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Attention was given to the necessity of control of the infected part of the population of vectors of transmissible infections. For this purpose it was suggested to investigate the nature of parasitism of the agent, to look for synergists of their pathogenic effect and to study the ecology of vectors in order to use control measures against the infected part of the population in the sites of aggregation.

Foci of mycosis of С. p. pipiens and С. p. molestus caused by the parasitic fungus Entomophthora conglomerata Sorok. were found out in basements flooded with water. The conditions prevailing in the foci, sites of infection of mosquitoes and seasonal changes in the epizootic process are described. Developmental periods of conidiospores in mosquitoes were established experimentally. Entomophthorosis epizootia was found to limit the possibilities of mosquitoes to scatter from the hatching sites and to reduce the number of biting females in the population.

The content of the total protein, residual and amine nitrogen, urea and ammoniac depends on the physiological state of the warble fly larvae of the reindeer. Metabolism of nitrogen-containing compounds carries out most intensively in the growing organism and during the moulting period. The moulting period is characterized by the fall in the total protein, residual and amine nitrogen and increase of the ammonias and urea.

Daily rhythm of detachment of engorged larvae of Ixodes ricinus L. and Hyalomma anatolicum Koch is regulated by photoperiod. In photoperiodic conditions (16—20 hours of light p. d.) the maximum of detachment in H. anatolicum occurs at the beginning of photophase (the first 4—8 hours), but in I. ricinus it occurs at the second part of photophase (12—16 hours after the light is on). The rhythm of detachment is regulated according to the processes of endogenous circadian nature which are maintained in the continuous light and are species-specific. The phase entrainment of detachment in continious light is also influenced by biorhythms of hosts.

During the feeding of larvae and nymphs of A. lahorensis haemorrhagic inflammation develops in the rabbit's skin. Lymphocytes and macrophages are the dominant cell elements in the reaction while during the feeding of nymphs eosinophilous leucocytes are observed in great number in the infiltrate. Around the oral parts of the tick an infiltration of collagenous fibres of the connective tissue is formed, which serves for a more firm attachment of the parasite, while beneath the proboscis a light band is formed from which the tick sucks the food substratum. By the end of the feeding of nymphs III in the place of skin affection a crust can be formed on account of the host's atrophied tissues, and in the integuments there are formed necrotic foci due to the hystolitic and toxic effect of the saliva.

The tick encephalitis virus was found to multiply more intensively in ticks developing without diapause. Thus, in larvae developing with diapause, in 4 and 8 weeks after they feed on infected animals, the virus titers were 3.0 and 3.5 lg LD₅₀ respectively. At the development without diapause the titers were 4.3 and 5.3, respectively (P < 0.05). The virus titers in infected nymphs developing without diapause were 2.5 to 3.9 lg LD₅₀ higher than those of the diapausing individuals. In diapausing larvae and nymphs the tick encephalitis virus remained for a long time (8 to 10 weeks) without fall of titers. The fall of virus titers was not recorded either during the moulting of larvae for nymphs and nymphs for imago but in hungry ticks, which were maintained for a long time at 18 to 23 C, the amount of virus gradually diminished.

The paper contains descriptions of four new species of parasitic isopodes of the genus Cymothoa Fabricius, 1787 collected in fishes from waters of the Indian Ocean off Australia.

Toxoplasma gondii was found to cause an appearance of cells with a changed number of chromosomes in the bone marrow of infected white rats. Besides the increase of aneuploid and polyploid cells the infection with toxoplasms inhibits the mitotic activity in bone marrow of rats. The similar changes were observed in blood leucocytes of toxoplasmosis patients.

A new species of microsporidians, Stempellia lairdi sp. n., was found in larvae of Tabanus autumnalis L. from Ukraine. It affects the muscular tissue and haemolymph of horse fly larvae. Spores of the species are oval, egg-shaped, 1.8—7.6X1.2—3.8 µ in size. The species is pathogenic and causes the mortality of infected larvae.

Of 6 species of black flies from 6 water bodies microsporidians P. simulii, P. debaisieuxi and Th. varians are reported only in four species, B. maculata, Sch. pusilla, S. morsitans and S. argyreatum. Peculiarities in the infection of black flies larvae with microsporidians in various types of water bodies within a season were established. Under experimental conditions P. simulii and P. debaisieuxi cause mortality of larvae (68 to 87%) and decrease in the emergence of imago (5 to 19.6%).

The development of the additional membrane (exocyst) from the caudal appendage in diplocysts does not change essentially the structure of the cyst's wall in metacestodes of the genus Aploparaksis. In cytoplasmic connections between cytons and the surface syncytium there are two autonomous enough systems of transport: microtubes opening to the surface of tegument and matrix of bridges which proceed to the matrix of external syncytium. In addition to cytons, in the cyst's wall there are cells with an enlarged granulated endoplasmic network, which are miofibroblasts, secretory cells performing an unclear function, protonephridia and cells limiting the cavity of the cyst of the layer. Differences in the larval morphology of both species are quite negligible and can be due to their age peculiarities.

Unlike the stem eelworms of cultivated plants, which have n=12, the stem eelworms of wild plants (Picris sp., Taraxacum officinale, Hieracium pratense, H. pilosella, Cirsium setosum and Falcaria vulgaris) possess high chromosomal numbers (from n= 19 in the first to n= 28 in the latter). Due to this the stem eelworms of wild plants must be separated from the collective species Ditylenchus dipsaci. Apparently these forms of stem eelworms are distinct species polyploid in their origin.

6 species of black flies were collected in the territory of Karachaevo, the Cherkes ASSR. Of them, Odagmia monticola and Obuchovia popovae are mass species.

Effect of microsporidiosis on the fecundity of hosts A. c. caspius was studied. The calculation of eggs in hatches has shown that females developing from infected eggs lay 2—3 times lesser eggs than non-infected ones. Besides, the number of females laying eggs decreases considerably. Despite the females of mosquitoes suck blood before each egglaying the disease, which proceeds at their larval stage, affects greatly their fecundity. Additional feeding of females cannot compensate completely the distrubances caused by microsporidiosis.

The assimilation of the radioactive isotopes Fe⁵⁹ and Zn⁶⁵ by Eimeria tenella was studied. It has been established that both radioisotopes are included into the structures of E. tenella. Fe⁵⁹ has been found to be assimilated by the parasite more intensively than Zn⁶⁵.

Three new species of Ciliata of the family Urceolariidae were found as follows: Paratrichodina voikarensis sp. n. on the gills of Coregonus nasus and C. peled; P. uralensis sp. n. on the gills of the sterlet and Trichodina percae sp. n. in the nasal cavities of tha perch. Figures and descriptions of the new species are given.

On the basis of the structure of the terminal parts of the genital system Hemiurus macrouri Gayevskaya, 1975 is transferred to the genus Glomericirrus. G. ulmeri Campbell and Munroe, 1977 is considered as a synonym of G. macrouri (Gayevskaya, 1975). It is noted that G. macrouri occurs but rarely (1.1%) in Coryphaenoides rupestris from the northern part of the Middle Atlantic ridge.

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Summary is absent.

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Summary is absent.