# Intergenerational and Intersexual Differentiation in Respiratory Metabolic Rates of Schlechtendalia chinensis: A Comparison Across Sexuales, Parental Sexuparae, and Progeny Fundatrices

## TL;DR

This study explores how respiratory metabolic rates differ between sexes and generations in Schlechtendalia chinensis, revealing adaptations to non-feeding conditions that impact gallnut production.

## Contribution

The study is the first to elucidate a nutrient adaptation strategy through respiratory metabolic regulation in non-feeding sexual morphs of S. chinensis.

## Key findings

- Males exhibited respiratory metabolic rates 2–3 times higher than females or sexuparae.
- Respiratory metabolic rates peaked at sexual maturity (day 8) and sharply declined post-mating.
- Significant intergenerational and intersexual respiratory metabolic rate differentiation was observed.

## Abstract

The sexual generation of Schlechtendalia chinensis is critical for gallnut production yet cannot feed due to complete mouthpart degeneration. This constraint presents fundamental questions concerning their energy homeostasis: Could modulation of the respiratory metabolic rate serve as an evolutionary adaptation to compensate for nutritional deficits? This study quantified respiratory metabolic rates across key developmental stages of the sexual morphs, encompassing their parental sexuparae and progeny fundatrices. All morphs exhibited lower nocturnal than diurnal respiratory metabolic rates. Males showed respiratory metabolic rates 2–3 times higher than those of females or sexuparae, with those of fundatrices being intermediate. Both sexes displayed a distinct metabolic trajectory: respiratory metabolic rates were elevated at birth, declined initially, peaked at sexual maturity (day 8, coinciding with mating), then sharply declined post-mating. This investigation addresses critical knowledge gaps in the respiratory metabolism of S. chinensis while elucidating an evolutionary adaptation strategy for nutrient allocation through respiratory metabolic regulation under obligate non-feeding conditions. These findings provide actionable insights for optimizing gallnut production within controlled cultivation systems.

The sexual generation of Schlechtendalia chinensis (Bell) is pivotal for gallnut yield yet cannot feed due to mouthpart degeneration. Could respiratory metabolic rate (RMR) modulation compensate for nutritional deficits? We quantified the RMR across key developmental stages of sexual morphs (including parental sexuparae and progeny fundatrices) using an LI-6400XT portable photosynthesis system equipped with a customized insect respiration chamber (6400-89). All morphotypes exhibited significantly lower nocturnal RMRs compared to their diurnal rates (p < 0.05), while RMRs did not differ significantly between morning (9:00–12:00) and afternoon (14:00–17:00) (p > 0.05). Significant RMR variation occurred among morphotypes: females and sexuparae displayed the lowest rates, fundatrices were intermediate, and males exhibited remarkably elevated rates (2–3 times higher than those of females or sexuparae). Both sexes showed a characteristic RMR trajectory: elevated at birth and declining during early postnatal development, followed by a gradual resurgence that culminated in peak values on postnatal day 8, coinciding with mating. This physiological zenith was immediately succeeded by marked respiratory metabolic downregulation following copulation, with RMRs decreasing substantially during the post-copulatory phase. Our findings demonstrate significant intergenerational and intersexual RMR differentiation. This research addresses critical knowledge gaps in the respiratory metabolism of S. chinensis, is the first to elucidate a nutrient adaptation strategy through respiratory metabolic regulation under non-trophic conditions, and provides actionable insights for optimizing gallnut production in controlled cultivation systems.