Cold storage effects on biological parameters of Telenomus remus, a promising egg parasitoid of Spodoptera frugiperda, reared on Spodoptera litura eggs

Telenomus remus (Nixon) is a promising egg parasitoid for the management of Spodoptera frugiperda (J. E. Smith). This species has been successfully reared on alternative hosts under laboratory conditions. However, the production of biocontrol agents is often out of sync with the demands in the field. Appropriate cold storage techniques can drastically prolong their shelf-life to synchronize the release schedule with field needs and reduce production costs. Past studies on the cold storage of T. remus only focused on certain developmental stages, but not all stages. Here, we comprehensively evaluated the impacts of storage temperature (8, 11, and 14 °C) and duration (7, 14, 21, 28, and 35 days) on the maternal emergence and offspring fitness of T. remus stored at different developmental stages (first instar larvae, second instar larvae, prepupae, and pupae) using Spodoptera litura (Fabricius) eggs as alternative hosts. For each developmental stage, emergence percentage and parasitism capacity of parents all decreased with increased storage duration and decreased storage temperature. Maternal female longevity, offspring emergence percentage and percentage of females were barely affected by cold storage. We concluded that storage of the first instar larvae at 14 °C for 21 days was the optimum storage scheme for T. remus. Our findings can be directly used as guidance in mass production and storage of this parasitoid.