Use of gamma radiation to sterilize Ceratitis capitata (Wied., 1824), tsl VIENNA 8 strain, for application of sterile insect technique in Brazil

The Sterile insect technique is a method of pest control allowed in integrated pest management programs in fruit growing, where sterile insects released compete in mate process against fertile wild ones, generating a gradual population reduction. The most used sterilization method is using ionizing radiation from 60Co or 137Cs. For efficient application of SIT, an important item is the sterilizing dose. This must be as lower as possible in order to preserve insect behavior. In this work, it was studied the reproductive potential of fruit fly Ceratitis capitata, tsl VIENNA 8 strain, irradiated with different doses of gamma radiation. This strain shall be used in population suppression programs at fruit-growing areas from Northeast of Brazil, through a partnership between CENA and Biofactory MOSCAMED Brazil, intending only sterile male releases. Radiation source used was a 60Co irradiator, with 17.2 .1012 Bq. Individualized couples were distributed in a randomized delineament with 10 replicates for each treatment and eggs were collected for fifteen days. With 9 and 10 days old, pupae were irradiated with doses ranging from 30 to 120 Gy. All means of emerged adult's percentages were higher than 90%. In regards to fecundity, different doses didn't affect the number of eggs laid, being the overall mean around 30 eggs/couple/day. Fertility data showed that as radiation dose increases, sterility increases. It was concluded that the dose of 90 Gy could be used in Brazil, since to SIT programs a dose is chosen witch prevents an egg hatch higher than 1%. (author)