Архив выпусков

In studyig exponent k of the negative binomial distribution, employed for modeling the distribution of cattle grubs in the herds of cattle, its values were found to increase with increasing incidence of infestation. This correlation is due to a more intensive effect of factors limiting the number of warble-flies with increasing density of their populations. According to equation of regression: Y=4.517—0.0436 X, where Y=1/k, X — per cent of infested animals in herd, the model was computed showing changes in the number of Hypoderma bovis larvae with changing incidence of infestation. The range of application of such models is discussed.

Heteromorphic deutonymphs, or hypopi, are known only in the Acaridiae (Sarcoptiformes). In all the species where the life-cycle is known, the corresponding adults belong to free-living mites, even in the group where the hypopi are subcutaneous parasites of birds. Six different major types of hypopi may be distinguished: 1) The "Acarid" type: there is an attaching organ, consisting of a suctorial plate, on the ventral surface of the opisthosoma. Legs normal, ending in claws, at least for the first legs. 2) The "Anoetid" type: these hypopi differ from the former mainly by the structure of the legs are strongly modified. 3) The "Labidophorus" type: the sucking-plate is replaced by an apparatus consisting of two pairs of claspers and one pair of movable flaps and that is able to clinging to the hair of a mammal. 4) The "Rodentopus" type: there are no attaching organs on the idiosoma but tibiae III and IV bear specialized, strongly modified hairs that probably serve for the fixation on the hair of a mammal and also to move along it. All these hypopi live completely embedded in the pilous follicles of mammals, almost exclusively rodents. 5) The "Echimyopus" type: these hypopi differ from those of the "Rodentopus" type by the strong modification of the legs and the complete absence of the anus. They live in the pilous follicles of south-american rodents. 6) The "Hypodectes" type: idiosoma and legs without attaching organs. The legs are normal in structure and they have no claws. Palposoma (=gnathosoma) vestigial. These hypopi are parasitic under the skin of birds, mainly pigeons. One species is living under the skin of an African rat. All these hypopi belong to the family Hypoderidae Murray, 1877 (syn. Hypodectidae Fain and Bafort, 1966). The life-cycle is known for one species of this group, Hypodectes (Hypodectoides) propus (Nitzsch). It has been worked out by Fain and Bafort (1966—1967). The hypopi of this species live under the skin of domestic and wild pigeons in various part of the world. The adults live free in the nests of these birds. The life-cycle is strongly shortened. The female lays eggs which transform directly into hypopi. These, very small, hypopi invade the young birds living in the nest. In the tissues of the bird these hypopi grow by absorbing food by osmosis. When they are completely developed the hypopi leave the bird, drop in the nest and transform directly into adults, male and female.

A new species, Listrophorus brevipes sp. n. was found on rodents of the genera Microtus and Clethrionomys. Adults of the new species are described in detail. L. brevipes is related to L. leuckarti but differs from the latter in having a greater number of parietal tubercles along lateral striae. Females of both species differ in having various patterns of striation on the dorsal side of hysterosoma (fig. 1). In males of L. brevipes legs IV are short, not reaching the posterior edge of opisthosomal lobes. In L. leuckarti they always extend backwards beyond the border of the body. The shape and position of dorsal hysterosomal shields and pattern of striation around them are also characters of the species (fig. 7).

Permanent ectoparasites begin to migrate from females to their young when the latter are 6—7-day-old and covered with short hair. On young of all broods there were found parasitic arthropods living in nest and larvae of ixodid ticks. Ixodid larvae were more abundant on bare sucklings (2—3-day-old). Nest parasites were more abundant on young covered with short hair (6—7-day-old). Endoparasites are absent in sucklings.

In the forest zone of East-European plain (the Polesje Province), in the Volyn and Brjansk regions 874 ticks of Ixodes apronophorus P. Sch. were collected from small mammals (14 species) and nest litter of water voles. In all, 683 larvae, 94 nymphs, 89 females and 8 males were collected. Arvicola terrestris L. (index of abundance — 2, occurrence — 41%), Sorex araneus L. (index of abundance — 1.04, occurrence — 45%) and Clethrionomys glareolus Schreb. (index of abundance — 0.7, occurrence — 33%) from older biocoenoses were infested most of all. The ticks should be collected in spring when nymphs and adults are especially active.

Comparative studies of Dermacentor marginatus Sulz. and Ixodes ricinus L. have shown that the causative agent of tularemia is less adapted to I. ricinus, especially to its adult phase. They make themselves free from Francisella tularensis more often and therefore more seldom than D. marginatus transmit the agent to susceptible animals. I. ricinus parasitizes not only mammals susceptible to tularemia but also birds and reptiles little or nonsusceptible to this infection. Since in nature birds and reptiles are not involved in the agent circulation, the infection of the ticks of this species occurs more seldom.

The effect of 14 repellents on adults from natural populations of Ixodes persulcatus and Dermacentor pictus was studied under laboratory conditions. Ribbons of cotton fabric were treated with repellents at a rate of 10—20—40 g of active ingredient per m². The distance covered by the ticks was taken into account, the route being figured. Butylacetanilide diethyltoluamid, acetyl tetrahydrochinoline, M-1960, carboxide (20—40 g of a. i. per m²) showed the greatest repellent effect on both species. As regards D. pictus isoamylacetanilide and isopropylacetanilide were also efficient. The adaptation of ticks to repellents should be noted. With the second exposure to repellents the reactivity of ticks diminished. Dimethyl-phthalate, benzoyl piperidine and dibutyl adipinat produced the most weak effect.

Studies were made on the changes in longevity of fleas of the great gerbil, depending on temperature and humidity of the medium and the habit of feeding on the host. It was established that 75—91% air humidity was optimal for Xenopsylla gerbilli minax. At 7—8°, periodical feeding and optimal humidity fleas lived 197 days (maximum life duration). Higher temperatures caused the shortening of the life of insects. At 17—20°, 23—27° and 30° fleas lived 150, 140 and 99 days, respectively. Fleas, which were fed periodically, had maximum duration of life. Unfed fleas died most quickly. When living on the host, females intensively led eggs that caused the senescence and death of insects.

137 bird nests were examined in the south of Turkmenia and Uzbekistan. In 24 nests midges of the genus Leptoconops were found, sometimes in great numbers. Midges were also collected from adult birds (from 55 out of 1995 birds obtained). The midges collected belong to the following species of the subgenus Leptoconops: L. lucidus Guts., L. bidentatus Guts. and L. bezzii Noe. L. lucidus was recorded as being dominant.

The blood from intestines of some species of sand flies was investigated by means of the precipitation reaction in agar to determine their epidemiological role. Sand flies were caught in nidi of visceral leishmaniasis in South-East Turkmenia from colonies of the great gerbil and living accomodations. It was established that Phlebotomus grimmi, Ph. papatasi and Ph. chinensis suck blood of most accessible animals, while Ph. chinensis tends to suck blood of man that is of certain epidemiological significance.

The paper deals with a new species — Prosimulium multicaulis sp. nov. from Lower Priamurje. The new species has some differences from the allied species P. alpestre Dor. et Rubtz.

As a result of helminthological studies of Gaidropsarus mediterraneus (L.) the number of species of helminths recorded from this fish increased from 11 to 24.

The paper contains descriptions, differential diagnoses and figures of Idiogenes skrjabini sp. nov. (from Otis tarda, Mongolian People's Republic) and Raillietina (Raillietina) gvosdevi sp. nov. (from Streptopelia turdur, Kazakh SSR).

The paper deals with two new species of nematodes from North Viet-Nam: 1. Tetrameres (T.) vietnamensis sp. nov., found in the muscular stomach and proventriculus of Lophura nycthemera (Galliformes), 2. Oxyspirura thanhhoaensis sp. nov., found in the conjunctival sac of Garrulax leucolophus and Myophonus coeruleus (Passeriformes).

Invasional larvae of Aschworthius sidemi, Oesophagostomum radiatum and O. venulosum were studied. The distinguishing features were the lenght of larvae, size of the tail and structure of the intestine. During the coprological examination of 3-4 month-old calves the eggs of A. sidemi were found. It was established that the life cycle of A. sidemi is 2 months. The tests on the influence of frost upon the viability of helminths have shown that dangerous are only eggs laid from April, i. e. when frosts are of short duration.

A new nematode Skrjabinobronema pileati sp. nov. (Schistorophidae Skrjabin, 1941) from the muscular stomach of Halcyon pileata from the Rimsky-Korsakov Islands (the Bay of Peter the Great) is described.

Studies were made on the infestation of the alimentary canal of man with parasitic Protozoa and their age distribution. The work was done in the northern and southern regions of the Soviet Union and in Leningrad. It was established that Trichomanas hominis, Chilomastix mesnili and Enteromonas hominis occur more seldom in the North (Jakutia, Leningrad) than in the south (Ukraine, Azerbaijan, Turkmenia). Infestation with T. hominis, T. elongata, (=T. tenax) and C. mesnili increases with age. on the other hand, infestation with Lamblia intestinalis decreases with age and is the highest in joun-ger age groups (to 5 years). Infestation with E. hominis does not undergo considerable changes.

After the infestation with sporozoites or merozoites Eimeria tenella develops on chicken embryos and completes its endogenic life cycle. Oocysts obtained from chorioallantois and alantois fluid normally sporulate and cause the infestation of chickens. Sporozoites of E. tenella introduced into the cells of tissue cultures of chicken fibroblasts and kidneys of chicken embryos develop to schizonts of the second generation.