# Odorant-binding proteins (OBPs) in Ceratitis capitata Wiedemann (Diptera: Tephritidae): integrative analysis of a multigene family

## TL;DR

This study identifies and classifies odorant-binding proteins in the Mediterranean fruit fly, offering insights into its olfactory system and potential for pest control.

## Contribution

The study provides the most comprehensive OBP homologation in medfly using integrative genomic and transcriptomic data.

## Key findings

- A homologized repertoire of 48 CcapOBPs was consolidated through comparative genomic and transcriptomic analyses.
- RT-PCR confirmed expression of 21 CcapObps in male heads, showing consistency across data sources.
- Phylogenetic analysis revealed clustering patterns and gene duplications specific to C. capitata.

## Abstract

The Mediterranean fruit fly (Ceratitis capitata Wiedemann, medfly) is a highly invasive agricultural pest with a considerable threat to global fruit production. Its olfactory system, mediated by odorant-binding proteins (OBPs), plays a fundamental role in key behaviors such as host localization, mate recognition, and oviposition site selection. This study presents a comprehensive homologation and systematic reclassification of CcapOBPs through comparative genomic analyses with the model organism Drosophila melanogaster Meigen and 8 Tephritidae species (tribes Dacini, Toxotrypanini, and Trypetini), supported by Bayesian phylogenetic inference. By integrating 2 genome assemblies (Ccap_2.1 and EGII-3.2.1), additional GenBank entries, a de novo head transcriptome from sexually mature wild males, and comparative analyses with D. melanogaster orthologs, we consolidated 156 candidate sequences into a homologized repertoire of 48 CcapOBPs. RT-PCR validation of 21 representative CcapObps confirmed their expression in male heads and highlighted how the de novo transcriptome recovered genes missing from individual genome assemblies, demonstrating consistency across all data sources. Phylogenetic reconstruction of CcapOBP and tephritid species revealed clustering patterns consistent with the established evolutionary relationships within the family, enabling the identification of ortholog genes, lineage-specific diversification events, gene duplications, expansions in C. capitata. However, limitations were identified in datasets for the other fruit fly species, and the need for nomenclature adjustments based on chromosomal localization. This study represents the most comprehensive OBP homologation in medfly to date, providing a robust framework for understanding the molecular evolution of chemosensory systems in Tephritidae and supporting the development of species-specific and environmentally sustainable pest management strategies.