Inherited Sterility in Codling Moth (Lepidoptera Tortriciclae): Effect of Substerilizing Doses of Radiation on Field Competitiveness

In release-recapture tests conducted in apple orchards in Oroville, WA, a significant relationship was found between the dose of gamma radiation used to treat adult male codling moths, Cydiapomonella (L.), and the number of males recaptured in virgin female-baited sticky traps. Males treated with 100 Gy responded to calling virgin females in larger percentages than those treated with 200 and 250 Gy. However, the percentage of untreated (released) males captured was lower than the percentage of 100 Gy-treated males captured; a possible explanation for this is that untreated males were moving farther away and were less likely to be near the female-baited traps for recapture. Recapture was highest at days 4 and 5 after release, and significantly more males of all treatments were recaptured when dusk temperatures were at or above 16°C. Radiation also had a negative impact on culling moth mating competitiveness in the field. In mating table experiments, successful matings decreased as the dose of radiation increased. Untreated males were the most competitive among released codling moths.