Interactions affecting female fertility examined in this study expressed as progeny per female per day for mutation/indicated genotype.

Tests were performed to maximise recovery of all adult progeny from the first 15 days of egg laying (see Materials and Methods). Each value is the average from three separate females whose progeny developed on rich medium; an additional three separate progenies that developed on less rich food gave equivalent resultsa.aThis particular set of data was chosen because all of the fertility tests were done within the same time frame; endos/polo1 Scant females can give 20–30 progeny/female/day but they typically lose fertility sooner with age than controls do.