none A single meal of cis-diamminedichloroplatinum (DDP) fed to virgin braconid wasps decreased drastically the number of eggs derived from oogonia. In contrast, most of the larger oocytes completed oogenesis even after a dose which shortened average lifespan to 1/3 its normal length. Temporary infecundity resulted from the destruction of the germarial cells which produced the 32 cystocytes per follicle (1 oocyte and 31 trophocytes) by mitosis. As determined by egg hatchability, oogonia were the most vulnerable cell type to DDP in the ovariole sequence. Therefore, oogonial vulnerability to DDP was demonstrated by failure to complete both gametogenesis and embryogenesis. In combination with gamma radiation, DPP reduced egg production and hatchability below the values obtained from either agent used alone.