Sublethal effects of methoxyfenozide and emamectin benzoate on Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae)

Trichogramma brassicae Bezdenko is one of the most important egg parasitoid that is released for controlling Helicoverpa armigera (Hübner) in crop fields of Golestan, Mazandaran and Ardebil provinces of Iran. This parasitoid has potential to reduce the pest in agricultural ecosystems. The parasitoid was reared on the eggs of grain moth, Sitotroga cerealella Oliv. (Lep.: Gelechidae) eggs at 26±1℃, 70±5% RH and a photoperiod of 16:8 (L:D) h. The pupal stage of the parasitoid was exposed to the insecticide solutions using dipping method. In this study, sublethal effects of emamectin benzoate and methoxyfenozid were evaluated on the life table and reproduction parameters of T. brassicae. The survivorship was affected by the insecticides. The maximum and minimum of life expectancy was observed in the control and emamectin, respectively. The maximum life span of females was estimated to be 19, 18 and 17 days in the control, methoxyfenozid and emamectin benzoate, respectively. The highest net fertility rate was recorded in the control (86.84 eggs) and the lowest value was observed in the emamectin treatment (23 eggs). Semi field and field studies aiming to assess efficacy of combined use of insecticides and T. brassicae is needed to obtain more applicable results.