The endosymbiotic bacterium <Emphasis Type="Italic">Wolbachia</Emphasis> enhances the nonspecific resistance to insect pathogens and alters behavior of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

To determine biologically important effects of the cytoplasmic endosymbiont Wolbachia, two substrains of the same Drosophila melanogaster strain have been studied, one of them infected with Wolbachia and the other treated with tetracycline to eliminate the bacterium. Females of D. melanogaster infected with Wolbachia are more resistant to the fungus Blauveria bassiana (an insect pathogen) than uninfected females; infected females also exhibited changes in oviposition substrate preference. Males infected with the bacterium are more competitive than uninfected males. The possible role of Wolbachia in the formation of alternative ecological strategies of D. melanogaster is discussed.