Punda-Polić et al. 2002, Lindström and Jaenson 2003, Jongejan and Uilenberg 2004, Estrada-Pena and Venzal, 2006). Ixodes ricinus is one of the most widely distributed tick species in continental and Mediterranean part of Croatia (Krčmar 2012). In the area of northern and northwestern Croatia, nine species of hard ticks have been identified (Mikačić 1968, 1969, Tovornik 1976, 1988b, 1991), within these, four of them within this study in the area of eastern Croatia. Haemaphysalis concinna takes second place in the abundancy list, and all specimens belonging to this species were sampled in Haljevo Forest. Recently, three years ago, this species was sampled for the first time on the area of eastern Croatia, in the forest of sessile oak and hornbeam (as. Epimedio-Carpinetum betuli /Horvat 1938/Borhidi 1963) at the locality of Mikleuš (Teni 2012). Together with these findings from eastern Croatia, there are only two more records of this species in Croatia, one in the northern Croatia (Dekanovec), and the other on Krk island (Tovornik 1988, Hassl 2003). Species from the genus Dermacentor are represented with only 0.47 % in collected sample (Table 1). In Great Britain and Ireland D. reticulatus occurs at low densities (Ogden et al. 2000) which complies with our results. However, in Hungary this species is very abundant, as well as in the area of Tuzla canton in Bosnia and Herzegovina (Földvári and Farkas 2005, Krčmar et al. 2014). In three habitats, pond edges, melioration channels near to agricultural land and meadow near to city pools, only 3.48 % of ticks have been sampled. The most likely reason for that is the fact that forest habitats provides a buffering effect against climatic extremes, with less variation in temperature and humidity compared with more open habitats (Lindström and Jaenson 2003). In park in the center of the Beli Manastir, during the whole research period, no ticks were sampled. There may be more reasons for that, one of the seemingly important one is that pet owners are taking good care of their pets using different repellents against ticks, and they rarely bring out their pets in city park. In the city of Beli Manastir typical housing by 90 % are low or high single-storey houses with smaller or bigger courtyards and that is a logical reason why owners have no need to bring their pets into parks, or they do it on rare occasions. In this study, H. inermis is recorded for the first time in continental Croatia. Until this research this species was sampled only in the Mediterranean part of Croatia (Mikačić 1965, Krčmar 2012). Haemaphysalis inermis mainly inhabits deciduous and mixed forests (Hillyard 1996), and that is probably the main reason why it was sampled only in the forest of common oak and hornbeam on locality Haljevo. Another possible reason for first finding this tick species in continetal Croatia is lack of more similar studies throughout the country. Additionally, global warming, as climate related changes, may affect the geographical distribution of ticks (Hornok and Farkas 2009) and may also play role in the changes of tick species distribution in the country diverse as Croatia. The largest amount of tick fauna similarity existing among five different habitats turned out to be within pond edges and meadow near to city pools, since these habitats contain only one species, I. ricinus. Large percentage of I. ricinus on certain types of habitats indicates little diversity of tick fauna. The reason is probably in the fact that I. ricinus is least sensitive on temperature changes, while other species are sensitive to various extent (Ploj 2007). On the other hand, in the areas where temperature is not a limiting factor, the rainfall becomes the primary factor, defining the tick fauna diversity (Estrada-Pena and Venzal 2006).