Effect of Cold Storage on the Quality of Psyttalia incisi (Hymenoptera: Braconidae), a Larval Parasitoid of Bactrocera dorsalis (Diptera: Tephritidae)

SIMPLE SUMMARY: Biological control programs primarily rely on the mass-release of high-quality bioagents in order to successfully suppress pests. However, producing such bioagents on a large scale and within a short timeframe or in a single step is extremely difficult. Therefore, it is important to consider methods that could increase the shelf life and help to synchronize the release schedule of bioagents reared in different batches. In the present study, we determined the effects of various cold storage protocols on the emergence and quality of Psyttalia incisi, a larval parasitoid of Bactrocera dorsalis. Our results indicated that there were no negative impacts on the emergence parameters and adult quality when late-age P. incisi pupae were stored at 13 °C for 10 or 15 d. This information is valuable in facilitating the mass-rearing of P. incisi and helping to improve the efficiency of biological control programs using P. incisi against B. dorsalis. ABSTRACT: Psyttalia incisi (Silvestri) is the dominant parasitoid against Bactrocera dorsalis (Hendel) in fruit-producing regions of southern China. Prior to a large-scale release, it is important to generate a sufficient stockpile of P. incisi whilst considering how best to maintain their quality and performance; cold storage is an ideal method to achieve these aims. In this study, the impacts of temperature and storage duration on the developmental parameters of P. incisi pupae at different age intervals were assessed. Then, four of the cold storage protocols were chosen for further evaluating their impacts on the quality parameters of post-storage adults. Results showed that the emergence rate of P. incisi was significantly affected by storage temperature, storage duration, and pupal age interval and their interactions. However, when late-age P. incisi pupae developed at a temperature of 13 °C for 10 or 15 d, no undesirable impacts on dry weight, flight ability, longevity, reproduction parameters of post-storage adults, emergence rate, or the female proportion of progeny were recorded. Our findings demonstrate that cold storage has the potential for enhancing the flexibility and effectiveness of the large-scale production and application of P. incisi.