Enhanced survival of mass-reared Mediterranean fruit flies via regular diurnal temperature oscillations

Effectively mass-rearing insects is critical for research, for environmentally friendly technologies like sterile insect technique, producing biological control agents, and enabling novel pest control methods such as those based on genetics or symbionts. While constant temperature conditions are typically used in mass-rearing, at what is considered an optimum value that produces the fittest insects, homeostatic conditions do not reflect the real world. We investigated the performance of mass-reared adult Ceratitis capitata Wiedemann (Diptera: Tephritidae) under constant (24 °C) and oscillating (mean 24 °C with 4 and 10 °C range) temperature regimes. Insect survivorship, flight ability, and female fecundity were assessed across the temperature regimes. Additionally, we compared adult C. capitata performance under environmental chamber and outdoor conditions to determine if temperature and humidity as simulated in the chambers resulted in similar performance outcomes for the insects as being outdoors. Male C. capitata under the 10 °C range treatment had higher survival probability at 55 d postemergence compared to the constant temperature regime, while females showed no significant differences in survivorship among temperature regimes. Flight ability and fecundity were not significantly affected by temperature regimes, though the 10 °C range group showed the highest fecundity. Comparisons between environmental chamber and outdoor conditions revealed minimal differences in performance metrics. Our findings suggest that the field performance of mass-reared male adult C. capitata can be improved by oscillating temperature regimes in mass-rearing facilities.