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The aim of the article is to estimate geographic variation of Ixodes ricinus (L., 1758) adults as a whole. Intraspecific variation of females and males has been studied in seven geographical localities of the eastern part of the species distribution range (fig. 1): Eastern part of the European range - Karelian Isthmus (A), plain of North-West Russia (B), Belovezhskaya Pushcha (C), western slopes of the East Carpathian Mountains (D); Caucasus-Asia Minor disjunctive range - northern slopes of the Greater Caucasus - Stavropol plateau (E), north-eastern slopes of the Greater Caucasus (F), north-eastern slopes of Talysh Mountains (G). Initiaily thirty characters were estimated statistically. The following ten characters of the thirty were used for comparison of geographic variation: length and width of spiracular plate, ventral width of gnathosoma, dorsal length of II—III articles of palps, length of tarsus I; the ratios of length and width of gnathosoma, of length and width of II—III articles of palps, of length and width of tarsus I, of length and width of apical cone of tarsus I; the sum of length and width of spiracular plate (fig. 2, 1-10: females; fig. 3, 1-10: males). The multidimensional scaling method by means of software packege SYSTAT was used for the assessment of relationships between seven samples on the basis of five morphometrical characters of both sexes. Fig. 4, 1, 2 show that both females and males have similar tendency of geographic variation: the greatest degree of differences revealed in both sexes from the Talysh Mountains (G); consolidation of populations in plains of Europe (A-C) and their considerable similarity with populations from north and north-eastern slopes of the Caucasus (E, F). Taking into account the partial discrepancy of relationships between populations (B and D) in sexes we have combined the data on corresponding characters of both sexes in the aggregate data base (fig. 4, 3). In this instance the scheme reserved tendency, similar in both sexes and became more accurate: all populations from European plains were joined in one group; population from Eastern Carpathian Mountains (D) differs considerably from other European populations. Population from the Talysh Mountains (G) shows the largest number of differences from other populations, both in sizes and proportions (tabl.). Population from Talysh Mountains has the largest sizes of organs. This population associated with relict Tertiary landscape and with recent conditions optimal ecological for this species. All other populations I. ricinus inhabit Holocene young postglacial landscapes.

The study of the micromammalian parasite complexes in the Belorussian part of the evacuation zone of the Chernobyl nuclear station revealed 13 species of Coccidiae and 30 species of ectoparasitic Arthropodes. Total increase of abundance and biodiversity of both parasites and their hosts was observed. The part of ectoparasites being epidemically hazardous was significaltly increased. An analysis of a long-term dynamics of parasite abundance reveals their adaptation to new conditions in the Belorussia.

Morphological differences between two chigger species, Neotrombicula autumnalis and N. caucasica stat. nov., are studied. New localities are reported for both species, for the second - also new hosts. Typical N. autumnalis from Moldavia precisely differed from the type series of N. caucasica from Georgia, but our collection on Western Caucasus included large number of intermediate forms. Attempts to draw a boundary between the two species by the linear discriminant analysis were not produced taxonomically reliable result. Thereby we decided to construct a picture of general similarities between all specimens and to classify them according to the positions of points on the diagram. The method of muitidimensional scaling with preliminary selection of characters was applied to produce such picture. The selection was carried out on the basis of cluster analysis, revealed a structure of correlations between standard measure-ments. The boundary drawn in this way was formalized by the construction of discriminant function. After that, it has become possible to consider a pattern of variation for different characters. Obvious tendency of a clinal variability, with increase of the sample means from west to east was observed in the majority of characters. And the cline included frequently the samples of both species. Serious taxonomical difficuities arose also from the strong difference between type series and other materials of N. caucasica. However, the basic diagnostic character of N. caucasica, the scutal width, does not correiate with Ip and lengths of setae and, consequently, it cannot be considered as just a "size" character subject to obvious intraspecific ecologically dependent variability. On the contrary, the difference between type and western N. caucasica could be easily interpreted as a result of ecologically caused diminution in the Georgian population of the species.

The phenomenon of Hydrachnidae association with the tick-borne encephalitic viruses complex has been found out during the study of the role of the Hydrachnidae in the arboviruses circulation. We investigated the fauna, studied the quantity variation and trophic relations of these arthropodes and blood-sucking Diptera. It was revealed no trophic relations between blood-sucking Diptera and mite species, where TBE straines were isolated from. On the basis of faunistic and virological study we suppose, that Hydroacarinae got an infection with the virus in the nymphal and imago stages, as well as larvae of mosquitos. Authors also note, that trophic relations between blood-sucking Diptera and chiggers (Trombidiidae) may be important in the arboviruses ecology.

Results of the seventy year long study of a species composition of fishes' parasites in basins of the Dvina river, Mesen' river and Pechyora river are summed up. During this time the 68 monogenean species were recorded in the first basin, 44 species - in the second basin and 45 species - in the third basin. The total number of monogenean species recorded in the examined region is 86 species.

The subfamily Benedeniinae consisting of 14 genera and including 57 species is concidered. The review includes a diagnosis of the subfamily, diagnoses of genera, lists of valid species, synonyms, hosts and localities.

Foundations of the Parasitic Contamination (PC) conception being considered as an element of biological contamination and manifested itself in urbanized ecosystems under an influence of diversiform ecological (amenable to anthropopressure) and socio-economical factors are presented. PC is regarded as the "superthreshold" contamination exceeding the "natural background" (i. e. the parasitological situation outside urbanized ecosystems). As a rule, PC is accompanied with events as follow: an increase (often explosive in character) of hosts' number of all ranks, of vectors numbers and finally of parasites' numbers (parasitic expression); a partial replacement of parasite faunas (parasitic succession); a capture of new territories and hosts (parasitic expansion). As a rule, all processes run synchronously. They lead to disturbances of evolutionary generated relations (quantitative and qualitative ones) in parasitic systems and thereafter to changes in a tension of epidemic, epizootic and epiphytotic processes. It is assumed, that rates of evolutionary processes going in parasitic systems is increased at the recent historical stage. Their entropy character is being changed: they often transform from more of less regulated (balanced) processes, which were achieved in a long course of component coevolution, into chaotic (unbalanced) ones. It is stimulated with a powerful and at the same time differently vectored anthropogenic pressure onto parasitic system components. It promotes inhibition processes involved in generating of a natural parasite-host mutual adaptation.

The female of Radfordia (Austromyobia) aegyptica Radford, 1951 (Acariformes, Myobiidae) from Dipodillus (Petteromys) campestis (Levaillant, 1857) (Gerbillidae) from Morocco is described for the first time.

Eimeria quadricornis sp. n. from an intestine of a sculpin Myoxocephalus quadricornis has an oocyst with yellow exterior granules. Oocyst size is 15.1-17.2 X 15.1-17.2 mkm, sporocyst size is 6.5 X 4.3 mkm.

The immune reaction of the carp to the ichthyophthirius infections of body and gills was examined.

Leptotheca schulmani sp. n. is described from a bladder and kidney of coregonid fishes, Coregonus lavaretus and C. albula, collected in the Onezhskoye Lake.

Summary is absent.

Summary is absent.

Summary is absent.