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Summary is absent.

Recent evidence on the life cycles of the toxoplasmids (Toxoplasma, Besnoitia, Sarcocystis, Hammondia, Frenkelia) has been analysed. The availability of the complex life cycles, including the alternation of sexual and asexual reproduction, in addition to gametogenesis involving the independent development of gametes that produce unequal numbers of gametes, makes it possible to include the toxoplasmids into the family Eimeriidae within the order Coccidiida. A detailed evidence recently provided for Isospora has suggested a kinship of this typical coccidian genus with toxoplasmids. At the same time much similarity is obvious between Isospora and Eimeria in the general pattern of their life cycles. Hence, the family Eimeriidae is suggested to be divided into two subfamilies: Eimeriinae Wenyon, 1926 with Eimeria as the type genus and Isosporinae Wenyon, 1926 with Isospora, Toxoplasma, Besnoitia, Sarcocystis, Frenkelia and Hammondia. The main features of the former subfamily are: various oocyst structures, the lack of the extra—intestinal development obligatory monoxeny. The main characters of the latter subfamily: oocysts of the same pattern, the involvement of extra—intestinal development, shifts from facultative to obligatory heteroxeny.

Ultrasonics (frequency — 20 kHz, intensity — 11.9 w/cm² and external lateral surface — 1.88 cm²) can annihilate for 8 minutes from 90 to 100% of non-sporulated and for 16 minutes 99.5 to 100% of sporulated oocysts of E. tenella maintained in 10 ml suspension plunged into a bath with ice. The destruction rate of oocysts depends on the duration of the ultrasonics effect and the increase of its intensity. It should be noted that the increase in intensity is more effective in this respect than the extension of ultrasonics effect.

It is expedient to use the scanning electron microscopy for studies of parasitic Protozoa of fishes. The structure of myxosporidians (Henneguya psorospermica, Myxidium rhodei, Chloromyxum truttae) and Chilodonella cyprini was analysed. Microphotos taken by «CWIKscan-100-4» are given. The technique of the preparation of the object for scanning microscopy with regard for its structure is discussed.

The transovarial transmission of C. burneti by the tick H. asiaticum was traced on three daughter generations during 751 days. The infection rate of the first generation ticks was found to be 5 times lower than that of the parental ones, of the second generations ticks — 9 times lower while F₃ population was characterized by 20 fold decrease in the infection rate. The transmission of C. burneti by the infected males of H. asiaticum to the females after copulation was observed in none of the 19 tests. Analysis of the material obtained has shown that the unrestrictedly long "vertical type" maintenance of the Q-rickettsiosis agent in nature is impossible.

From tissues of E. pancreaticum were isolated mitochondria capable to swell under the effect of some factors. The intensive oxidation of succinate, isocitrate, cisaconitate, oxalacetate and α-ketoglutarate by mitochondria and less intensive one of malate, fumarate, citrate and pyruvate were shown. NAD caused the rise in oxidation intensity of isocitrate, cis-aconitate, oxalacetate, α-ketoglutarate, malate, fumarate and pyruvate while NADP — of isocitrate and citrate.

Four new species of trematodes are described from fishes of the Falkland-Patagonian region as follows: Infundibulostomum patagonicum from Notothenia ramzay; Stenacron mancopsetti from Mancopsetta maculata; Neolepidapedon argentinensis from Salilota australis; Hirudinelloides elongatus from Thyrsites atun. For the latter species a new genus, Hirudinelloides, has been erected. Representatives of the genera Infundibulostomum, Stenacron and Neolepidapedon are first reported from this region.

The nematodes of C. cirratus of stages III, IV and V were found in the gut of cod Gadus morhua and navaga Eleginus navaga from the White Sea. The morphological data on 176 specimens of C. cirratus were subjected to statistical analysis. The developmental stages can be distinguished by means of measurements of the width and length of pseudobuccal cavity. The first description of stage IV of C. cirratus and detailed redescription of the IIId stage larvae of С. cirratus are given.

One male of Cephalobellus sp. from the hind-gut of Levisonus thaum is described from the Shkotovsky region of the Primorje territory. It has endokupol, a complex of cephalic structures formed by the inner cuticular layer of the cephalic end. The stomatoidal ring of the endokupol is fixed to stomatorhabdia supporting the stoma. The comparison of endokupols of Cephalobellus sp. and those of marine nematodes shows their homology; an opinion is expressed on the independent (parallel) origin of endokupol of Cephalobellus sp.

Collections from rodents conducted over a period of 11 years in natural nidi of tularemia in the Leningrad region include the ticks of Ixodes persulcatus, I. ricinus, I. trianguliceps and I. apronophorus. The redbacked vole is the main host of I. trianguliceps larvae. The larvae of this species have two peaks of abundance, in June and September. Larvae and other developmental phases of I. apronophorus were most abundant on water vole in June. Larvae of I. persulcatus and I. ricinus feed on small mammals in general but the latter are unessential in the feeding of nymphs.

During the swarming period of black flies aggregations of the mass species Schönbaueria pusilla Fries and Simulium truncatum Lundstr. (Jakutia), Byssodon maculata Mg. and S. longipalpe Belt. (Tomsk and Novosibirsk regions, Lower Priamurje) were noted. Observations on the time and character of swarming, statial distribution of swarming black flies and on weather conditions were conducted.

The paper presents results of investigations of fleas from Citellus pygmaeus obtained during epizootological surveys in 1972—1974 (the Ergenin ridge, Kalmyk ASSR). The most high number of the main species of fleas of C. pygmaeus was observed in the first year of epizootic on the background of great abundance of the host (over 30 specimens per 1 hectare). In the following years the decrease in the number of C. pygmaeus was accompanied by the fall in the fleas number. The distribution of different species of fleas in a microbiotope is uneven in various periods. In all periods in nests fleas of Neopsylla setosa were dominant while fleas of Ceratophyllus tesquorum were most abundant on the host. In burrows there was rioted a change of dominant species: in the period of intensive epizootic of 1972 they were Ctenophthalmus pollex and Ceratophyllus tesquorum, in 1973 during a slump of epizootic — C. tesquorum and N. setosa and in 1974 when epizootic was not discovered at all — N. setosa.

Two new species of the genus Scyphidia are described. The species were collected in 1964—1966 on fishes from waters of the Kolkhida-Anatolijsky area. S. baninae was found on the skin of Alosa caspia palaeostomi and S. doliaris — on the skin of Cyprinus carpio.

Data are given on the structure of eggs and larvae of Diplozoon megan from the gills of the ide. The occurrence of local stock of these fishes in the Kurish Gulf is suggested.

Encysted metacercariae of Microphallus sp. were found in the land mollusks Bradybaena duplocincta and Jaminia potaniniana asiatica collected on the slopes of Tien-Shan. The above mollusks are first reported as intermediate hosts of microphallids. The metacercariae found were fed to white mice, golden hamsters, chickens and nestlings of sparrows and starlings. Maritae developed only in white mice and golden hamsters. Mature trematodes containing 14 to 35 eggs in the uterus were found in the small intestine 66-90 hours after the infection. Small mammals are assumed to be the definitive hosts of these trematodes. The trematodes of Microphallus sp. are characterized by a short life cycle with one intermediate host, land mollusk.

At the invasional larva stage all the species of Trichinella display different variations in the characters by which the sex can be identified. They should be taken into account in identifying trichinellids by crossing.

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Summary is absent.

Summary is absent.

Summary is absent.