Sex differences in developmental response to yeast hydrolysate supplements in adult Queensland fruit fly

Post-teneral dietary supplements have been found to improve mating performance of male Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) (Q-fly) and show considerable promise for enhancement of sterile insect technique (SIT) programmes even when applied within the current 48h pre-release holding period. However, Q-flies are released as a bisexual strain, and the positive effects of a diet including yeast hydrolysate for males may also boost reproductive development and sexual performance of females. Increased prevalence of mature sterile females can substantially dilute SIT efficacy as mating capacity of sterile males is largely depleted by sterile females rather than the relatively rare wild females. Here, we demonstrate that providing yeast hydrolysate for 48h after adult emergence, emulating the current pre-release holding period of Q-fly SIT, leads to a significant increase in reproductive development and sexual performance in male Q-flies. In contrast, female Q-flies with access to yeast hydrolysate for 48h had ovaries that were poorly developed and, particularly at younger ages, were less likely to mate and remate than females with continuous, ad libitum access to yeast hydrolysate. Our findings suggest that addition of yeast hydrolysate into the pre-release diet of Q-flies could be a cost-effective means of releasing a bisexual strain with competitive males but with sexually immature females, thereby rendering it operationally more similar to a unisexual strain.