The use of rapid quality control in determining mating propensity and mating competitiveness of irradiated Mediterranean fruit flies. Ceratitis capitata (Wiedeman) at various ages

Success of using irradiation to sterile males of various insect species for control or eradication by the sterile-insect release technique requires a certain dose for sterilizing without effects on mating behavior. This study was conducted at the Tropical Fruit and Vegetable Research Laboratory, Hawaii, to observe some radiation effects of this laboratory's currently used sterilizing dose on mating propensity and competitiveness of flies. The results of this study would be useful information for future research and use of this technique in Thailand. Mediterranean fruit flies, Ceratitis capitata (Wiedeman) were irradiated with 145 gray of gamma radiation from a cobalt-60 source in a nitrogen atmosphere 2 days before eclosion. Mating behavior of 3-6 day old flies were observed for 3 replications. The test of mating propensity was conducted by using two plexiglas cages containing 25 pairs of irradiated and non-irradiated flies in each cage. The results showed that there was no significant effect on mating propensity of treated 3-5 day old flies (P=0.05), however, treated 6 day old flies, radiation effects were observed. The mating propensity increased with age of both non-irradiated and irradiated flies. Studies on the mating behavior of 20 pairs of non-irradiated and irradiated flies in a competitive situation showed that 3 and 5-6 day old non-irradiated flies of both sexes had higher mating competitiveness than irradiated flies (P=0.01). The irradiated flies were more competitive than the 4 days old non-irradiated flies. Results of possible mating combination between irradiated and non-irradiated flies showed no significant difference in mating index (P=0.05)