INHERITANCE OF PARTIAL STERILITY IN PROGENY OF IRRADIATED MALES OF EPHESTIA CAUTELLA (LEPIDOPTERA: PYRALIDAE) AND ITS EFFECT ON THEORETICAL POPULATION SUPPRESSION

Abstract

AbstractOne-day-old P1 males of the almond moth, Ephestia cautella (Walker), were irradiated with 5, 10, 15, or 2 krad of gamma radiation and paired with untreated virgin females. Progeny were collected through three generations, and lines were established in theF1and F2 with all possible degrees of inbreeding and outbreeding. Radiation effects were assayed by determining mating success, sterility of pairs, average number of progeny/fertile pair, and sex ratio for pairs with males (U♂ × F1♀ U♂ × F2 ♀), females, or both sexes (F1♂ × F1♀, F2 ♂ × F2 ♀) from each dose. Results showed the greater the initial dose, the greater the reduction in the number of progeny and the greater the male to female ratio. Radiation effects on both F1 males and F1 females were greater than effects on the P1 males, though effects on F1 males were greater than effects on F1 females. Except for extinct lines, partial recovery occurred in the F2 generation though recovery was much greater in F2 females than in F2 males. In each generation males were more affected than females from the same breeding line when they were outcrossed with untreated moths. The greater the degree of inbreeding in irradiated lines, the greater the effect on both males and females. Although a high degree of population reduction occurred only in the F1 generation at a dose of 15 and 20 krad, population models showed inbreeding at the lower doses caused sufficient depression to greatly reduce abundance of a natural population for several generations after a single inundative release of substerilized males.