Effect of cold storage on the reproductive capacity and longevity of Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead (Hymenoptera: Scelionidae)

Foerster, L. A.; Nakama, P. A.

Female longevity and fecundity of Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead were evaluated at 25 degrees C after storage periods ranging from one to 140 days at 15 degrees C, in intervals of 10 days. The oviposition capacity of both parasitoids was also evaluated at 15 degrees C, following pre-ovipositional periods ranging from one to 60 days, also at 10-day intervals. Females of both species survived for more than five months when stored at 15 degrees C, however fecundity was significantly reduced by the exposure to the low temperature. Despite the reduction in fecundity, both species were able to parasitize host eggs at 25 degrees C after spending 140 days at 15 degrees C. Although parasitism was observed at 15 degrees C, only 3.1% and 0.2% of the exposed eggs were parasitized by T. basalis and T. podisi, respectively. The proportion of males was significantly increased in the progeny of T. basalis females, maintained at 15 degrees C, for any of the storage periods investigated. Similar results were obtained for T. podisi stored at 15 degrees C up to 50 days; however the females of this species, maintained at the lower temperature for longer periods, either laid no eggs or produced progenies with sex-ratio similar to the control insects, kept at 25 degrees C. The presence of females in the offspring of both parasitoid species indicate that mating occurred at the lower temperature. The increased longevity and reduced fecundity of T. basalis and T. podisi obtained when the adults were stored at 15 degrees C, show that both species hibernate, and this arrestment can be useful as a tool for mass production and storage of T. basalis and T. podisi during autumn and winter.