Serotonergic neuronal death and concomitant serotonin deficiency curb copulation ability of Drosophila platonic mutants.

Drosophila platonic (plt) males court females, but fail to copulate. Here we show that plt is an allele of scribbler (sbb), a BMP signalling component. sbb knockdown in larvae leads to the loss of approximately eight serotonergic neurons, which express the sex-determinant protein Doublesex (Dsx).