Preliminary Observations on Specific Adaptations of Exophilic Ixodid Ticks to Forests or Open Country Habitats

Abstract

Some features of three-host exophilic ticks important for their survival differ at the generic level in relation to the types of their habitat. Ixodes and Haemaphysalis are typical forest genera. Hyalomma is an open country genus, whereas Dermacentor and Rhipicephalus, having some features of forest ticks, are closer to the ticks of open country. Forest ticks encounter rather stable and favorable temperature, humidity and illumination conditions as compared with open country ticks. A few differences determining every-day survival, hostseeking. and reproduction of ticks are considered. (1) Tolerance to desiccation is very low in forest ticks and much greater in ticks of open country. (2) Lack of eyes in forest ticks (having, however, epithelial photoreceptor cells) and formation of eyes as special morphological structures in ticks of open country. (3) Capability of mating and insemination of unfed specimens both on and off hosts in forest ticks (Ixodes) and insemination of partially engorged females only on hosts by fed males in open country ticks. (4) Reciprocal sexual dimorphism where in forest ticks females have a larger body than males and in open country ticks this correlation is opposite. (5) Linear dependence between female weight and number of eggs laid is established in forest ticks after the female weight becomes higher than 50% of mean engorgement weight whereas in open country ticks linear dependence begins to reveal itself much earlier. (6) In forest ticks the compensatory growth occurs only during adult feeding whereas in open country ticks such a growth occurs both during nymphal and adult feeding. The adaptive nature of the above differences and their evolutionary trends have been hypothesized.

Influence of biotope on the distribution and peak activity of questing ixodid ticks in Hungary

“…It is well documented that I. ricinus and related spp. are associated with humidity and forested rather than afforested areas ( Gilot & Perez-Eid, 1998;Uspensky, 2002;Lindstrom & Jaenson, 2003 ), as indicated in the present results. The preference for xerophilic vegetation by D. marginatus and D. reticulatus ( Nosek, 1972 ;Estrada-Pena et al ., 1992 ) was also observed in Hungary.…”

“…In the group of forest ticks, different stages of Haemaphysalis and, especially, Ixodes spp. appeared to develop better under high humidity conditions ( Uspensky, 2002 ), such as those found in the dense, green vegetation along paths in forests, and only gradually on the fringes of meadows with partially dry vegetation. It was also apparent that all three Haemaphysalis species ( Nosek, 1971a( Nosek, , 1971bPerez-Eid et al ., 1993 ), as well as representatives of the genera Ixodes and Dermacentor , tend to be more abundant in areas with oak woods ( Nosek, 1972;Minar, 1992 ), a finding that is also connected to the presence of potential hosts in such areas ( Randolph, 1998 ).…”

“…This was confirmed by the present results, as temperature-dependent development rates may have caused later peaks of Dermacentor spp. as open country ticks ( Uspensky, 2002 ) in the cooler conditions of mountain meadows than in the warmer conditions of dry pastures. Another factor that may have triggered earlier questing of Dermacentor spp.…”

Tick- and fly-borne bacteria in ungulates: the prevalence of Anaplasma phagocytophilum, haemoplasmas and rickettsiae in water buffalo and deer species in Central Europe, Hungary

“…Anaplasma phagocytophilum was detected in all evaluated species, except buffaloes (Table 2 ). These buffaloes are kept in a grassland, which is an unsuitable habitat type for I. ricinus as a forest-dwelling tick species [ 20 , 21 ]. This is the most likely explanation, why buffaloes did not have A. phagocytophilum infection, while its prevalence was high in game animal species hunted in forests (Table 2 ).…”

First report of adult Hyalomma marginatum rufipes (vector of Crimean-Congo haemorrhagic fever virus) on cattle under a continental climate in Hungary

“…One factor that may have contributed to this is that Hyalomma spp. prefer open country habitats [5], therefore are more likely to attach to cattle which permanently graze on pastures. Similarly, D. reticulatus as an open country tick species [5] was significantly (Fisher’s exact test: P < 0.0001) more prevalent on cattle during the present survey, than on game animals partly with forested habitats.…”