Impact of hydric stress during pupal development on adult morphology in Ceratitis capitata

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.