Combined effects of dietary yeast supplementation and methoprene treatment on sexual maturation of Queensland fruit fly

Yeast hydrolysate supplements promote maturation of many tephritid flies targeted for control using the sterile insect technique (SIT), including Queensland fruit fly (Bactrocera tryoni; ‘Q-fly’). Recently, application of the juvenile hormone analogue methoprene has been demonstrated to further promote maturation in some species. We here investigate the separate and combined effects of yeast hydrolysate and methoprene treatment on sexual maturation of sterile male and female Q-flies. Two methods of applying methoprene solution were used; topical application to adults and dipping of pupae. Consistent with previous studies, access to yeast hydrolysate greatly increased maturation of both male and female Q-flies. Maturation was further promoted by methoprene treatment, with similar effects evident for males and females and for both application methods. For flies provided access to yeast hydrolysate supplements, methoprene treatment advanced maturation by approximately 2 days. No effects of diet or methoprene treatment were found on timing of copulation or copula duration. Countering the positive effects on sexual maturation, dipping of pupae in methoprene/acetone solution did diminish emergence rates and flight ability indices, and increased rates of wing deformity. Promising results of the present study encourage further investigation of treatment methods that maximise maturation while minimising detrimental effects on other aspects of fly quality.