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Summary is absent.

Together with a story of the author's earliest visit to Leningrad and first meeting with the late Academician E. N. Pavlovsky, this contribution outlines subsequent developments concerning innovative approaches to the control of Culicidae of medical importance, with particular attention to a major field trial on the atoll of Funafuti, Tuvalu.

The paper presents analysis of literary data on experimental infection of 11 species of gamasid mites and 10 species of fleas with tick-borne encephalitis virus (ТЕ) and experiments on transmission of the virus to animals by 9 species of gamasids and 14 species of fleas. Nearly all investigated species can perceive the virus, preserve it from some hours to two months and transmit it to animals within a period of 24 hours to two months after experimental infection. The fact of transmission of the virus to animals was established by the presence of recipients in the brain or by the presence of antibodies. To settle the question of the possible participation of gamasids and fleas in the circulation of the virus ТЕ in nature threshold doses of the virus for infection of mites and fleas of different species, mechanism of transmission of the virus to animals by gamasid mites, facultative haematophags, titers and terms of virusemia in animals which obtained the virus from gamasid mites or fleas should be established.

The paper presents results of virusological and electron microscope studies of the reproduction of viruses of tick-borne encephalitis and Povassan at mono- and mixed persistent infection of explants of imaginal tissues of Hyalomma anatolicum and H. dromedarii with these viruses. The virus reproduction in explants was observed within 208 to 217 days after the infection. Joint reproduction of two model viruses within 1—2 months after the infection can take place and after that the inhibition of the reproduction of one of the viruses. This inhibition can be of cyclic character.

The results of titration of adult virus infected ticks of Ixodes persulcatus are given. The ticks were collected in various natural nidi of tick-borne encephalitis and individually fed on laboratory animals. The results of titration of ticks of the same species primarily infected on laboratory animals during virusemia are given as well. Changes of the virus titer in engorged ticks were observed till the egg production. A role of the presence of virus in engorged ticks for the process of the agent circulation in natural nidi is discussed.

A definition of susceptibility of an arthropod to an infectious or invasion agent is given. The susceptibility means a capacity of the arthropod for infection in a result of which the agent either completes a part of its life cycle in the organism of its invertebrate host or reproduces repeatedly in the organs and tissues of its internal medium causing or not causing a noticeable damage. On the model of the tick O. papillipes and Q. fever agent there were shown differences in the resistance of arthropods to Rickettsiae depending on the developmental phase of the invertebrate host. Under otherwise equal conditions the susceptibility of nymphs of O. papillipes to С. burnetii was in nymph II 146 times, in nymph I 280 times and in larvae 50 000 times less than in nymph IV. It has been established that nymphs I, II, and IV engorge blood only 2.5, 14 and 50 times more respectively than larvae. It shows that the success of infection depends to a larger extent on the degree of susceptibility of an arthropod to a corresponding agent than on the quantity of engorged infected blood. The formula of estimation of agent concentration necessary for successful infection of 50 per cent of ticks is given.

On the basis of parallel study of natural and cultivated preimaginal phases of the genus Dermacentor differential diagnoses of three palaearctic subgenera were worked out: Asiacentor Filippova et Panova, 1974, Serdjukovia Dias, 1963 and Dermacentor (s. str.) 1844. The diagnoses are also based on peculiarities of chaetotaxy and other characters of small sizes. On the basis of identification of species of the subgenus Asiacentor on immature phases new sites of their distribution were found out: D. pavlovskyi: in the Issyk-Kul hollow, in the foothills from the side of Terskey-Alatau ridge; D. montanus: in Gissarsky ridge in the environs of Lake Iskander-Kul. Remoteness of these cites from the distribution borders known earlier point to ecological and geografical differential peculiarities of the subgenus and its species.

During the period of 1955 to 1983 805 fleas of 7 species were collected from 3143 bats of 13 species in Turkmenia, northern and south-western Tadjikistan, southern Kirghizia and South Kazakhstan. There were obtained data on the abundance and adaptation of 5 species of fleas (Ischnopsyllus petropolitanus, I. octactenus, I. plumatus, Rhinolophopsylla unipectinata turkestanuca, Nycteridopsylla oligochaeta) to different species of bats. Observations were conducted in spring, autumn and winter in such shelters of bats as caves, galleries and buildings. Fleas were found to parasitize bats in warm galleries and caves situated at a height of 600 to 1200 m above sea level and were absent from cold galleries and caves at a height of 1500 to 2000 m above sea level. No findings of fleas on single bats are reported. In buildings fleas were found on bats only at the time of high summer temperatures. The main hosts of Rh. unipectinata turkestanica and I. petropolitanus are Myotis blythi and Plecotus austriacus, respectively. Fleas were scanty or absent at all in colonies of bats of the genus Rhinolophus in which animals are usually at some distance from each other. More compact colonies of Myotis blythi, Plecotus austriacus, Pipistrellus pipistrellus and Eptescus serotinus are, apparently, more suitable for fleas of the family Ischnopsyllidae.

Seasonal changes in the distribution of fleas in external burrow passages of great gerbil were studied in Repeteksky State Reserve in East Kara-Kum (Turkmenia). These changes are associated with migrations of fleas in search of temperature optimum. The peak of migration activity was recorded in March with the peak of abundance in external passages of burrows of Xenopsylla hirtipes.

For the first time comparative study was conducted of the ultrastructure of promastigotes of Leishmania major and L. tropica in the organism of Phlebotomus papatasi which for the first species of Leishmania is and for the second species is not a natural invertebrate host. During the bloodsucking on Mesocricetus auratus experimentally infected with Leishmania sandflies perceive amastigotes of both L. major and L. tropica. In the midgut of the sandfly both species of Leishmania pass into the stage of promastigote (therefore, this phenomenon is not defined by species-specific factors). However, further fate of promastigotes of L. major and L. tropica in Ph. papatasi is different. L. major has its normal cycle of development in the intestine of the sandfly and preserves its all ultrastructural peculiarities. Promastigotes of L. tropica, on the contrary, display in the midgut of Ph. papatasi signs of degeneration which are expressed in break of their normal ultrastructure (changes in the shape of cells, break in cell division, thickening or thinning of intracytoplasmatic formations, especially of mitochondria, intensified vacuolisation of cytoplasm, changes in the structure of nucleus and kinetoplast, and others). All these data indicate in an indirect way that the intestine of Ph. papatasi is a favourable medium for L. major and unfavourable one for L. tropica.

Antibodies to Toxoplasma in the reaction of indirect hemagglutination were found in 8 species of mammals and 2 species of birds. Carriage of antibodies to Toxoplasma in house mouse, common fox, bald coot, and rock-dove was first recorded from Turkmenia. Analysis of the infection with Toxoplasma according to species, habitat of antibodies carriers, their ecology, age, sex and season of investigation is given.

The paper concerns the study of the effect of migrations on the infection of birds with parasitic Protozoa of blood. The author has used extensive data on the migration of birds along the Kurish spit and age-seasonal analysis of infection of investigated populations with blood Protozoa. The migration of birds to zones of warm and mild winter is an important factor for their infection with Plasmodium, Haemoproteus and Trypanosoma. The infection of birds of White Sea-Baltic direction of migration with Leucocytozoon takes place in general in nesting places. It should be noted that settled birds do not reflect quite correctly the infection pattern with blood Protozoa in the region in question. That is why conclusions concerning a role of migrations in the infection of birds with blood parasites, which rest only upon the difference in infection extensiveness of settled and migratory birds, are not quite reliable.

Sucking lice collected from two species of birch mice of the subfamily Sminthinae were studied. Sicista betulina Pallas from Komi ASSR is parasitized by Schizophthirus sicistae Blagov. described from S. subtilis Pallas from the Altai Territory and found on the same host in the Ukraine. Sicista tianschanica Salejisky, the distribution area of which is limited by Tien-Shan, is of parasitized by Schizophthirus singularis Sosnina sp. n. which differs by the presence of one (instead two) large spinelike seta on the hind edges of two sternal plates of 2nd abdominal segment and by some other characters.

The lack of repeated bloodsucking does not affect essentially the infection of Ae. aegypti mosquitoes with malaria agent, P. gallinaceum.

Two species of ixodids, Ixodes arboricola Schulze et Schlottke and I. frontalis (Panzer), new for the fauna of Armenia are given. Larvae and nymphs of these ticks were found on birds in the forest zone and gardens.

Summary is absent.