Marianne Frommer is internationally renowned for the invention of bisulphite genomic sequencing, in which bisulphite-modified DNA is amplified with strand-specific PCR primers to provide an accurate map of cytosine methylation, a critical epigenetic determinant. The technique is used worldwide in mammalian developmental genetics and cancer diagnostics. Her previous seminal work was in characterising CpG islands, including work used for search protocols of genome databases today. She later applied her molecular analytic skills to the important, practical and difficult problem of controlling Queensland fruit fly, Australia's major horticultural pest, thereby providing major advances in control, and in understanding the molecular genetic bases for behaviours and speciation.