Suitability of different egg ages of Ephestia kuehniella (Lep.: Pyralidae) for the development, reproduction and life table parameters of Trichogramma evanescens (Hym.: Trichogrammatidae)

​Trichogramma evanescens Westwood is an important biological control agent of lepidopteran pests and is widely distributed throughout Iran and neighboring countries. Laboratory studies were conducted to determine the influence of Ephestia kuehniella Zeller eggs age on the number of parasitized eggs, development time, sex ratio, progeny longevity and fecundity. Understanding this influence is important for developing biological control programs. Mated female parasitoids (۲۴ h age) were provided with ۱, ۲, ۳, and ۴-days-old E. kuehniella eggs in no-choice experiments, individually. T. evanescens developed on E. kuehniella eggs of all ages tested, while showing a better adaptation to younger host eggs with significantly faster developmental time, higher survival and more female progeny on ۱-day-old eggs. Progeny emerged from ۱-day-old eggs had also higher longevity and fecundity than those emerging from other host ages tested. The intrinsic rate of increase (r) values of T. evanescens reared on ۱, ۲, ۳ and ۴-days-old E. kuehniella eggs were ۰.۳۴۵, ۰.۳۲۲, ۰.۲۸۱ and ۰.۲۳۳ day-۱ and the mean generation time (T) was ۱۲.۱۹, ۱۲.۱۳, ۱۲.۰۱ and ۱۱.۸۲ days, respectively. The current study provides useful information to use suitable host age of E. kuehniella for mass production of T. evanescens.

Keywords:

egg parasitoid , host age , development time , sex ratio , the intrinsic rate of increase , the mean generation time