The Mediterranean fruit fly (medfly), Ceratitis capitata (Wied.), like many other polyphagous tephritids (Diptera: Tephritidae), preforms a lek as mating system. The sterile insect technique (SIT) requires released males to survive in the field, and to compete with wild males in attracting, courting and mating with wild females. The effects of the juvenile hormone analogue, methoprene, and the incorporation of hydrolyzed yeast protein into the adult diet, on survival, sexual maturation and sexual performance of male C. capitata were evaluated for the four possible combinations of methoprene-treated or untreated, and protein-fed or deprived flies. The incorporation of protein had a positive impact on laboratory survival and accelerates the sexual maturation of mass-reared males. In addition, in the laboratory, male sexual performance was significantly higher in treatments with methoprene. However, field cage tests with mature and protein-fed wild males and females failed to show any effects of either factor on male sexual performance. The increased survival and the earlier sexual maturation of sterile males due to the addition of protein to the adult diet can positively influence the efficacy of SIT application against C. capitata.