Ageing trajectory and longevity trade-off in an aphidophagous ladybird, Propylea dissecta (Coleoptera: Coccinellidae)

The ageing trajectory (trend in ageing) and reproduction-longevity trade-off in both sexes of the ladybird Propylea dissecta were studied. The ageing trajectories of both sexes were investigated in terms of reproductive performance, Using initial oviposition (egg laying within 24 h of mating) acting as ill indicator of the effect of female age and initial viability (percentage of eggs laid within 24 h of mating that hatched) of the effect of male age. Ageing trends were sex dependent, with reproductive performance declining later in females than in males. Initial oviposition of females was largely age dependent and the initial viability of males was age dependent but less so than for females. There is a strong trade-off between number of matings and longevity. Statistical analyses reveal that this trade-off results from an early onset of mortality rather than all increase in mortality rate. A life-span was observed in this ladybird beyond which the longevity did not further decline.