# Host-Affected Body Coloration Dynamics in Perina nuda Larvae: A Quantitative Analysis of Color Variations and Endogenous Plant Influences

## TL;DR

This study shows how chemicals in banyan tree leaves affect the body color of Perina nuda larvae, which could help in managing these pests.

## Contribution

Quantitative analysis reveals that chlorophyll-b in host plants strongly influences larval coloration, offering new insights into pest-host interactions.

## Key findings

- Chlorophyll-b in host leaves is the dominant driver of larval body coloration, particularly in the dorsal thorax and abdomen.
- Flavonoids show subthreshold significance in darkening the dorsal mid-line of larvae.
- Leaf and larval coloration are weakly but significantly linked in specific larval regions.

## Abstract

Perina nuda larvae are serious pests of banyan trees in southern China, causing significant damage. This study used computer technology to accurately measure color changes in different parts of the larvae as they fed on various banyan species. Additionally, we analyzed the chlorophyll, carotenoid, soluble sugar, soluble protein, tannin, flavonoid, and total phenol contents in the leaves to understand their effects on larval coloration. Results showed that chlorophyll-b in the leaves had the most significant impact on the body coloration of larvae, making certain body parts lighter or darker. Flavonoids also influenced coloration but to a lesser extent. Understanding how host plant chemicals influence larval coloration may provide insights that could inform the development of targeted pest management strategies, thereby contributing to the health and sustainability of banyan trees and their ecosystems.

Insects’ body coloration may be indirectly influenced by their host plants. Perina nuda (Lepidoptera: Lymantriidae), commonly known as the Banyan Tussock Moth and a serious pest of banyan trees (Ficus spp.) in southern China, exhibits light body coloration during its first- to third-instar stages, with its coloration progressively darkening as it matures, but little is known of the relationship between larval body coloration and host plants. To address this gap, we examined the R (red), G (green), B (blue), and L (lightness) values of the head, dorsal thorax and abdomen, stripe, dorsal mid-line, and tail of larvae fed on different hosts and host endogenous substance by using quantitative image analysis and chemical determination. Our results revealed that larval body coloration exhibited conserved ontogenetic patterns but varied significantly with host species, developmental age, and anatomical region. Redundancy analysis identified chlorophyll-b as the dominant driver, strongly associating with dorsal thorax–abdomen pigmentation. Flavonoids exhibited subthreshold significance, correlating with darker dorsal mid-line coloration, while nutrients (sugars, proteins) showed negligible effects. Linear regression revealed weak but significant links between leaf and larval body coloration in specific body regions. These findings demonstrate that host plant endogenous substances play a critical role in shaping larval body coloration. This study provides a foundation for understanding the ecological and biochemical mechanisms underlying insect pigmentation, with implications for adaptive evolution and pest management strategies.