# Genome-Wide Identification and Comparative Characterization of Chemosensory Gene Families in Two Phthorimaea Pests

## TL;DR

This study identifies and compares chemosensory genes in two pest species, revealing sex- and tissue-specific expression patterns that could help in developing pest control strategies.

## Contribution

The study provides a comprehensive identification and comparative analysis of chemosensory gene families in two Phthorimaea pest species, with insights into gene expression patterns.

## Key findings

- 47 OBPs, 26 CSPs, and 2 SNMPs were identified in Phthorimaea operculella.
- Sex-biased expression was observed in antennae and reproductive tissues, with specific genes upregulated in females and males.
- Candidate genes for olfaction and reproduction-related behaviors were identified, offering targets for pest management.

## Abstract

The potato tuber moth (Phthorimaea operculella) and the tomato leafminer (Phthorimaea absoluta) are major solanaceous-crop pests. These insects depend on chemosensory genes to detect odors and select hosts and oviposition sites. In this study, we identified three important chemosensory gene families (OBPs, CSPs, and SNMPs) from the genomes of both species and analyzed their evolutionary relationships. Using RNA-seq data from P. operculella, we further examined gene expression patterns across tissues and sexes. Several genes showed strong tissue- and sex-biased expression, especially in antennae and reproductive organs, suggesting roles in olfaction and reproduction-related behaviors. This work provides a useful gene resource and candidate targets for future functional studies and behavior-based pest management.

Insects rely on their olfactory systems for host finding, mate choice, and oviposition. These odor-guided behaviors are mediated by the peripheral chemosensory system. The solanaceous pests Phthorimaea operculella and Phthorimaea absoluta cause severe damage to solanaceous crops worldwide. In this study, we aimed to elucidate the olfactory molecular mechanisms of these two pests. We first screened and identified odorant-binding proteins (OBPs), chemosensory proteins (CSPs), and sensory neuron membrane proteins (SNMPs) from the genomes of P. operculella and P. absoluta. We then used RNA sequencing to characterize the tissue expression profiles of OBPs, CSPs, and SNMPs in P. operculella across developmental stages and adult chemosensory organs. From P. operculella, 47 OBPs, 26 CSPs, and 2 SNMPs were identified, and from P. absoluta, 39 OBPs, 24 CSPs, and 2 SNMPs were identified. RNA-seq-based expression profiling in P. operculella was used to resolve sex-biased deployment in antennae: DESeq2 analysis (|log2FC| > 1, FDR < 0.05) identified 24 OBPs and four CSPs with significant sexual dimorphism, with 14 OBPs and four CSPs upregulated in female antennae (FAn) and 10 OBPs and one CSP, together with SNMP2, upregulated in male antennae (MAn). In reproductive tissues (FOv vs. MGe), three OBPs and one CSP were enriched in the female ovipositor (FOv), whereas six OBPs and five CSPs were enriched in male genitalia (MGe), and no SNMPs met the differential-expression threshold. These candidate genes provide molecular entry points for functional studies and for developing behavior-based, environmentally compatible management strategies for P. operculella and P. absoluta.