The Queensland Fruit Fly (QFF) Bactrocera tryoni is Australia’s most important horticultural pest. The Sterile Insect Technique (SIT) has been used to control this species for decades, but current radiation sterilizing methods can reduce the insects’ abilities to compete for mates. In this study, RNA interference (RNAi) techniques were examined for their potential to sterilize male QFFs without adversely affecting their mating competitiveness. QFF adults were injected or fed double-stranded RNAs (dsRNAs) targeting spermatogenesis genes (tssk1, topi and trxt); quantitative reverse-transcriptase PCR analyses confirmed that transcript levels were reduced 60-80% for all three genes following injections, while feeding produced a 69.1% gene knockdown for tssk1 only. Flies fed with tssk1 and topi dsRNA produced 70% fewer viable offspring than the negative controls. Accessory gland protein transcripts were either unaffected or were upregulated in RNAi-treated males. These findings suggest that RNAi technology could enhance SIT efficacy in these pest insects.