Abstract: Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is a tomato crop pest. This pest can reduce tomato production up to 90%. The parasitic action of Apanteles gelechiidivoris on third instar larvae of T. absoluta has been documented. The parasitoid A. gelechiidivoris is responsible of around 80% larvae mortality in field conditions. Military University designed and implemented a massive rearing system to release periodically this parasitoid in the field. This system allowed obtaining the parasitoid in the needed quantities with suitable quality. To initiate this process, it was necessary to determine the maximum density of T. absoluta that could be tolerated by tomato plants. It is crucial to ensure a host supply for A. gelechiidivoris. In this study, seven T. absoluta infestation densities on tomato plants were evaluated: 0, 4, 8, 12, 16, 20 and 24 females/plant. The highest densities (20 and 24 females/plant) affected negatively the plant and did not allow T. absoluta to complete its development. The best results were obtained with 12 females/plant, which provided a high production of T. absoluta females and third instar larvae susceptible for parasitism. Subsequently, densities of 4, 8, 12, 16 and 20 T. absoluta females/plant were evaluated to determine its effect on longevity, percentage parasitism and sex ratio of A. gelechiidivoris. The quality variables were not negatively affected when 8 T. absoluta females/plant were used.