Thermal tolerance in adult Mediterranean and Natal fruit flies (Ceratitis capitata and Ceratitis rosa): Effects of age, gender and feeding status

1.Determining the critical thermal limits to activity is a first step towards clarifying how temperature affects population dynamics and geographic distribution of ectothermic insects. However, thermal tolerance may be influenced by a number of factors at the species or population level, including age, gender and feeding status.2.Here, we report the results of experiments investigating the effects of age, gender and feeding status on adult Mediterranean fruit fly (Ceratis capitata) and Natal fruit fly (Ceratitis rosa) thermal tolerance. We measured critical thermal maximum (CTmax) and critical thermal minimum (CTmin) using a dynamic method on different ages (2, 5, 9, 14, 28 days old) and feeding states (recently fed vs. fasted for 48 h) in both genders of adult C. rosa and C. capitata.3.Results show that for the adult life-stage of C. rosa and C. capitata CTmax significantly increases with age up to 14 days. Generally, CTmin also varied with age and 14-day-old flies were the most low temperature tolerant. However, 28-day-old flies in both species generally had poorer thermal tolerance (i.e. narrower thermal range) than younger flies. Feeding significantly improved both CTmax and CTmin while gender had little influence.4.Preliminary comparisons of C. capitata and C. rosa thermal tolerance suggests that both species have similar CTmin (5.4–6.6 °C) but C. capitata have significantly higher CTmax (42.4–43.0 °C) than C. rosa (41.8–42.4 °C). These results support observations that C. capitata inhabits warmer geographic areas than C. rosa. Furthermore, these data are significant for understanding population dynamics under agro-ecosystem conditions and the potential geographic distribution of these species.