The limit of tolerance to temperature treatments that a developing embryo of Ceratitis capitata is able to withstand without suffering a reduction in hatchability or an increase in late abortions was investigated. Major events during embryogenesis were timed and the observation of the chitinous mouth hook inside unhatched eggs was chosen as a marker of late embryo death. This late abortion production was investigated in three different embryo stages and using two pulse lengths. It was found that an exposure of embryos aged 16 hr after egg laying (right before the beginning of the head involution) to 35°C for a period of 15 hr is close enough but below the limit of tolerance for the strain T (Y-nig+)5038 used in this investigation. Consequently, this exposure is proposed as the discriminating treatment in a screening protocol designed for the isolation of a temperature-sensitive embryonic-lethal mutation.
