Noninherited sterility in irradiated Phthorimaea operculella females

Newly emerged females of the potato tuber moth, Phthoriniaea operculella (Zeller) (Lep., Gelechiidae), were irradiated with various doses of gamma irradiation: 50, 100, 150 and 200 Gy. Inheritance of deleterious effects in the progeny of irradiated female parents was determined. Phthorimaea operculella females became completely sterile when they were exposed to 200 Gy. Therefore, inherited effects were examined in insects exposed to doses lower than 200 Gy. Developmental time and percentage mortality of F-1 progeny were higher than the control, regardless of the dose. The sex ratio of F-1 progeny was not distorted in favour of either male or female. When F-1 individuals were crossed with unirradiated adults, their mating success, number of matings and number of eggs were similar to those of their irradiated female parents, but lower than the control. In contrast, when F-1 males and females were mated together, the mating success, number of matings and number of eggs were lower than both their irradiated female parents and the control. The fertility of F-1 progeny was higher than that of their irradiated female parents, at all tested crosses. The results showed that the inherited sterility phenomenon did not occur in P. operculella females at the extent known from irradiated males. When the sterile insect technique is used against P. operculella, released females should be completely sterile to prevent any increase in the feral population.