UAS regulatory sequences drive expression of an shRNA that targets the long isoform of Dsim\gfzf. The shRNA is designed to specifically target the D. simulans Dsim\gfzf gene and not the orthologous D. melanogaster gfzf gene as the shRNA targets a fixed difference between the D. melanogaster and D. simulans orthologs in which the D. melanogaster ortholog contains a deletion compared to the D. simulans sequence.