Cold storage effects on maternal and progeny quality of Gonatocerus ashmeadi Girault (Hymenoptera : Mymaridae)

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This study determined the effects of cold storage on the survival, development and reproduction of the mymarid wasp, Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae). Following storage of the immature parasitoids within host eggs of the glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) under a daily fluctuating temperature for up to 50 d, the quality of the parental and F, generations was assessed by examining several reproductive and developmental parameters indicating fitness. Immature wasps were stored for 20 d within the host without reducing their subsequent survival, development or progeny fitness parameters. After 30 d of storage, survival declined, post-storage developmental time was extended, and the fecundity of the adult females decreased. Storage for 40 d severely damaged G. ashmeadi, because it not only yielded a 12% survival rate, 44% female sterility and increased the proportion of progeny males by 155%, but it also reduced parasitism and fecundity by 70% and 73%, respectively. No wasps emerged after 50 d of storage. Cold storage affected the emergence pattern of the parental but not the F-1 and F-2 generations. Parental emergence was extended and the pattern displayed two additional peaks after the initial onset. Analysis of several demographic parameters for the parental and F, generations further confirmed that the quality of the adult parents declined after they had been stored as immatures for 30 d. The detrimental effects caused by cold storage of the parental generation do not extend to the F, generation. Our results indicate that short-term cold storage of G. ashmeadi within its host could be used for maintaining and accumulating these parasitoids during mass propagation for release in a control program. Published by Elsevier Inc.


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