title: [The puzzle of Wolbachia spreading out through natural populations of Drosophila melanogaster].
abstract: The endosymbiotic bacteria Wolbachia are widely spread in natural populations of arthropods all over the world. This phenomenon, according to the current views, may be due either to so called reproductive parasitism (modification of sexual reproduction) or to mutualistic interrelationships with the host organism, since the bacteria are transmitted transovarially. Wolbachia are extremely widespread in natural populations and laboratory lineages of Drosophila melanogaster though they do not cause any known modifications of this insect sexual reproduction that could influence the bacteria frequency in the populations. It is found out that Wolbachia effects on drosophila reproductive processes can only consist in low-level of cytoplasmic incompatibility within laboratory lineages; in natural drosophila populations even such an effect has not been detected. The attempts to explain the wide spread of Wolbachia among representatives of D. melanogaster through fitness increasing of infected individuals were not successful either. Data obtained thereupon are contradictive and the results are not versatile. Meanwhile, there are some incomplete data on the bacteria affecting drosophila sexual behavior, expression of certain genes, ferrum metabolism. It is shown that the bacteria enhance individual resistance to RNA-viruses that, under natural conditions, infect fruit flies rather frequently, but the mechanisms of the phenomenon remain uncertain as well as the commonness of the phenomenon itself. Thus, at the one hand, it can be stated that infection by Wolbachia leads to a rather complex effect on D. melanogaster while, at the other hand, the reasons behind the wide spread of Wolbachia in natural populations of D. melanogaster still remain unclear.
authors.forename: S V
authors.initials: SV
authors.lastname: Serga
authors.forename: I A
authors.initials: IA
authors.lastname: Kozeretskaia
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics* / Q000382:microbiology*; D005298:Fertility; D054884:Host-Pathogen Interactions; D011157:Population Dynamics; D012098:Reproduction; D013559:Symbiosis; D020577:Wolbachia / Q000502:physiology*