# Nymphal diets boost adults’ immunity via strengthened constitutive immunity and metabolic capacity in Adelphocoris suturalis

## TL;DR

Eating a varied diet as a nymph boosts an insect's adult immunity and metabolism, helping it better resist infections.

## Contribution

The study reveals a developmental link between early omnivory, metabolic activity, and enhanced immunity in insects.

## Key findings

- Adults from omnivorous nymphs showed higher survival against fungal infection.
- Omnivorous diets increased immune gene expression and enzyme activity in early infection stages.
- Metabolic gene up-regulation in omnivorous adults correlated with stronger immune responses.

## Abstract

In insects, juvenile diet strongly influences adult fitness. Yet, despite the centrality of immune function to overall organismal health, the effects of early-life diets on adult immunity remain underexplored. We showed that Adelphocoris suturalis adults, developed from nymphs fed on an omnivorous diet (NO), exhibited higher survival against Beauveria bassiana than those from a phytophagous diet (NP). Using high-throughput RNA sequencing, we profiled gene expression responses at both early and late infection stages. Integrated transcriptomic and immunological analyses revealed that NO adults exhibited a greater number of up-regulated immune-related genes, elevated phenoloxidase and prophenoloxidase activity, and higher hemocyte counts, particularly during early infection. Tracking macronutrient dynamics and associated gene expression showed that the NO group displayed up-regulation of more metabolic-related genes, which positively correlated with immune activity. These findings highlight a developmentally coordinated link between nutrition and immunity, contributing to an integrated understanding of nutritional and developmental immunology.

Early omnivory leaves a developmental imprint on insect immunity: adults emerging from omnivorous nymphs show stronger constitutive and inducible defenses, accompanied by elevated metabolic activity.