Survival of adult females
Of the 96 females in each treatment group, 94% in the control, 92% in
the mating delay, and 65% in the nutritional stress group survived the
100 days of the experiment (Fig. 2a). The hazard of death for adult
females in the nutritional stress group was 6.7 times greater than that
of the control (95% C.I. 2.82 – 16), according to Cox proportional
hazards analysis. The hazard of death for the mating delay group was 1.3
times that of the control (95% C.I. 0.46 – 3.8) (Tables S3.1, S3.2).
The smoothed hazard function indicated increasing risk of death with age
for the nutritional stress group (Fig. 2b) and this was supported by a
better fit to the data using a Weibull survival model in the parametric
analysis, compared with exponential (Weibull ω = 1).
Parametric analysis also provided evidence that the risk of death
increased with age in the mating delay group (Weibull ω = 0.996), but not the control group (Weibull ω = 0.348)
(Tables S4.3, S4.4).