Queensland fruit fly (Bactrocera tryoni; Q‐fly) pupae are routinely irradiated to induce reproductive sterility in adults released in a sterile insect technique programme. Although there have been some studies of how total dose influences fly quality, dose rate has not been considered. In the present study, pupae were irradiated at a target dose range of 70–75 Gy at dose rates of approximately 5, 7, 26, 57 and 80 Gy/min and were then subjected to routine IAEA/FAO/USDA quality control tests including emergence, flight ability, mortality under stress and sterility induction. No significant effects of dose rate were found on emergence or flight ability. Sterility induction was also found to be independent of dose rate, a result conforming to a ‘one‐hit’ ionizing event hypothesis. Flies irradiated at higher dose rates suffered increased mortality under stress. This appears to stem from an increased tendency to over‐shoot the target dose when irradiating at high dose rates. We recommend that, to reduce potential error in total target dose, the lowest practical dose rate be used when irradiating Q‐fly pupae for use in the sterile insect technique.

The current study is an important step toward calibrating, validating, and improving irradiation methods used for Bactrocera tryoni (Froggatt) sterile insect technique (SIT). We used routine International Atomic Energy Agency/U.S. Department of Agriculture/Food and Agriculture Organization quality control tests assessing percentage of emergence, flight ability, sex ratio, mortality under stress, reproductive sterility, and sexual competitiveness, as well as a nonstandard test of longevity under nutritional stress to assess the impact of a range of target irradiation doses (60, 65, 70, 75, and 80 Gy) on the product quality of mass reared B. tryoni used in SIT. Sterility induction remained adequate (>99.5%) for sterile male-fertile female crosses, and 100% sterility was achieved in fertile male-sterile female crosses and sterile male-sterile female crosses for each irradiation doses tested. There was significant increase in mortality under stress as irradiation dose increased, and reduced participation in mating by males irradiated at higher doses. The current target-sterilizing dose for SIT of 70-75 Gy is associated with significant reduction in fly product "quality". Our data suggest that adequate sterility and improved fly quality could be achieved through a small reduction in target sterilizing dose.

The sterile insect technique has been routinely used to eradicate fruit fly Bactrocera tryoni (Froggatt) incursions. This study considers whether fly quality in a mass-rearing facility can be improved by reducing irradiation doses, without sacrificing reproductive sterility. Pupae were exposed to one of five target irradiation dose ranges: 0, 40-45, 50-55, 60-65, and 70-75 Gy. Pupae were then assessed using routine quality control measures: flight ability, sex ratio, longevity under nutritional stress, emergence, and reproductive sterility. Irradiation did not have a significant effect on flight ability or sex ratio tests. Longevity under nutritional stress was significantly increased at 70-75 Gy, but no other doses differed from 0 Gy. Emergence was slightly reduced in the 50-55, 60-65, and 70-75 Gy treatments, but 40-45 Gy treatments did not differ from 0 Gy, though confounding temporal factors complicate interpretation. Reproductive sterility remained acceptable (> 99.5%) for all doses--40-45 Gy (99.78%), 50-55 Gy (100%), 60-65 Gy (100%), and 70-75 Gy (99.99%). We recommend that B. tryoni used in sterile insect technique releases be irradiated at a target dose of 50-55 Gy, providing improved quality and undiminished sterility in comparison with the current 70-75 Gy standard while also providing a substantial buffer against risk of under dosing.

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In this study, we demonstrate for the first time the successful fabrication of well-dispersed ultrafine silver nanoparticles inside metal–organic frameworks through a single step gamma irradiation at room temperature.

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