Butterfly fitness under changing food qualities

The present thesis investigates how different food qualities over the whole life cycle and
across generations affect butterfly development and reproduction, and addresses the following
main questions: (1) What effects have varying nitrogen concentration and different levels of
host plant defence during larval phase on larval and adult performance in butterflies? (2) Can
adult feeding in male and female butterflies compensate for deficiencies acquired during the
larval stage, or even increase butterfly fitness and reproductive success? (3) Does parental
food quality affect the next generation by parental effects (increased provisioning to
offspring, maternal oviposition choice or transgenerational acclimatization)?
With six distinctive experiments, I show that butterfly reproduction and fitness significantly
correlate with food quality and quantity. Thus, there are diverse strategies over the whole
butterfly life cycle to deal with suboptimal food sources in order to maximize reproduction
and fitness. First, during the larval stage, larval feeding duration can be prolonged and relative
consumption rates and/or efficiency of larval nitrogen utilization could be increased to
compensate for low-quality larval host plants. Second, adult nectar diet can compensate for
deficiencies acquired during larval stage and generally enhance reproduction. Furthermore,
female butterflies can use male-derived nuptial gifts for egg production. Third, parents can
increase provisioning to offspring and acclimatize and oviposit progeny to anticipated host
plants by transgenerational acclimatization to increase offspring performance and fitness.
These diverse strategies during larval and adult stage and even trans-generationally to
maximize reproduction and fitness show that butterflies are well adapted to quickly changing
host plant supplies. Furthermore, it shows that the holometabolous life cycle, using different
food sources during larval and adult stage, is a favorable surviving strategy.