Gamma Irradiation of the Mediterranean Fruit Fly (Diptera: Tephritidae): Effects of Puparial Age under Induced Hypoxia on Female Sterility

Abstract

Female Mediterranean fruit flies, Ceratitis capitata (Wiedemann), were subjected to sterilizing doses of 15 krad CO60 in a nitrogen atmosphere at the late puparial and newly emerged adult stages. Ovarian dissection and cross-mating experiments were conducted to determine whether egg development is enhanced during maturation of the puparial content and whether hypoxic atmospheres during irradiation might contribute to egg viability. When irradiated 2 days before eclosion, germinal ovarian tissue was severely damaged and no eggs occurred. However, a logarithmic increase in eggs was discovered in adult females from pupae irradiated 1 day before emergence, 3 h before emergence, and 3-h-old adults. Although no regeneration of germinal tissue was found, retention of eggs in the ovaries for varying lengths of time simulated “recovery of fertility.” Replicated cross matings with irradiated males of the same age distribution produced no offspring. However, matings of normal males A— females from pupae irradiated a few hours before emergence and newly emerged, produced viable offspring. The surviving F1, generation mated and produced a normal complement of eggs. This report describes discovery of a mechanism for remnant fertility which, if present in a pest species of such high reproductive potential, could adversely affect the success of sterile insect technique application.