[Role of endoparasites of fleas of wild rodents in plague enzootia].

Laboratory studies of fleas for gregarines have established that it is the latter inhabiting the intestine and stomach of the fleas of wild rodents which are of much interest as protozoa, in whose organism, parasitic species of bacteria can survive. Penetration of plague bacteria into the endoplasm ofgregarines and their possible survival in the cysts may create an additional component in the chain of an epizootic process, which ensures its function, without involving the rodents at the nesting biocenotic level following the pattern: flea imagoes - nesting litter infected with gregarine spores, cysts - flea larvae - flea imagoes infected with cysts, with the plague pathogen emerging into a rodent population through the imago of blocked fleas.

[Current state of epidemiologic surveillance of natural foci of plague of North Caucasus]. / Sovremennoe sostoianie épidemiologicheskogo nadzora v prirodnykh ochagakh chumy Severnogo Kavkaza.

Information on the epizootic situation in plague in the natural foci of North Caucasus and on the influence of a number of anthropogenic and natural factors on this situation is presented. The data given in this work indicate that under the conditions of the anthropogenic transformation of landscapes the character of the epizootic manifestations of plague is changed and new factors, capable of aggravating epidemiological situation, appear. In addition, some other factors must be considered, such as the insufficient financing of reliable field surveys at present, the impossibility of making reliable epizootological studies due to causes of the social character (armed conflicts), thus making it impossible to evaluate, with a sufficient degree of reliability, the real epizootic state of a number of territories and, therefore, the risk of human infection. In this connection the necessity to carefully plan prophylactic measures and measures aimed at the localization and liquidation of the probable foci of infection arises.

[Principles of predicting the density of rodent flea populations]. / Printsip prognoza plotnosti populiatsii blokh gryzunov.

The paper gives the indices of abundance of fleas of different species of rodents in their fur and in their burrows and lays emphasis on the general mechanisms by which the density of these blood-sucking insects is a species-specific (populational) sign and does not greatly differ from the mean many-year values. By using Citellophylus tesquorum and other specias as an example, the authors present the results of a study of natural mortality in fleas, which suggest that the mean longevity of imagoes and death in the preimaginal phases of development are a hereditary sign. An example of calculation of the death ratio "K" in the imaginal phases is given and evidence is provided for compiling the signs of the density of fleas in taking individual samples of a field material and calculating the abundance indices of specific species.

[Specific features of the parasitic system of Crimean haemorrhagic fever in Stavropol' region during epidemic season of 2000]. / Osobennosti parazitarnoi sistemy krymskoi gemorragicheskoi likhoradki na territorii Stavropol'skogo kraia v épidsezon 2000 g.

Information on Crimean haemorrhagic fever (CHF) in different climatic zones of the Krasnodar territory is presented. The epidemiological importance of some species of Ixodes ticks as vectors of the causative agent of CHF was shown. Ticks Hyalomma marginatum proved to be the main vector species: they constituted 75-100% of all ticks collected from cattle, reaching the peak of their abundance in May. This species was found to be more aggressive than Dermacentor marginatus.

[Study of the natural sensitivity of Ixodes to insecticides]. / Izuchenie estestvennoi chuvsvitel'nosti iksodovykh kleshchei k nekotorym insektitsidam.

The article deals with the results obtained in the study of the natural sensitivity of the nature populations of Ixodes ticks to 4 insecticides. As revealed in this study, the ticks are highly sensitive to commercial preparations in different phases of their development. The selective sensitivity of different species of ticks to these preparations is noted.

[The results of a trial of the insecticidal activity of Oradelt and Omait against rodent fleas]. / Rezul'taty ispytaniia insektitsidnoi aktivnosti oradel'ta i omaita po otnosheniiu k blokham gryzunov.

The paper provides the results of examining the insecticidal activity of the commercial agents oradelt and omait against rodent fleas. The two agents have been ascertained to have a high toxicity for fleas of various species and genera. The field trials have shown that oradelt has a dusticidal effect in the habitats of mountain suslik. The oradelt dust containing 0.05% of the active ingredient should be recommended for controlling fleas in the foci of the suslik-type plague.

[Hemolymph cells of fleas and their phagocytic activity]. / Kletki gemolimfy blokh i ikh fagotsitarnaia aktivnost'.

The present paper concerns 4 groups of haemolymph cells of fleas (proleukocytes, leukocytes, trophic cells and oenocytoids), results of observations on their phagocytic activity during parenteral infection of insects with bacteria, bacilli, and cells' response to the infection with Microsporidia.

[Effect of nematoda Aphanitylenchus sp. on the reproductive capacity of fleas Ceratophyllus consimilis]. / Vliianie nematod Aphanitylenchus sp. na reproduktivnuiu sposobnost' blokh Ceratophyllus consimilis.

The paper presents results of experimental studies of the effect of Allantonematidae on the reproduction of fleas. It has been established that the pairing of non-infected females with males infected with nematodes reduces the fecundity rate while the pairing of non-infected males with females infected with nematodes causes a complete stopping of reproduction of laboratory population. The conclusion was drawn on the role of allantonematides in the regulation of abundance of fleas of rodents in nature.

[Dependence of the reproductive capacity of fleas on repeated mating (Aphaniptera)]. / Zavisimost' reproduktivnoi sposobnosti u blokh ot povtornosti sparivaniia (Aphaniptera).

The fleas of X. cheopis and C. tesquorum were found to be capable of laying eggs during the whole physiological active period without recurrent fertilization. The recurrent mating and fertilization occur in these species of fleas independently of their age and favour the rise in the abundance of their progeny.