Influence of temperature and exposure time of cold storage on the fitness of Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae)

Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) is an important biological control agent that parasitizes larvae and pupae of Coleopteran pests. Cold storage can extend the shelf life of parasitoids for use in biological control programs. To understand the effects of cold storage on performance of A. calandrae, the adult survival, longevity, parasitism rate, and fecundity of A. calandrae after cold storage were investigated. Newly emerged A. calandrae females were stored at three constant temperatures (5, 10, and 15 °C) for 1, 2, 3, 4, 5, and 6 weeks. Both temperature and storage period significantly affected longevity, parasitism, progeny, and sex ratio of A. calandrae. Significant reduction in longevity was observed at 5 °C. After 1 week of cold storage, the longevity of A. calandrae at 5 °C decreased to 8 d, compared to 11 d in the control. However, there was no significant difference on the longevity and parasitism rate when the female wasps were stored at 15 °C for 3 weeks compared to control. The number of progeny gradually decreased with increasing storage period at 15 °C, and the maximum of progeny was observed for the control, 83.33 followed by 75.46 (1 week), 71.26 (2 weeks), and 68.40 (3 weeks). After cold storage at 5 °C for 1 week and 15 °C for 3 weeks, female-biased sex ratios in progeny were 0.53 and 0.55, respectively. Overall, storage at 15 °C for 3 weeks had the least negative impact on adult survival, longevity, parasitism rate, and progeny of A. calandrae wasps.