DOI: 10.5061/dryad.9zw3r22tz
title: Larval diet quality affects allocation tradeoffs in both larvae and adult stages of a moth

description: Resource availability during development is a key driver of physiological
 trade-offs, yet how early nutritional environments shape allocation
 strategies across life stages remains unclear. During development, insect
 larvae must balance investment between growth and immune defense, but the
 downstream consequences of these allocation decisions for adult traits are
 not well understood. We examined how larval diet quality influences
 tradeoffs among immune investment, growth, and adult morphology in the
 hawkmoth Hyles lineata (Sphingidae). Larvae reared on higher-quality diets
 exhibited enhanced immune responses, along with faster growth and greater
 body mass. However, immune investment varied by component: total hemocyte
 count (THC) increased under both medium- and high-quality diets, while
 phenoloxidase (PO) activity was elevated only under high-quality diet
 conditions, indicating a higher nutritional threshold. Interestingly, body
 mass did not predict hemocyte count, and a negative relationship emerged
 between body mass and PO activity under high-quality diets, suggesting
 context-dependent allocation trade-offs. Larval diet had lasting effects
 on adult morphology: higher-quality diets led to increased thorax and
 abdomen sizes, while head size remained unchanged. Interestingly, a
 negative correlation emerged between larval immune investment and adult
 body structure, where elevated larval PO activity was associated with
 reduced adult thorax and abdomen sizes, revealing a cross-stage trade-off
 on high-quality diets. More interestingly, a mild larval stress altered
 these patterns in a diet-dependent manner. On the low-quality diet,
 stressed larvae developed larger thorax and abdomen than controls, whereas
 on the high-quality diet, stress activation reduced or erased size gains.
 Collectively, our results demonstrate that the larval nutritional
 environment shapes allocation strategies across ontogeny, with hidden
 tradeoffs between growth and immunity leaving enduring imprints on adult
 phenotype.
description: # Larval diet quality affects allocation tradeoffs in both larvae and
 adult stages of a moth Dataset DOI:
 [10.5061/dryad.9zw3r22tz](10.5061/dryad.9zw3r22tz) ## Description of the
 data and file structure File 1: Diet quality, weight gain, THC, and PO
 (Diet_quality__weight_gain__THC_and_PO.xlsx)- Diet quality is represented
 as (1) 60% diet, (2) 80% diet, or (3) 100% diet (standard rearing diet).
 In the 60% and 80% diets, the nutritional components of the standard
 (100%) diet were reduced proportionally, and the remaining volume was
 filled with 50% cellulose (Alphacel, ICN, Aurora, OH, USA) to maintain
 bulk without adding nutritional value. The total hemocyte count and
 phenoloxidase activity (PO) are measured from the 16-day-old larvae.
 Missing data represented as n/a.  File 2: Stressed vs control
 (Stressed_vs_control_Calories)- To assess how larval-stage stress
 influences energy allocation and subsequent adult body size, we reared
 larvae under our three dietary treatments and divided them into two
 groups- 1) the control group consisted of unstressed larvae, and 2) the
 treatment group consisted of stressed larvae which received a simulated
 immune challenge that mimicked parasitoid oviposition. This was achieved
 by gently pricking the lateral body of the larvae with a fine needle to
 replicate the mechanical damage typically caused by parasitoid
 oviposition. After the challenge, all larvae were maintained under
 identical rearing conditions and monitored daily through pupation and
 adult emergence. Adults were collected within 12 hours of eclosion and
 euthanized by freezing. To estimate body size, we measured dry body mass
 after drying individuals at 50°C for 44 hours, then weighing them to the
 nearest 0.01 mg using a microbalance.