Genomic fragment that encompasses osk, in which the portion of the osk gene from just 3' to the start of the second exon to the stop codon (coordinates 3R:8935984..8937367 , release 6 genome) has been replaced with synthetic sequence that retains the wild-type intron sequences and encodes the wild-type protein, but with synonymous codons to maximize differences in the DNA sequence. These changes render the transgene resistant to RNAi mediated by P{UAS-osk.RNAi.3}.