Effect of different cold storage periods on parasitization performance of Trichogramma cacoeciae (Hymenoptera, Trichogrammatidae) on eggs of Ephestia kuehniella (Lepidoptera, Pyralidae)

The parasitism rates by Trichogramma cacoeciae Marchal (Hymenoptera, Trichogrammatidae) using Ephestia kuehniella Zell. (Lepidoptera, Pyralidae) eggs held at 0, 4 and 8degreesC and for up to 31 days was measured. Parasitism was lowest on eggs held at 8degreesC and highest on eggs held at 0degreesC. The highest parasitism, 97.8%, was measured for parasitoids attacking eggs held for 3 days and stored at 0degreesC. Parasitism of eggs stored at all three temperatures decreased with increasing duration of storage. The number of T. cacoeciae successfully developing and emerging as adults after storage in E. kuehniella eggs held at 0, 4 and 8degreesC was measured. Parasitoid emergence was >83% from E. kuehniella eggs stored at 8degreesC for 3 weeks. Storage at 0degreesC caused a significant decline in parasitoid emergence after 2 weeks (P < 0.05). Storage at 0 degrees C for more than 4 weeks reduced fecundity by 50%. T. cacoeciae parasitized the highest number of E. kuehniella eggs 1 day after adult emergence. The oviposition period lasted 6-7 days, although the parasitoids lived up to 13-14 days. Impact of storage time and temperature on parasitism rates by T. cacoeciae stored while in E. kuehniella eggs was measured. As storage time and temperature increased, subsequent parasitism rates of resulting adult T. cacoeciae decreased. Eggs of E. kuehniella can be stored at 0 degrees C for up to 31 days. Trichogramma cacoeciae developing in eggs of E. kuehniella can be stored at 4 degrees C for up to 5 weeks prior to release.