Effect of Cold Storage on Emergence, Longevity, Fertility, and Survival of Cotesia marginiventris (Hymenoptera: Braconidae)²

The effect of short-term cold storage on non-diapausing pupae and adults of Cotesia marginiventris (Cresson) was evaluated for developing protocols for the mass production of this parasitoid. When stored at 10°C, successful emergence of adults from cocoons occurred within 6 d and was not affected by storage time (0 d, 4 d, 12 d, or 20 d). Longevity of males and females was not affected by cold storage, but fewer males and females remained alive per consecutive 8 d interval after emergence at 27°C. A fertility experiment revealed that fewer progeny (F₁ cocoons, F₁ females) were produced by parental females previously cold-stored as pupae in cocoons for 20 d rather than 4 d. A within-storage adult survival experiment demonstrated that males and females were not affected by any of the storage times (8 d, 16 d, 24 d, 32 d). This survival rate was achieved by removing the adults from the cold at 8 d intervals, placing them at 23 ± 1 °C for ~ 2 h and providing honey. Another fertility experiment revealed that more F₁ males, but fewer F₁ females, were produced when the parental females (which had been cold-stored as adults) were stored for 32 d rather than for 16 d. This study suggests that adults are more amenable to short-term storage than pupae if the adults are periodically removed for feeding. Nevertheless, cold storage of cocoons (pupae) for 20 d or adults for 32 d can limit the production of female progeny.