Female-specific doublesex dsRNA interrupts yolk protein gene expression and reproductive ability in oriental fruit fly, Bactrocera dorsalis (Hendel)

A homologue of the doublesex gene (Bddsx) has been cloned from the oriental fruit fly, Bactrocera dorsalis (Hendel). Northern analysis indicates a differential expression of Bddsx in male and female flies, as reported for other dsx genes. A structural conservation of DNA binding domain/oligomerization domain 1 and oligomerization domain 2 suggests that the doublesex protein (BdDSX) of this fruit fly serves as a transcriptional factor for downstream sex-specific gene expression. The putative transformer/transformer-2 protein binding sequence in female-specific transcript suggests that a preserved alternative splicing process found in other flies mediates the synthesis of Bddsx transcript. RNA interference (RNAi) data from adult abdominal dsRNA injection assays indicate that female-specific dsx dsRNA reduces specifically its own transcript, inhibits selectively expression of the yolk protein gene (Bdyp1), and delays ovary development. The number of matured eggs is significant reduced after RNAi treatment, but the sex ratio of offspring is not biased. Moreover, 27% of female progeny with RNAi show deformed ovipositor, but male flies are not affected. Although this is a transient treatment, the specific Bddsxf interference offers a promising and novel approach to oriental fruit fly control in the future.