# Identification and Expression Profiles of Chemosensory Genes in the Antennal Transcriptome of Protaetia brevitarsis (Coleoptera: Scarabaeidae)

## TL;DR

This study identifies and analyzes chemosensory genes in the antennae of Protaetia brevitarsis, a pest beetle, to better understand its sense of smell and improve pest control methods.

## Contribution

The study provides the first comprehensive characterization of chemosensory genes in P. brevitarsis and reveals sex-specific expression patterns.

## Key findings

- 117 chemosensory-related genes were identified, including odorant receptors, ionotropic receptors, and odorant-binding proteins.
- Sexual dimorphism was observed in the expression of certain odorant receptor genes, suggesting roles in sex-specific behaviors.
- Five PbreOBP genes and twenty-three ORs were found to be enriched in the antennae, highlighting their potential in olfactory functions.

## Abstract

Protaetia brevitarsis, a prominent agroforestry pest widely found in East Asia, causes substantial economic losses through the direct feeding of adults on commercially valuable fruits, such as apples and grapes. Current management strategies depend predominantly on the use of chemical pesticides and physical trapping methods. However, prolonged pesticide application promotes insecticide resistance and environmental contamination, whereas conventional trapping techniques suffer from limited efficacy as they lack optimized olfactory attractants. Given the significance of the olfactory system in mediating essential behaviors, including host localization, mating, and oviposition, deciphering the chemosensory mechanisms of P. brevitarsis could help develop eco-friendly pest-control approaches. In this study, we comprehensively characterized the chemosensory-related gene repertoire of P. brevitarsis and elucidated its phylogenetic relationships and tissue-specific expression patterns. These findings provide molecular insights that will guide future functional investigations and facilitate the development of olfactory disruption-based precise pest-control technologies.

Chemosensory systems play a pivotal role in insect survival and reproduction by mediating the detection of volatile organic compounds in the environment. Protaetia brevitarsis (Coleoptera: Scarabaeidae), a phytophagous pest widely distributed across East Asia, poses a significant threat to agro-horticultural systems through crop damage. We conducted antennal transcriptome sequencing of adult beetles and identified 117 chemosensory-related genes, including 66 odorant receptors (ORs), 20 ionotropic receptors, 10 gustatory receptors, 13 odorant-binding proteins (OBPs), four chemosensory proteins, and four sensory neuron membrane proteins. Tissue-specific expression profiling revealed the antennal enrichment of five PbreOBP genes and twenty-three ORs. Notably, sexual dimorphism was observed in OR expression patterns. PbreOR1/6/17/18/21/22/30/32 exhibited male-biased antennal expression, whereas PbreOR25/26/29/38/41/44/61 demonstrated female-biased antennal expression, indicating their potential involvement in sex-specific behaviors, such as pheromone detection and oviposition site selection. A comprehensive description of the antenna chemosensory-related genes of P. brevitarsis has deepened our understanding of the olfactory mechanisms in coleopteran insects. This study also provides a basis for understanding the molecular mechanisms underlying olfaction in P. brevitarsis.