The performance of parasitism by the egg parasitoid, Trichogramma evanescens Westwood (Hymenoptera:
Trichogrammatidae) on eggs of Angoumois grain moth, Sitotroga cerealella Olivier (Lepidoptera: Gelechiidae) was
investigated under cold storage and gamma irradiation treatments of the host eggs. Cold storage treatment could
improve the parasitoid mass rearing techniques and reduced the costs of biological control programs, while
gamma irradiation might be used as a supplementary support at the times of high demand. The suitability of the S.
cerealella eggs, stored at – 20 °C for 0.5, 1, or 2 h. as a host for T. evanescens was evaluated. The sensitivity of S.
cerealella eggs to gamma irradiation treatments and the acceptability of irradiated eggs for parasitism by T.
evanescens females for the parental P and F1 generations were examined. The results revealed that parasitism was
drastically reduced more than adult’s emergence and sex-ratio (% of females) after cold storage periods of S.
cerealella eggs. Moreover, the parasitism percentages were relatively reduced to (97.1, 96.1, 93.03, and 92.7 %) after
irradiating the S. cerealella eggs at 40, 60, 80, and 100 Gy, respectively than the control (97.3% emergence). The
percentages of emergence and females’ percent were slightly decreased by gamma irradiation doses, while, equal
preferred by the F1 generation of parasitoid that produced from irradiated S. cerealella eggs. |
