Post-emergence handling procedure for SIT programmes which release sterile flies without chill treatment

Full text: The present work is carried out with the single objective of optimizing the process of handling the biological material in the phase between the irradiation and the release of the sterile insects, for programmes with a release system using bags without chilling. The post irradiation routine handling of sterile insects, at the Bioplanta Km8 (Mendoza- Argentina), is carried out by bagging the irradiated pupae in the 2nd day after the irradiation, and released between 12 to 24 hours after emergence (the 3rd day after the packaging). Considering that irradiated male medfly have their optimal mating age between the 5th-7th day after emergence, there are significant losses between the time of release and when they reach sexual maturity. Current handling procedures involving bags does not allow releases 48 hours post emergence without suffering decreases in the quality of the sterile males. The present proposal allows the maintenance of the adults inside the bags until the 5th day after emergence. In this way flies can be released into the field the day prior to their mating peak. The methodology consists in maintaining the same routine until the moment of the emergence under normal conditions (25 deg.. C-65% Hr.) of the package room. When this has approximately reached 70% emergence, the bags are placed in another room at 17 deg.. C, minimising in this way the activity of the flies, until reaching the release date. The results showed that with the proposed methodology the flies did not suffer qualitative damage during the 5 days of the 'extra' time they were kept in the cold room at 17 deg.. C. The percent emergence was satisfactory in the cold room. Observing the homogeneity of the obtained values and their statistical parameters, we tested the emergence and flight ability between days 1 to 5 after emergence inside the bags with ANOVA (α = 0.05) and we did not find significant differences in the seven times we ran the test. With this new procedure the optimal time of mating was delayed to the 6th to 8th day after emergence as compared to the current 5th to 7th day without the chill treatment. In using the new methodology we can adjust the release time with the optimal mating time, maintaining the quality of the insects released in the field and without having to purchase new and expensive technology. (author)