Carry-over effects of larval food stress on adult energetics and life history in a nectar-feeding butterfly

Stressful juvenile developmental conditions can affect performance and
fitness later in life. In holometabolous insects such as butterflies,
development under stressful conditions may lead to smaller adult size,
lower reproductive output and shorter lifespan. However, how larval
developmental stress affects energy intake and expenditure in adult
individuals is poorly understood. We subjected last-instar larvae of
Speyeria mormonia Edwards (Lepidoptera: Nymphalidae) to periodic dietary
restriction (DR) to examine the allocation of energy and nutrients among
different life-history processes. We measured adult food intake, resting
metabolic rate (RMR), metabolic flight capacity, lifespan, and
reproductive output. Consistent with pressure to disperse from a poor
environment while maintaining offspring number, we predicted that stressed
individuals would have increased adult food intake and higher flight
capacity. Adult body size was strongly reduced. Contrary to predictions,
we found no compensatory adult feeding. Mass-adjusted flight metabolic
rate was reduced, suggesting poor dispersal capacity. Larval DR did not
affect adult lifespan, nor did the rate of metabolic senescence change.
Larval DR did affect RMR, as stressed females had a steeper slope between
RMR and body mass, which may reflect differences in physiological activity
due to condition. Fecundity decreased less than predicted based on body
mass. Instead of investing in flight capacity, females increased relative
allocation to reproduction, which may partly buffer against poor
environmental conditions. Understanding the interplay of energy
acquisition and allocation to life history traits across the life cycle is
vital for predicting responses to environmental change.