[Influence of the phase of the number and demographic structure of the water vole population on its infection by helminthes].

In this work we have analyzed results of the long-term investigations of the helminthes distribution in the various demography groups of the water vole population (Arvicola terrestris L.) in North Baraba (Novosibirsk region). The data on the dominant parasites of these rodents: trematodes Notocotylus noyeri (Joyeux, 1922), cestodes Limnolepis transfuga Spassky et Merkuscheva, 1967, nematodes Capillaria wioletti Ruchljadeva, 1950, Longistriata minuta (Dujarden, 1845) and Heligmosomum costellatum (Dujarden, 1845) have shown that the number of parasites in biocenosis are connected with different factors, such as the demographic structure of the host population, the alternation of hosts number and conditions of the environment (dry and damp phases of the climatic cycle). In the dry phase the main parasitize load N. noyeri, L. transfuga and C. wioletti connects with the breeding group; in the damp period - with immature rodents. Independently of the phase climatic cycle and the density of the water vole population the great bulk of nematodes L. minuta and H. costellatum was uncovered of the immature individuals. In any case the number of helminthes changed synchronously with such of the its host.

[Endo- and ectoparasites as factors influencing variability of the humoral immunity response in a natural population of red vole (Clethrionomys rutilus)]. / Endo- i éktoparazity kak faktory izmenchivosti reaktsi gumoral'nogo immuniteta krasnykh polevok (Clethrionomys rutilus) v prirodnoi populiatsii.

Based on the five-year population study of red voles Clethrionomys rutilus Pallas in southern West Siberia, we analysed the distribution of two predominating species of parasites (tapeworms Hymenolepis horrida and immature instars of ticks Ixodes persulcatus) in different demographic groups of the host, and seasonal changes of their incidence in the population. We assessed primary humoral immune response of the voles (splenic antibody-forming cells) to antigenic challenge (injection of sheep erythrocytes) in respect to occurrence of these parasites. It was revealed that infection with H. horrida significantly reduced the numbers of antibody-forming cells in immature summer-born voles. In contrast, immune responses in immature and mature voles, which where parasitized by I. persulcatus at the moment of capture, were significantly higher as compared to non-infected hosts. The possible mechanisms of influence of parasites on variability of immune reactions of voles in the population under study are discussed.

[Paranoplocephala longivaginata sp. n. (Cyclophyllidea: Anoplocephalidae)--a new cestode from rodents of the Western Siberia]. / Paranoplocephala longivaginata sp. n. (Cyclophyllidea: Anoplocephalidae)--novaia tsestoda ot gryzunov Vostochnoi Sibiri.

A new species of anoplocephalidean cestode Paranoplocephala longivaginata sp. n. from some rodents (Clethrionomys rutilus, Sciurus vulgaris) of the Western Siberia is described. The new species differs from formerly known species of the genus Paranoplocephala by a structure of copulatory organs: the length of cirrus and the length of vagina exceed the length of genital bursa more than 1.5 times; the internal surface of the vagina is covered with hair-like bristles along all its length.

[Parandrya feodorovi gen. n., sp. n.--a new cestode (Cyclophyllidea: Anoplocephalidae) from voles in Siberia]. / Parandrya feodorovi gen. n., sp. n.--novaia tsestoda (Cyclophyllidea: Anoplocephalidae) ot polevok Sibiri.

A new genus and species of the anoplocephalid cestodes, Parandrya feodorovi gen. et sp. n. are described from the Western and Eastern Siberia voles. The new genus Parandrya is distinguished from the genus Andrya Railliet, 1893 by the presence of the cellular form of the uterus. The new genus also differs from other known genera of anoplocephalid cestodes associated with Rodentia, which have a single genital apparatus and cellular uterus, by the transformation of the external receptaculum seminis into the prostatio gland.