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Experimental infection of Hyalomma plumbeum Panz., Rhipicephalus rossicus Jak. et K. Jak. and Dermacentor marginatus Sulz. with the virus of the Crimean hemorrhagic fever has shown that preimaginal phases of the above ticks easily receive an infection agent from the infected donor, preserve it for a long time, transmit it through a bite during feeding to susceptible animals; during metamorphosis they transmit this agent to the subsequent developmental phases as well as to the progeny of infected individuals from one generation to another.

A description and figures of four new species are given: Sternostoma strigitis sp. n. and Rhinoecius brikinboricus sp. n. from Asio otus (L.), Rhinoecius alifanovi sp. n. from Asio flammeus (Pontopp.) and Rhinoecius nycteae sp. n. from Nyctea scandiaca (L.).

Observations on the swarming of mosquitoes were conducted in the flood plain forest of South Yamal (67° N. L.). The individuals of Aedes communis made 83 to 94% of the swarming males. Their number in swarms varied from 30 to 800 specimens. The dynamics of the swarming males number depends on the rate of their emergence from the pupae. At the mass emergence the number of swarming males was 3 times higher though the increase in the general size of the population was negligible. Synchronization of the swarming time of males was also favoured by warm windless weather.

Studies were conducted of the effect of temperature and humidity, variant of plague microbe, frequency and duration of feeding and specificity of the host on the blockformation in the souslik fleas C. tesquorum and N. setosa infected with plague. 28 tests on the effect of temperature and humidity on the blockformation were undertaken, for which 14411 fleas of the above species were used. A temperature of 16 to 22° proved to be optimal; at this temperature the number of blocked fleas (C. tesquorum) varied from 21.2 to 42.7% and that of N. setosa — from 41.9 to 54.2%. Marmot variant of plague microbe caused the formation of the "block" in 53.3 to 55.1% of fleas of N. setosa in 3—4 days and in 28.0 to 42.7% of C. tesquorum in 10—14 days after the infection. In C. tesquorum the process of blockformation is affected by the frequency of feeding, in N. setosa — by the duration of each feeding.

The time required for the development and survival rate of preimaginal phases of C. wladimiri were studied. Experiments were conducted at a temperature from 0° to 30° C and relative air humidity from 60 to 100%. Temperatures between 18° and 30° C and humidity between 90 and 100% are most favourable for the complete developmental cycle of these insects; imagos hatched under these conditions accounted for 9 to 46% of eggs used in experiments.

The helminthological investigations were conducted from May 6 to May 28, 1972 in the Karaginsk Gulf of the Bering Sea. The helminths were collected from 124 specimens of Phoca vitulina largha, 9 specimens of Erignathus barbatus nauticus, 9 specimens of Pusa hispida krascheninnikovi and 9 specimens of Histriophoca fasciata. In all, 23 species, 2 immature and 1 larval form of helminths were recorded. The data are given on the localization of helminths, intensity and extensity of their invasion, pathogenic effect on the host. The age dynamics of the helminths from Phoca vitulina largha was studied. For the first time are reported the trematode Orthosplanchnus pygmaeus, the cestode Diplogonoporus tetrapterus and nematodes Anisakis simplex, Anisakis sp. and Parafilaroides krascheninnikovi in Phoca vitulina largha and the nematodes Anisakis sp. and Phocascaris cystophorae in Pusa hispida krascheninnikovi.

Trematodes, parasites of H. ulvae, do not affect the adaptation of the host to moderate changes in salinity from 25 to 10-14‰. At the same time the resistance of infected molluscs to fresh water decreases.

Hystological studies of glandular formations in 16 species of cercariae were carried out. Their secretion was found to contain acid and neutral mucopolysaccharides, mucins, mucoproteins and elastin. The classification of types of glands is specified. The glands can be of the following types: cystogenic, case forming, mucoid and glands of penetration. The glands performing uncertain functions and caudal ones are separated into a special group. On the basis of obtained data on the uniformity of chemical compounds of the secretion of glands belonging to different groups their common origin has been suggested. It has been shown that the main trends of the evolution of glandular formations in cercariae depends on the evolution of the life cycle of trematodes.

The paper deals with the specific composition of the genus Diplostomum, parasitic in fishes and Cyclostomata of the USSR. A key is given for the identification of 13 species of the genus. Each species is provided with a brief morphological characteristic including main taxonomic characters of the species.

There are some variations in the dimensions of anchors depending on the age of the host, localisation and number of parasites. To differentiate such close morphological species as D. vastator and D. crassus it has been suggested to take into account, in addition to taxonomic features, the correlation between the anchor ventroapical length and the bend.

6 new species of the genus Neohaliotrema Yamaguti, 1965 are described and a new genus and species, Paraneohaliotrema microspathodoni Zhukov gen. et sp. n., (Monogenoidea, Polyonchoinea) from the fishes of the family Pomacentridae from the of Gulf Mexico are erected. The specimens described were found in Abudefduf saxatilis, A. taurus and Microspathodon chrysurus caught in the Habana region. The interrelationships between investigated hosts and their parasites are discussed. The Indo-Westpacific origin of the genus Neohaliotrema has been established.

On the territory of the Karakalpak ASSR the infection of sand flies Phlebotomies papatasi, Ph. caucasicus, Ph. andrejevi and Ph. mongolensis with the agent Leishmania tropica major ammounts, on the average, to 39.3%. The virulence of 88 investigated strains of Leishmania for white mice estimated by their infection and the duration of incubation was found to be different: one half of the strains had high, one third — average, and the other strains — low virulence.

In Lake Itkul situated north-westwards of the town of Abakan there were found encysted metacercariae of Apatemon annuligerum in the eyes of the perch. Adult fishes are 100% infected, the infection intensity amounting to 28 to 455 cysts (125 on the average). Maximum infection of the perch takes place at the age of 4 to 5 years. In elder fishes proceeds a decrease of infection intensity on account of a considerable mortality of cysts. There was undertaken an infection of incubative ducklings and observed a development of marita to a mature state. The maturation of eggs takes place on the 5-th day.

Under conditions prevailing in the Leningrad region Ixodes lividus has, in general, a one year life cycle. Having engorged on swallows overwintering larvae come off in burrows and in 24—26 days moult for nymphs. In a fortnight after 4—5 day feeding on nestlings the latter transform into imagos. After passing the stages of the postmoulting development (3—4 days), feeding on nestlings (5—7 days), rest (7—8 days) and oviposition (14—18 days) the females die. Larvae of a new generation appear in August—September. However, 2.8 to 6.5% of individuals in a population, due to late feeding of larvae or mortality of hosts, stop in their development at phases of imago and nymph and hibernate together with larvae. In an overwintering population they accounted for 3.4—5.0%.

The occurrence of the earlier unknown species Culiseta longiareolata in Middle Povolzhje is reported.

In water bodies of the flood-plains of the Hi and Turgen rivers (Alma-Ata district) there were found larvae of Tabanus autumnalis infected with the fungus Metarrhizium anisopliae. Experiments on the infection of T. autumnalis with this fungus yielded 100% mortality of larvae and adult insects. The possibility of creation of an artificial infection nidus under natural conditions was established.

Larvae of Aedes aegypti were found to be infected both by Lankesteria culicis and Tetrahymena stegomyiae, the infection rate accounting for 33%. The infected larvae are from two to three weeks behind in their development from uninfected ones and die.

Summary is absent.

Summary is absent.