# Transcriptome Analysis and Identification of Chemosensory Genes in the Galleria mellonella Larvae

## TL;DR

This study identifies 25 chemosensory genes in Galleria mellonella larvae, revealing their expression patterns and potential roles in feeding behavior and pest control.

## Contribution

The study expands the known chemosensory gene repertoire in Galleria mellonella and identifies two novel genes with larval-specific expression.

## Key findings

- 25 chemosensory genes were identified across six functional classes in Galleria mellonella larvae.
- Most chemosensory genes showed adult antennal-biased expression, while two genes (OBP22 and SNMP3) were highly expressed in larval heads.
- Differential expression analysis revealed nine putative chemosensory genes with potential functional roles in larval tissues.

## Abstract

Lepidopteran larvae, the primary plant-feeding and damaging stage, have received less research focus than adult chemosensory mechanisms. The greater wax moth Galleria mellonella, a destructive pest in apiculture worldwide, causes substantial hive damage through larval consumption of wax combs and tunneling behavior. Through transcriptomic analysis of larval tissues, we characterized 25 chemosensory genes spanning six functional classes (OBPs, CSPs, ORs, GRs, IRs, and SNMPs). Transcriptional differences in chemosensory genes across head and body tissues were assessed through differential expression analysis and TPM-based quantification. Quantitative expression profiling of chemosensory genes in G. mellonella demonstrated distinct developmental regulation, with the majority exhibiting adult antennal-biased expression. Notably, two newly characterized genes (OBP22 and SNMP3) showed preferential expression in larval head tissues, suggesting specialized larval chemosensory functions. Our findings substantially expand the chemosensory gene repertoire in G. mellonella and identify molecular targets for understanding its feeding ecology, providing a foundation for future pest management strategies.

The greater wax moth Galleria mellonella (Lepidoptera: Galleriinae) represents a ubiquitous apicultural pest that poses significant threats to global beekeeping industries. The larvae damage honeybee colonies by consuming wax combs and tunneling through brood frames, consequently destroying critical hive infrastructure including brood-rearing areas, honey storage cells, and pollen reserves. Larval feeding behavior is critically dependent on chemosensory input for host recognition and food selection. In this study, we conducted a transcriptome analysis of larval heads and bodies in G. mellonella. We identified a total of 25 chemosensory genes: 9 odorant binding proteins (OBPs), 1 chemosensory protein (CSP), 5 odorant receptors (ORs), 4 gustatory receptors (GRs), 4 ionotropic receptors (IRs) and 2 sensory neuron membrane proteins (SNMPs). TPM normalization was employed to assess differential expression patterns of chemosensory genes between heads and bodies. Nine putative chemosensory genes were detected as differentially expressed, suggesting their potential functional roles. Subsequently, we quantified expression dynamics via reverse transcription quantitative PCR in major chemosensory tissues (larval heads, adult male and female antennae), revealing adult antennal-biased expression for most chemosensory genes in G. mellonella. Notably, two novel candidates (GmelOBP22 and GmelSNMP3) exhibited particularly high expression in larval heads, suggesting their crucial functional roles in larval development and survival. These findings enhance our understanding of the chemosensory mechanisms in G. mellonella larvae and establish a critical foundation for future functional investigations into its olfactory mechanisms.