Several artificial larval diets have been developed, evaluated and used for mass-rearing of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Teprhitidae). There are several efforts to reduce the cost of rearing and optimize the quality of the produced sterile males that are destined for release in sterile insect release programs. Survival, growth, longevity and reproductive capacity of sterile males are strongly connected with the most expensive ingredient, the brewer’s yeast (protein), in the larval diet. The current study focused on settling the optimal content of brewer’s yeast in a liquid diet and a gel diet. Egg hatch rates, developmental duration of immatures, pupation rate, pupae and adult survival were recorded as indicators of quantity and quality of the produced adults. Egg hatch was higher and larval developmental duration longer in the gel diet. In contrast to the liquid diet, an increase in brewer’s yeast concentration was correlated with increased pupation rate and pupae survival in the gel diet. Reducing brewer’s yeast up to 50% of its initial quantity had no significant effect on the survival of the emerging adults regardless of the diet type. Our findings may contribute to the production of low-cost and effective diets for use in mass-rearing facilities of medflies.

Although temperature is considered the most significant environmental factor influencing the survival, development and fitness of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Teprhitidae), relative humidity also plays a crucial role in determining its performance. Phenotypic plasticity and local adaptation to a variety of climatic regions are known to lead to variation of biological traits among medfly populations. We explored the impact of hydric stress during pupal development on survival and development, as well as on the thermal performance of obtained adults of three geographically isolated C. capitata populations. Medfly pupae from Samar (Israel), Creta and Thessaloniki (Greece), that were reared for few generations in standard laboratory conditions, were exposed immediately after pupation to low (13 ± 2%), moderate (38 ± 2%), standard (56 ± 2%) and high (100%) relative humidity. Weight loss during the pupal stage, pupal developmental duration, survival rate, adult weight and sex ratio, as well as morphometric characteristics of adult size (wings, thorax and head) were recorded. Our results highlight the importance of relative humidity during pupal development. We found that low humidity levels during pupal development increased weight loss, prolonged development and resulted in the emergence of smaller sized adults. Responses to humidity were population specific, as the population originated from the xeric area of Samar had, overall, a better response to low humidity levels compared with those from the more humid areas of Creta and Thessaloniki, indicating greater phenotypic plasticity and suggesting a possible consideration for respective future experimental work.