مشخصات پژوهش

Eggs of hosts may be kept in a refrigerator for up to 30 days without losing their viability as hosts for Trichogrammatid egg parasitoids. However, parasitoids reared on refrigerated eggs may have been reduced performance because of long exposure of host eggs to low temperatures and reduces host quality. The objective of this study was to evaluate the suitability of Anagasta kuehniella Zeller and Phthorimaea operculella Zeller eggs stored at 4°C for different time periods as a host for Trichogramma brassicae Bezdenko. Hosts eggs were subjected to 6 storage periods (0, 1, 4, 7, 15 and 30 days in a refrigerator at 4°C and the control without storage) were used. Then, eggs were placed inside a microtube with a single 1-day old parasitoid female at 26±1°C, RH: 65±10% and 16:8h L:D photoperiod separately. After this period, the cards with each hosts eggs were transferred to glass tubes until emergence of T. brassicae adults at the mentioned standard condition. 10 replications were considered for each host. The parasitism rate, adult emergency rate, longevity and sex ratio were analyzed with factorial design using SAS and means were separated at the 5% significance level by using Duncan test. The highest parasitism was observed in control treatment of P. operculella (82.76%) followed in control treatment of A. kuehniella (73.33%). The mean of this parameter in 1, 4, 7, 15 and 30 days’ storage of P. operculella eggs were 72.9, 52.33, 59, 55 and 29.67% and for A. kuehniella were 62.67, 51.33, 44, 28.33 and 15.33%, respectively. There were significant differences between control and 30 days in both hosts. The least adult emergency percentage (31.89%), sex ratio (23.53% female), longevity (4.48 d) were in 30 days’ storage of P. operculella eggs and the least of fecundity (28.7 eggs per female life span) was in 15 days’ storage of A. kuehniella eggs. The mean of adult emergency percentage in 1, 4, 7 and 15 days’ storage of P. operculella eggs were 75.79, 67.81, 74.01 and 70.32