Progeny quality of Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae) reared on stored eggs of Homalodisca coagulata (Say) (Homoptera: Cicadellidae)

• Author(s): Chen, Wenlong; Leopold, Roger;
• Abstract: This study assessed the effects of refrigerated storage on the suitability of Homalodisca coagulata (Say) eggs as hosts for propagation of the parasitoid Gonatocerus ashmeadi Girault. Development of host eggs was terminated by chilling at 2C for 5 days before storage was initiated at 10C for up to 70 d. Parasitism, adult emergence rate, development time and sex ratio were used to gauge the suitability of the eggs as hosts after storage. Demographic growth parameters were also used to assess the quality of the wasp progeny through the F2 generation. Host eggs stored 20 d remained fully acceptable to the wasps for attack. Although the parasitism rate decreased with storage time, >80% adult parasitoid emergence was realized from eggs stored 30 days. After 70 d storage, adult emergence rate was decreased by 48%, fecundity decreased by 53%, female production 19%, development extended 3 d, and female longevity was shortened 5 d, respectively. Emergence patterns of F1 but not F2 adults varied with storage time of the parental and grandparental hosts, respectively. The F1 population had a type I survivorship pattern regardless of the length of storage. The F2 generation, emergence rate, development and sex ratio did not vary with storage time when the F1 parents parasitized fresh host eggs. Demographic parameters for the F1 population showed that net reproductive rate was >20 although it decreased significantly after the parental host eggs were stored for >30 days. Intrinsic and finite rates of increase, population doubling time, and mean generation time decreased only after storage for 60 d. Our results show that short-term cold storage could be used for maintaining wasp populations in a mass-rearing program and that the detrimental effects of chilling host eggs in storage for over 30 d do not extend to F2 generation.
• Publication Date: Jan 2007
• Journal: Journal Of Economic Entomology