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The attacking activity of unfed nymphs of Ixodes ricinus and its dependence on preceded photoperiodic conditions were investigated. Aggressiveness of long-day nymphs is 3—10 times greater than that of short-day nymphs. The low attacking activity of short-day nymphs is explained to be a result of behavioural diapause. The transfer of short-day nymphs into long-day regime causes the elimination of diapause state and stimulates their activity. The same effect is caused by an increase in temperature (from 18 to 25°). The transfer of long-day nymphs into short-day regime does not influence the active state acquired before, that demonstrates the non-reversibility of the state. The reactions to photoperiods and their changes are similar in both preimaginal phases of I. ricinus but differ from those in adults of Dermacentor marginatus where the repeated induction of behavioural diapause is possible.

On the basis of experimental data the author denies the salivary-oral mechanism and transovarial transmission of tularemia microbe in the mite Ornithonyssus bacoti Hirst. The transmission of infection to animals proceeds by alimentary way or by swallowing mites or by their crushing on the skin of the host. The reproduction of tularemia! bacteria proceeds in infected mites during their metamorphosis.

It was experimentally found that during feeding on white mice Xenopsylla cheopis were capable of being infected with Salmonella enteritidis. However, under conditions of constant access to the host ectoparasites get free grom infection very readily. We succeeded in observing the transmission of infection via fleas only in those cases when insects were placed on sound mice in mass and not later than 24 hours after infectious feeding. Salmonella exerted a pathogenic influence on fleas expressed in the shortening of their life.

Extract obtained from midgut content of I-st instar larvae of Hypoderma bovis De Geer contains homogenous protein substance, protease. This substance is more active in relation to haemoglobin as compared with other proteins tested (albumin, collagen). Being very toxic protein affects mainly the central nervous system. The effect of toxin is not prevented by introduction of antihistamine and cholinesterase substances. The intensity of toxicity in each particular case depends apparently on the amount of substance entering the blood channel.

The paper contains new data on the occurrence and bionomy of cattle warble flies (Diptera, Hypodermatidae) in the Mongolian People's Republic. The degree of infestation, ecological factors and seasonal dynamics as well as the distribution and species composition of the warble flies were studied in the main pasture regions. The southern boundary line of distribution of the predominant species Hypoderma bovis was found to coincide with the geobotanical line of the steppe and semi-desert zones.

The paper describes two new species with colourless wings, Culicoides sensillatus sp. n. and C. sajanicus sp. n., and male of C. variifrons Gluch. et Ivan. A description of morphological characters and brief information on the biology of little-known species, C. gutsevichi Sen. et Das Gupta, C. lenae Glust. et Mirz., from Siberia are given.

In studying karyology of natural populations of Schönbaueria pusilla Fries and Sch. gigantea Rubz. there were discovered a peculiar morphology of polytene chromosomes of these species and significant differences in their karyotypes. The presence of all developmental phases of the species, the original, but incomplete description of which was made from 1♂ and 1♀, enabled us to raise a question of the true position of this species in the system of the family and to find out that Sch. gigantea in morphological characters differs from all known species of the genus Schönbaueria End. There was observed a similarity in the structure of all developmental phases of Sch. gigantea Rubz. to Peruvian species of the genus Hemicnetha End. and erected a new taxon for Sch. gigantea (Rubz.).

When infected with Dactylogyrus vastator Nybelin, 1924 the hybrid carp from Ropsha ponds develops a relative super- and postinvasional immunity of general action which can preserve under optimal conditions more than two months. The immunity depends on the intensity of infection, temperature conditions and species of fishes. The increase in immunological resistance of infected fishes is a result of activisation of their protective mechanisms — complement, properdin, phagocytic reaction and specific antibody formation. Immunisation of fishes with depositing antigene from D. vastator increases to a rather high extent their resistence to infection.

The author gives a redescription of Engraulicola thrissocles (Trip., 1959) comb. n. and considers the limits and systematic position of the group of amphipolycotylous monogeneans. In the subfamily Gastrocotylinae Spr., 1946 the group in question is recognized as a distinct tribe, Amphipolycotylini trib. nov., together with four other new tribes, Gastrocotylini; Pseudodiclidophorini, Priceini and Cypselurobranchitrematini. The author suggests a new system of classification of the subfamily Gastrocotylinae Sproston, 1946 (13 genera, 27 species), gives diagnoses of the separated taxons and makes taxonomic remarks.

Metacercariae of Tetracotyle sogdiana were found repeatedly in the body cavity of members of Schizothorax genus from the south of Kazakhstan and Middle Asia. Mature form remained unknown. We succeeded in obtaining marita experimentally from the intestine of Buteo rufinus. The paper contains a description and figures of metacercariae and marita. The latter turned to be a new species, Apharyngostrigea sogdiana sp. n.

In small intestines of sheep and goats we found 39 specimens of Moniezia. They much differed from all known species of the genus Moniezia Blanchard, 1891. They were determined as a new species of Moniezia (Blanchariezia) skrjabini sp. n. A description of this species and the differential diagnosis are given.

The paper describes a new species of cestodes, Amoebotaenia oophorae sp. n., from the intestine of Pluvialis apricaria (L.) from the coast of the White Sea. In A. oophorae proglottids with the developing uterus get detached from the strobila. The oophore develops inside the uterus enveloping as a case all eggs of the proglottids. On the anterior edge of the proglottids the opening is formed through which the oophore goes out.

Five species of nematodes of the genus Acuaria were found in Passeriformes from the Kurish spit. The species Acuaria tenuis (Duj., 1845), A. muscicapae (Linst., 1878), A. papillifera (Linst., 1878), A. dollfusi Chab. et Pett., 1861 and A. paragalliardi Chab. et Pett., 1961 are reduced to synonyms of Acuaria attenuata (Rud., 1819). The first description of the female of Acuaria brumpti Chab. et Pett., 1861 and variations in sizes of Acuaria subula (Duj., 1845) are given.

The ability of larvae of helminths, which reach the invasional state in intermediate hosts, to passage into reservoir hosts can be used for their artificial accumulation and maintenance in order to utilize them in experiments for other purposes. Reptiles can be used as artificial accumulators since their maintenance requires minimum expenditures of labour and time.

It is reported herein on the occurrence of Acanthobdella peledina in the upper reaches of the Lena river and the basin of Lake Baikal. The geographic range of the species is restricted to two regions: Kola-Feno-Scandinavian and European-Siberian. The latter is enclosed by the borders of the recent distribution area of permafrost while the former lies in the area of formation of Pleistocene continental ice. In the European-Siberian distribution range of the ancient leeches there is an isolated southern part — water bodies of the North-Baikal and Stanovoj elevations —which is limited by the distribution area of Pleistocene glaciers.

In waters of the Mari ASSR larvae of Aedes communis DeG. were found to be infected with the microsporidia Thelohania opacita Kudo, which become localized in the fat body and haemolymph of the host. In nature from 4 to 18 per cent of larvae are infected. 98 to 100 per cent of larvae selected according to external features (white spots on segments of the abdomen) die. The microsporidia in question are a geographic variety of Thelohania opacita Kudo. The size of spores is 6.05—7.26X4.2—4.8 mk. In their morphology they resemble spores of Thelohania californica Kellen et Lipa.

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Summary is absent.

Summary is absent.