Effects of cold storage after cold acclimation on the fitness of Habrobracon hebetor (Hymenoptera: Braconidae)

Abstract

Habrobracon hebetor (Say) (Hymenoptera: Braconidae) is a cosmopolitan, idiobiont, and gregarious ectoparasitoid, which can parasitize the larvae of several pyralid and noctuid moths. However, adult parasitoids require cold storage to ensure that adequate individuals are available when a pest outbreak occurs. To understand the effects of cold storage after acclimation on offspring fitness of H. hebetor, the development, fecundity, population parameters, and paralysis rate of the F1 generation were evaluated using an age–stage, two-sex life table. Four pairing treatments were used in this study, with refrigerated males and females (ReF×ReM), unrefrigerated females and refrigerated males (UnF×ReM), refrigerated females and unrefrigerated males (ReF×UnM), and unrefrigerated females and males (UnF×UnM, control). Cold storage after acclimation had no significant effect on the fecundity or oviposition period of F0-generation H. hebetor. Moreover, the survival rate (Sa = 61.43%), proportion of females (Nf/N = 0.41), intrinsic rate of increase (r = 0.3450), finite rate of increase (λ = 1.4121), net reproduction rate (R0 = 149.47), and net paralysis rate (C0 = 74.52) of ReF×UnM and UnF×UnM (Sa = 50.00%, Nf/N = 0.34, r = 0.3297, λ = 1.3881, R0 = 155.69, C0 = 62.90, respectively) treatments were significantly higher than those of the ReF×ReM treatment (Sa = 45%, Nf/N = 0.16, r = 0.2277, λ = 1.2558, R0 = 68.81, C0 = 31.61, respectively) (except for the Sa of UnF×UnM treatment), and there was no significant difference between the 2 treatments. Overall, it is advisable to avoid simultaneous cold storage of female and male parasitoids or to add unrefrigerated males appropriately when using cold-stored parasitoids to control pests.