Sexual competitiveness of adult Indian meal moths [Plodia interpunctella] irradiated as mature pupae [Cereal products, insect pests]

When 7-day-old pupae of Plodia interpunctella (Huebner) were treated with 50 krad ..gamma.. irradiation, 94.5 percent of the resulting females mated with untreated males, but the few eggs laid were infertile. Also, resulting males were sterile when they were paired with untreated females. A ratio of 1:1:1 irradiated males, untreated males, and untreated females resulted in 28.5 percent infertile eggs. Ratios of irradiated to untreated males of 5:1, 15:1 or 25:1 produced 54.7, 61.6, and 91.8 percent infertile eggs, respectively. Thus, irradiated males were fully competitive only at a ratio of 25:1. When both irradiated males and females were placed with untreated males and females to give ratios of 1:1:1:1, 5:5:1:1, 10:10:1:1 or 15:15:1:1, the percentages of infertile eggs were 54.1, 95.7, 81.0, and 100 percent, respectively, and competitiveness was good at all but the lowest ratio. Irradiation of 7-day-old pupae of the Indian meal moth produced sexually competitive sterile adults when released at high flooding ratios, and results were better when both sexes were released together.