Suitability of Ephestia kuchniella (Zeller) (Lepidoptera: Pyralidae) eggs for parasitisation by Trichogramma evanescens Westw and Trichogramma cacoeciae Marchal (Hymenoptera: Trichogrammatidae)
2003
El-Mandarawy, M.B.R. (Agricultural Research Center, Giza (Egypt). Plant Protection Research Inst.)
Suitability of Ephestia kuehniella (Zeller) eggs at various ages (2, 4, 8, 12, 24, 48 or 72-h-old eggs), as a substitute host for rearing Trichogramma evanescens Westw. and Trichogramma cacoeciae Marchal, were tested. Also, the effect of chilling on hatching and parasitism of E. kuehniella eggs (greater than 24-h- old) at 2, 4, 8, 12, 24, 48 and 72 chilling hours by the two Trichogramma species was studied. Eggs, at 28 degree centigrade and 50-60% R.H., only 2 hold were not very attractive to the two parasitoid species. In general, the number of host eggs attacked, decreased with increasing age. The highest rate of parasitism occurred at 4 h and the lowest at 72 h. However, eggs of all ages proved suitable for the development of T. evanescens and T. cacoeciae, with no significant differences in the emergence rate from E. kuehniella eggs. Moreover, T. evanescens was more suitable for biological studies on of E. kuehniella eggs than T. cacoeciae. When E. kuehniella chilled eggs (greater than 24-h-old) for 2, 4, 8, 12, 24, 48 or 72 h, at -1 degree centigrade, were exposed to the female of the two-trichogrammatid species, the rate of parasitism was diminished as the period of chilling increased. Prolonged exposure of eggs to cold resulted to the death of embryos and reduced hatching.
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