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The effect of superphosphate, nitrophoska and ammophos on larvae of Culicidae was studied under laboratory and field conditions of the Novgorod region. Superphosphate better than other fertilizers acidifies water, while nitrophoska and ammophos increase the ammoniac contents of 27 to 240 fold that affects lethally the larvae. 0.4—0.5% and 1% concentrations of mineral fertilizers are a lethal dose for I—II instar and III—IV instar larvae, respectively.

In hungry larvae of E. rotundata paired simple alveolar salivary glands (greater, anterior-medial, dorsolateral I and II) have a different ultrastructure of cells and secretory inclusions and after hatching undergo a process connected with their final differentiation that determines the postlarval completion of development of larvae. Passages of glandular ducts are identical to those of postlarval phases, greater and anterior-medial larval glands are homologous to ventral and medial glands' of hymphs and adult ticks respectively, and dorsolateral I and II glands to dorsal and lateral glands of the latter. Therefore, different adaptation mechanisms of individual phases of the life cycle, the secondary parasitism of larvae in particular, are realized on a single anatomical basis of salivary gland complex.

The part of birds of Kurish populations infected with Haemosporidia of southern origin is determined. On the basis of actual material and literary data the role of seasonal migrations of Palaearctic migrants to various zoogeographical regions for infection with Haemosporidia and further fate of Protozoa of southern (northern) origin in nesting (wintering) distribution areas of birds are discussed.

Monthly studies on the seasonal parasite fauna dynamics of pike, minnow and perch were carried out from May, 1974 to September, 1977. It was found out that the myxosporidian Henneguya creplini has a one-year life cycle. The infection of perch with this parasite takes place at a water temperature not exceeding 13°. In other species (Chloromyxum esocinum, Ch. mitenevi, Myxobolus cybinae) the life cycle is shorter, in consequence of which fishes can be infected with these parasites several times a year and in different seasons. The nature of seasonal changes in abundance of myxosporidians depends to a great extent on weather conditions of each concrete year.

The data demonstrating the presence of the glucose active transport system in the cestode T. nodulosus are obtained. Kinetic characteristics of the transport are estimated and their dependence on the incubation temperature are shown. Heterogeneity of the worm body in respect to transport processes and their dependence on the physiological state of cestodes are discovered. The absorption of different forms of glucose is studied and the similarity of digestion processes in parasites and their hosts is shown.

The fine structure of the excretory bladder in three species of trematodes of bats (Myotis brandtii, M. dasycneme) was studied. Prosthodendrium ascidia and P. mirabite (the family Lecithodendriidae) have almost the same ultrastructure of excretory bladder epithelium but they differ in this respect from A. amphoraeformis, a member of the family Allassogonoporidae. The characteristic features of P. ascidia and P. mirabile are long lamellae arranged in parallel rows lying along the surface of syncytium and great quantity of lipid granules, which are obviously excreted. Excretory bladder epithelium of A. amphoraeformis does not contain any significant amount of lipids and its apical membrane has rather short projections. Its syncytial layer consists of zones with different fine structure. Those of them which are thin, covered with microvilli and containing intracellular canals are apparently involved in the reabsorption, while thick parts of the epithelium, full of vacuoles, in the excretion. Differences in the fine structure of the excretory bladder epithelium of two species of Prosthodendrium and A. amphoraeformis can be regarded as a confirmation of Odening's point of view, who separated the families Lecithodendriidae and Allassogonoporidae according to the form of their excretory bladder.

The biology of the trematode Echinochasmus milvi Yamaguti, 1939 under the conditions of the southern Far East of the USSR is studied. The development of the trematode proceeds with the participation of intermediate hosts, molluscs of the genus Juga, additional hosts, freshwater fishes, and definitive hosts, fish-eating birds and mammals, and is completed at a temperature of 17 to 23°, within 21 weeks.

The formation of parasite fauna of fishes from water reservoirs of the Daugava differs from that of plain type water reservoirs of the moderate zone. Instead of expected flourishing of limnophilous elements an intense, increasing with years impoverishment of the specific composition of nearly all systematic groups of fish parasites is observed in the studied reservoirs. The impoverishment of the parasite fauna in the water reservoirs is associated first of all with their relatively small sizes, frequent and strong fluctuations of the water level and repeated dryings of large bottom areas. The investigations show that such a picture of fish parasite fauna genesis is observed in all relatively small water reservoirs with frequent and strong fluctuations of water level.

During last few years a tendency for the reduction in the number of parasites of all investigated fishes has been observed. This is connected with the general tendency for the impoverishment of the reservoir flora and fauna, that may be the result of the fluctuations of its water level. Finally this process leads to the reduction in the number of many species of parasites and even to their disappearance.

Pellucidhaptor fidus sp. n. from gills of the lake minnow (Phoxinus percnurus) from the Anadyr river basin is described. It differs from the majority of other members of this genus by the structure of the distal part of copulatory tube and from P. merus (Zaika, 1961) by the structure of anchors. The minnows parasite fauna consists of 8 species, of which 6 species were found in the rivers of Chukotka for the first time. The finds of Phoxinus percnurus in water bodies of the Markov hollow, the finds of Pellucidhaptor fidus and Cleidodiscus brachus point to the connections between the Asian and American faunas of Leuciscinae and to a greater variety of the boreal-plane fauna in Chukotka water bodies in Oligocene — Pliocene time.

By differential centrifugation method a lysosomal fraction was obtained from five species of cestodes, which possesses the highest specific activity of acidic phosphatases as compared to other subcellular fractions. By isopyknic centrifugation in the density gradient of saccharose the lysosomal fraction is divided into primary and secondary lusosomes. Lysosomes of cestodes are similar to those of vertebrate animals in the character of fractional distribution of acidic phosphatase, sedimentation abilities and sensitivity of membranes to triton X-100.

The lipid content of Paramermis tabanivora parasitic in tabanid larvae was investigated by the method of gas-liquid and thin-layer chromatography. It has been established that the main lipids in this nematode are triacylglycerines and, to a lesser extent, phospholipids while the content of free and etherified cholesterol is relatively low. Fatty acid conten of mermithids is charactearized by a high degree of nonsaturation. There are differences in the fatty acid content of triacylglycerines and phospholipids. Membrane lipids of mermithids contain more polyene acids (С20 : 3, C20 : 5).

Investigations carried out in the Pavlodar District have shown that 7 species of ixodid ticks, Ixodes crenulatus, I. lividus, I. persulcatus, I. laguri laguri, Dermacentor marginatus, D. reticulatus, Haemaphysalis concinna, and one brought species, Hyalomma asiaticum, parasitize domestic animals and wild mammals. Maximum activity of pasture ticks of the genus Dermacentor falls on the end of April — beginning of May, that of H. concinna on the beginning of June. The growth in the abundance of pasture ticks, recorded during the last years, is favoured by the increase in the cattle live stock, its seasonal movements and pasture area reduction. Natural nidi of tularemia become more active. Since 1977 221 cultures of tularemia agent have been isolated from pasture ticks. H. concinna takes the most active part in the infection circulation.

Data are given on the relative abundance ratio of 3 species of ixodids obtained by different counting methods.

Parasitism of Lipoptena fortisetosa Maa on cattle was first established. Data on the distribution of this species in the USSR and its abundance on cows in Moldavia are given.

Summary is absent.

Summary is absent.