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Species composition and structure of ectoparasite arthropod communities were examined all year round six years in the bank vole Clethrionomys glareolus, Ural wood mouse Apodemus uralensis and the common shrew Sorex araneus in forests of the Ilmen'-Volkhov depression. In total, 4500 host samples have been examined and all ectoparasites have been collected. The species composition of ectoparasite community in small mammal species are as follows: the bank vole — 29 insect, tick and mite species, the common shrew — 23 species, the Ural wood mouse — 16 species. In forest biotopes, many temporary ectoparasitic species occur on several host species living in the same habitats under a forest canopy and contacting each other. A parasitic supracommunity in the ecosystem examined has a pool of temporary ectoparasites, which is available for all the community of small mammals. A role of different rodent and shrew species are hosts of insects and ticks changes depending on a density of potential host populations and numerous other environment factors.

A retrospective estimation of the abundance dynamics of the taiga tick Ixodes persulcatus in mixed coniferous and leaf-bearing forests of the Udmurtia Republic in the period 1957—1986 was carried out. A possibility to estimate the absolute number of all stages of I. persulcatus based on relative indices. Females of I. persulcatus lay 20 250 eggs per 1 hectare, and this number of eggs gives birth to 15 000 larvae. From this number, 7870 larvae hibernate and 6550 individuals became fed. The number of nymphs is 5930, among which 5930 individuals live up to spring, and 1390 became fed. The number of adult mites in autumn is 1250; in subsequent spring this number decreases to 780. The mean number of engorged females is 8. The mortality rate of ticks caused by the deficit of hosts increases from preimaginal stages to adults; for larvae, nymphs and imago this index is 16.6, 72.8, and 97.9%, respectively. Quotas of individuals with 3-, 4- and 5-year life cycle among the unfed imago are 70.4, 28.0, and 1.6%, respectively.

In the course of 5-year stationary investigations of the common shrew Sorex araneus in the north part of the Novgorod oblast, 12 flea species have been recorded on this host. Among them, Palaeopsylla soricis and Doratopsilla dasycnema are specific parasites of small insectivores, including the common shrew. Hystrichopsylla talpae is a polyxenous species, parasitizing both rodents and insectivores. Other 9 flea species are not common parasites of S. araneus and apparently have come to this host from other mammal species inhabiting the forest biotopes in the area of investigation. P. soricis and D. dasycnema have similar phenology of parasitism. These fleas appear in spring (April), are present during summer and autumn and disappear in winter. During a year, the abundance of these species shows three pikes, which correspond to three generations: spring (April), summer (June—July) and autumn (September—October) generation. The first species dominates in spring (April—May) and in the autumn-winter period, while the second species predominates in summer. These two species comprise over 90% of total number of fleas collected and determine general dynamics of the flea number on the shrews; during the year the flea number has a sinusoidal increasing from spring to autumn and minimum in winter.

Host-parasite relationships of Hyalomma species of the world fauna are analyzed. The majority of species infests predominately various mammals. Birds and reptiles are used as preferred hosts by several Hyalomma species, and only on certain stage: adults of H. aegyptium parasitize tortoises; immature stages of H. marginatum parasitize birds. It is hypothesized that relationships of H. aegyptium adults (subgenus Hyalomma s. str.) with reptiles are secondarily in origin. Immature stages of H. aegyptium retain the primary wide diapason of hosts, which are various small mammals, birds and reptiles. The life cycle of this species is the three-host type that is considered as a primary type in ixodid ticks. A typical scheme of relationships with their hosts in all well-examined Hyalommina species has following features: the adult stage parasitize large and medium sized mammals, immature stages parasitize small mammals, three-host life cycle. A variety of preferred hosts and types of life cycle is observed in the subgenus Euhyalomma. All species of this subgenus can be arranged into two groups. In the first group, the immature stages infest only small mammals and birds, and the adults parasitize large mammals; this type of host preferences is probably primary host-parasite relationships of Hyalomma. This group includes: H. albiparmatum, H. asiaticum, H. excavatum, H. franchinii, H. impeltatum, H. impressum, H. lusitanicum, H. marginatum, H. nitidum, H. schulzei, and H. truncatum. Hyalomma marginatum and H. schulzei are two-host species; H. excavatum is two- or three-host tick. All the remaining species (except H. albiparmatum, which life cycle is unknown) are three-host ticks. In the second group, the immature stages as well as the adult stage parasitize large mammals. This group includes: H. dromedarii, H. anatolicum, and H. scupense. These species are two- or one-host ticks.

Similar strategies to preserve a species were evolved independently in different groups of Coccidea. Polyenergid oocysts and tissue cysts are found in representatives of the orders Protococcidiida and Eimeriida. Hypnozoits are found in Karyolysus lacerate and Plasmodium vivax; transovarial transmission of parasites occurs in life cycles of Coccidea of the genera Karyolysis and Babesia. Formation of heteroxenity in groups of Coccidea apparently was developed by different ways and in different periods. In some groups (Cystoisospora, Toxoplasma, Aggregata, Atoxoplasma, Schelackia, Lankesterella, and Calyptospora), recent definitive hosts were initial hosts; in other groups (Sarcocystis, Karyolysus, Haemogregarina, Hepatozoon, Plasmodium, Haemoproteus, Leucytozoon, Babesiosoma, Theileria, and Babesia), intermediate hosts were initial hosts.

The analysis of the general structure of orthonectids shows that free-living sexual specimens are bilaterial, while the parasitic Plasmodium is anaxonic. All worm-like stages in the life cycle of dicyemids are characterized by monaxonic heteropolar symmetry, while their infusorioform is bilaterial.

Mathevolepis junlanae sp. n. from shrews (Sorex spp.) of Far East is described given. The new species occupies an intermediate position between the Palaearctic species M. petrotschenkoi Spassky, 1948 (total number of proglottids — 4) and M. skrjabini (Sadovskaya, 1965) (10—12 segments in a series) by the number of synchronously developing proglottids (2—4). The new species differs from M. larbi Karpenko, 1982 by the structure and measurements of copulative apparatus in proglottids. In M. larbi, vagina S-shaped, vagina length 0.147—0.154 mm, cirrus length 0.146—0.149 mm, and cirrus bursa reaching aporal excretory vessels. M. junlanae sp. n. has cirrus bursa slightly crossing center line of sexually mature proglottids, cirrus about half as long (0.084—0.092 mm), and smaller sac-shaped vagina (0.075—0.10 mm). The new species differs from the Nearctic representative M. macyi (Locker et Rausch, 1952) by lesser measurements of cirrus bursa (0.12—0.14 mm versus 0.4 mm) and a fewer number of proglottids in series (2—4 versus 5—7).

The genus Copiatestes Growcroft, 1948 is revised. It is shown that Copiatestes filiferus (Leuckart, in Sars, 1885), Syncoelium cypseluri Yamaguti, 1970 and S. regulaci Villarreal et Dailey, 1993 are junior synonyms of the type species C. thyrsitae Crowcroft, 1948. The genus Copiatestes is monotypical.

Spores of microsporidia have been recovered in 5 specimens of 13 ixodid ticks Ixodes ricinus from various populations of the Republic Moldova collected in spring of 2004. Microsporidia were detected by meand of fluorescent microscopy. Intensity of infection was 3—6 spores per a micropreparate from one mite. Based on spore size, character of staining and the presence of diplocarion, these spores are referred to the Nosema-like type. Low intensity of infection probably is caused by that fact that ticks were collected in spring period and were unfed.

The influence of the intestine cestode Botriocephalus gregarius on the antioxidant enzyme system in the liver and muscle of its host, the Black Sea flounder Psetta maxima maeotica, was studied. The significant increase of superoxiddismutase activity in examined tissues and changes of catalase and peroxidase activities were detected. High correlation (r > 0.6) between enzyme activities and the parasite number was noted. The possibility to use antioxidant enzyme activity as biomarkers of the parasite invasion in fish is discussed.

A redescription and comparative diagnosis of Gyrodactylus atherinae Bychowsky, 1933 is made based on the material collected of В.E. Bychowsky from Atherina boyeri pontica caught near Karadag (Black Sea) in summer of 1947.

Larvae of anisakid nematodes of a new morphological type from the anadromous mikizha Parasalmo mykiss (Salmonidae) are described. The larvae have 6 sclerotized cogs on the cephalic end of the body. These larvae are referred to the tribe Lappetascarini Rasheed, 1965 as forms with uncertain generic membership.

Summary is absent.