The role of migrating birds in the transcontinental distribution of entomopathogenic bacteria has been studied not well enough. The purpose of our research is to study the bio-ecological interrelations of Bacillus thuringiensis bacteria with various kinds of migrating birds. As it is known, the involvement of birds into this process occurs through parasitizing of blood- sucking insects and mites on them (Pustovaya, 1971; L´vov, Iliychov, 1979; Novikov, 1984; Olsufiyev, Dunayev and others, 1970). The survival rate of crystal-forming bacteria in the digestive tract of birds was established by W.A. Smirnoff, C.F. Macloed (1961); I.C. Adams, P.A. Hartman (1965). The authors do not exclude the leading role of birds in preservation and distribution of these parasitizing kinds in the external medium. Literary evidences testify that, when studying the ecologo-geographic distribution of Bacillus thuringiensis strains, it was not paid special attention to migrating birds, pathogenic viruses and bacteria have been studied far more deep for that matter.
In different years we carried out microbiological research of the internal organs of migrating birds and 43 entomopathogenic bacteria strains, which are represented by eight subspecies: Bacillus thuringiensis var. thuringiensis (12 cultures); alesti (4); kurstaki (4);sotto (5); subtoxicus (7); kenyae (3); galleriae (6); finitimus (2), were segregated. More than a half of the strains were segregated from the gastric contents. Among animal food birds there are much more bacillicarriers than among vegetal and mixed food. The migration routes of the trapped bird units cross practically all the continents of the Earth, the most visited of which are Africa, South America and Asia. The majority of the examined birds are represented by the species: whoop Upupa epops (L.); common swallow - Hirundo rustica (L.); sand swallow - Riparia riparia (L.); starling - Sturnus vulgaris; rosy pastor - Pastor roseus (L.); gray wagtail - Motacilla cinerea; yellow-headed wagtail - Motacilla citreola (Pall.) and others. We also studied the microflora of biting lice of 11 species in quantity of 162 units collected from wild birds, from which such rare serovars as var. morrisoni, var. kenyae, var. alesti. were segregated.
The variety of the bacteria obtained is conditioned by the fact that birds, especially insect-eating ones, eating various insects, among which there is a high percentage of infected species, become infected with micro-organisms of the Bacillus thuringiensis group, as, however, with other species of viruses and bacteria. This situation is proved by frequent segregation of the strains out of the stomach and intestines of the examined wild birds.
Blood-sucking arthropods, which serve as bacillicarriers, perform a role in birds infecting with the given group bacteria. It is quite possible that the Bacillus thuringiensis strains segregated from the wild birds´ liver is connected with the delivery of the bacterium from the blood-sucking arthropods. The mites, possessing a complex biological cycle of development, being closely connected with the microflora of the external medium, feather and skin integument of its host are constantly infected with micro-organisms of various taxons. According to the data from Petrishcheva P.A. (1967) these contacts promoted the appearance of symbiotic interrelations in mites with many micro-organisms in the process of evolution. However, Bacillus thuringiensis, possessing entomopathogenic properties, can propagate in certain cases in the intestinal opening of insects and mites, the bloodsuckers being most likely ready to deliver the crystal-forming bacteria transmissibly.
From the materials got on the bacteriological examination of the internal organs of wild birds and their ectoparasites one can conclude that birds, especially insect-eating ones, take direct part in the distribution of the given group of micro-organisms, defining their ecological amplitude.
The existence of intercontinental migration paths of birds (on the ringing data more than half of the wild birds examined by us arrive in the CIS territory from South America, South and North Africa, India, Azores and British Isles...) and establishment of a certain percentage of bacilli carriage among their parasites (plumage lice, bloodsucking bugs and mites) allow us to assume that migrating birds perform a significant role of transcontinental exchange of Bacillus thuringiensis strains.
- L´vov D.K., Iliychov V.D. Bird migration and infectious agents´ transmission, M.: Nauka, 1979 -
- Novikov V.G. Meaning of red chicken mite in reservation and accumulation of poultry salmonellas in the environment. - Book: Diagnostics, treatment and prevention of infectious and parasitic diseases of rural animals. Stavropol. 1984 - pp. 14-17.
- Olsufiyev N.G., Dunayev T.N. Natural nidelity: tularaemia epidemiology and prophylaxis. M.: Medicine, 1970 - N3 - p. 270.
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The work is submitted to III Scientific Conference "The Problems of International Integration of Educational Standards", Czechia (Prague) - Luxembourg - France (Paris), April, 20-27, 2008. Came to the Editorial Office 12.05.2008.