Transfection of Wolbachia in Lepidoptera: the feminizer of the adzuki beanborer Ostrinia scapulalis causes male killing in the Mediterranean flour moth Ephestia kuehniella

Two species of Lepidoptera, Ostrinia scapulalis and Ephestia kuehniella, ha rbour Wolbachia, which are maternally transmitted intracellular bacteria th at often cause reproductive abnormalities in arthropods. While the infectio n in O. scapulalis causes conversion of genetic males into functional femal es (feminization), that in E. kuehniella induces cytoplasmic incompatibilit y In the present study we investigated the relative importance or host and Wolbachia factors in the differential expression of reproductive alteration s in these insects. We transferred the Wolbachia harboured by O. scapulalis to E. kuehniella in which the original infection had been cured by tetracy cline treatment. The transfected strain of E. kuehniella expressed a matern ally inherited, female-biased ses ratio. Unexpectedly two lines: of evidenc e suggested that the srs ratio distortion was due to malt, killing. First, higher mortality of young larvae was observes. Second, the removal of the t ransferred Wolbachia resulted in tile recovery of a 1:1 sex ratio, whereas the removal of a feminizer should result in a male-biased sex ratio among o ffspring. To, the authors' knowledge, this is the first report that a singl e Wolbachia strain call cause two distinct sexual abnormalities in differen t hosts. Our observations highlighted the importance of host-Wolbachia inte ractions in determining the phenotype of reproductive alterations.