Effect of cold storage on biological and morphological characteristics of the parasitoid wasp, Aenasius bambawalei (Hym.: Encyrtidae)

Cold storage is a valuable technique for extending the survival time of parasitoid wasps, but it may have a detrimental impact on their survival and successful oviposition. In this study, we investigated the effect of cold storage of the larval and pupal stages of Aenasius bambawalei at 4°C for two and four weeks on their post-storage developmental time, adult emergence and longevity, female sex ratio, and morphometric characteristics. The highest emergence rate (72%) was observed in pupae after two weeks of cold treatment. In females, the shortest (8.40 days) and the longest (11.40 days) developmental time were seen in pupae and larvae exposed to two weeks of cold treatment, respectively. This trend was also similar in males, and the pupae and larvae subjected to two weeks of cold treatment showed the shortest (10 days) and the longest (11.8 days) developmental period, respectively. The sex ratio and adult longevity decreased significantly with the increase of immature stages’ cold storage period. Additionally, the length of the hind tibia and antennae decreased compared to the control. Based on these findings, we recommend two weeks of A. bambawalei pupae cold storage to increase the survival time of the parasitoid, as cold storage of larvae as well as long period cold storage of pupae, may have negative effects on the adult's fitness.