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.

Methods
Description of methods used for collection/generation of data: We collected data on pupal mass, adult mass at emergence, daily sugar water consumption, daily egg production, resting metabolic rate, flight metabolic rate, body mass, total number of eggs and lifespan.

The methods are described in the associated article.

Methods for processing the data: CO2 production data were converted from concentrations to metabolic rates using standard equations, see Lighton, J. R. B. (2008).

Measuring Metabolic Rates: A Manual for Scientists. New York: Oxford University Press.

Instrument- or software-specific information needed to interpret the data: n/a

Standards and calibration information, if appropriate: n/a

Environmental/experimental conditions: Experiment carried out in greenhouse. 16:8 h light:dark and 27:16 °C temperature cycle.

Describe any quality-assurance procedures performed on the data: n/a

People involved with sample collection, processing, analysis and/or submission: Gladys Delgadillo, Brad Huang, Mattias Lanas, Clare LeDuff, Morgan McCluskey, Alejandra Mejia, XiaoSong Mu, Anika Naidu, Simon Scarpetta, Charlotte Wayne, and Amy Zuckerwise helped in data collection.