Y.-X. Sun, C. Tong & T.-X. Liu Influence of larval rearing temperature on the quality of cold-stored Oomyzus sokolowskii Kurdjumov (Hymenoptera: Eulophidae)

Influence of larval rearing temperature on the quality ofcold-stored Oomyzus sokolowskii Kurdjumov (Hymenoptera:Eulophidae)

Y.-X. Sun, C. Tong & T.-X. Liu 

JOURNAL OF APPLIED ENTOMOLOGY

DOI: 10.1111/jen.12326

Abstract:  Oomyzus sokolowskii, an important parasitoid of Plutella xylostella, has great potential for use in biological control. Storage at suboptimal temperature is valuable for increasing the shelf-life of insect parasitoids. In this study, O. sokolowskii larvae were reared at 30/25, 25/25 and 25/20°C light/dark (65 ? 5% RH, 16 : 8 h L : D) until pupation. The pupae were then cold-stored at 4 ? 1°C (60 ? 5% RH, full darkness). The pupae were removed out from the storage at 10, 20, 30 and 40 days after storage (DAS) and maintained at 25 ? 2°C until adults emerged or pupae died. Quality ofthe emerging adults and their F 1 offspring were assessed. Incidence of parasitism by O. sokolowskii was higher at 30/25°C than at 25/20°C. Cold storage of O. sokolowskii pupae greatly affected the fitness of the parasitoid: adult emergence rates were lower in the 40 DAS treatment than in other treatments; when O. sokolowskii larvae developed at 25/25°C, female proportions of the emerged adults were lower in the 40 DAS treatment than in the 0 and 10 DAS treatments. Larval rearing temperature mildly affected the adult emergence rate, post-storage developmental time and female proportion with a few exceptions. Number of parasitoids emerged per host pupa, and incidence of parasitism by the females were neither affected by larval rearing temperature nor cold storage duration. Trans generational effects on F 1 offspring were evident in adult emergence rate, egg-adult developmental time and female proportion which were negatively affected by long duration of storage (40 days), but not by larval rearing temperature with a few exceptions. In conclusion, O. Sokolowskii pupae could be stored at 4°C for up to 30 days without significant fitness loss.