Response of Bactrocera oleae to different photoperiods and temperatures using a novel method for continuous laboratory rearing

Background: The development of a continuous rearing protocol for the olive fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) remains a fundamental goal of biocontrol programs. We report a new method for continuous smallscale laboratory rearing on olive fruits. The effect of different photoperiod (long and short-day), in combination with two levels of temperature (16 degrees C and 27 degrees C), was verified. Results: Laboratory colonies were successfully maintained on olive fruits for more than 24 months, until project termination. Data showed a short-day photo-phase response: all tested parameters (pupation, emergence, life span, sex ratio) substantially increased on the short-day, except for the emergency rate. Also, changes in the population size were observed in response to photoperiodic condition. There was a significant interaction effect between temperature and photoperiod for pupal stage duration, adult emergence and population size. Conclusion: In earlier and recent literature, most of the rearing procedures adopted long-day photophase and high temperature, but scarce investigation was performed on the effects of the photoperiod on the olive fly. In the present work, we developed a novel method for continuous laboratory rearing of the olive fly on its natural host, which allowed to demonstrate a clear effect of the photoperiod on the effectiveness of the rearing procedures. Laboratory colonies with access to olive fruits showed a short-day photoperiodic response: the optimal combination of climatic parameters was photoperiod 8: 16 LD and temperature 16 degrees C.