Optimization of cold storage conditions for Meteorus pulchricornis (Hymenoptera: Braconidae) applied in the biological control of fall armyworm.

Cold storage is commonly used in the mass rearing of parasitoid wasps, but its consequences for post-storage performance are often species- and stage-specific. Here, we examined how storage temperature, developmental stage, and storage duration affect survival, emergence, biological traits, and parasitism of Meteorus pulchricornis (Wesmael). Survival and emergence varied strongly among treatments. Pupae tolerated low-temperature storage better than adults, and the detrimental effects could be minimized by an appropriate combination of storage temperature and development stage. Increasing storage duration resulted in smaller adult body size, shorter lifespan, reduced fecundity, and darker cuticle pigmentation, indicating progressive sublethal effects of cold exposure. Cold storage further influenced parasitic performance and functional response. Overall, the post-storage quality of M. pulchricornis depended on developmental stage and storage conditions, and storage of early-stage pupae at 10 °C provided the most suitable balance between storage feasibility and biological performance, although biological quality declined with increasing storage duration.