The impact of cold storage on mating behavior of emerging adults and progeny fitness, in a parasitoid wasp, Lysiphlebus fabarum, under constant and fluctuating temperatures

Cold storage is a valuable method for reducing the cost of producing large amounts of biological agents. Fluctuating thermal regimes (prolonged exposures at low temperatures combined with periodic short higher temperature) are reported to improve cold survival and fecundity in some parasitoid species. In this study, the pupal stage of the parasitoid wasp Lysiphlebus fabarum (Marshall) (Braconidae: Aphidiinae), within mummies of Aphis fabae were stored for a period of two weeks at 6±1°C (50–60% RH, L14:D10 photoperiod), and the mating behavior of emerging adults and fitness of their progeny were compared under fluctuating thermal regime (2 h daily at 21°C) versus constant low temperature. Results revealed that the males emerging from fluctuating temperature regime, in contrast to constant temperature treatment, were not significantly different from the control males in odour recognition, walking speed, and number of mating success. Moreover, the fitness of the first generation progenies (percent parasitism, percent adult emergence and sex ratio) was not influenced by cold storage under fluctuating temperature treatment. Our results confirmed that cold storage of L. fabarum pupae under fluctuating regime is a protection method when compared to constant low temperature exposure.