Comparison of Mubarqui diet with yeast hydrolysate as adult diet for Queensland fruit fly Bactrocera tryoni (Diptera: Tephritidae)

Yeast hydrolysate (YH) and sugar is currently the standard adult diet for mass-rearing and pre-release rear-out of Queensland fruit fly (Q-fly) Bactrocera tryoni for sterile insect technique (SIT) programs. YH is a costly protein source, prompting interest in more economical alternatives. As a potential alternative to YH, this study compared (1) the commercial ‘Mubarqui' diet (MD) that is used in Mexican fruit fly SIT programs (2) YH and sugar, and (3) sugar-only (SD) diets in terms of key quality parameters for both production and pre-release rearing. Q-flies fed on MD and SD did not produce any eggs, indicating unsuitability of these diets for fly production. Flight ability of MD- and SD-fed flies was better than the YH-fed flies, which may reflect lower weight owing to lack of reproductive development. Simulating the current practice of holding Q-flies for 5 d to mature at rear-out centers, another experiment was conducted in which each of the three diets was fed to either male or female Q-fly for 5 d and then switched to another to ascertain ongoing need for effective diet and capacity for recovery from inadequate diet after release. Females that received no YH failed to mature, whereas some males retained the ability to mature and mate. Sexual differences in nutritional requirements may enable male-biased operational sex ratio in SIT releases. Flies that received YH showed much greater reproductive organ development than those that received MD or SD diets. Despite effectiveness for some other fruit flies, MD is not suitable as adult Q-fly diet for either production or post-production SIT operations.