Putative Chemosensory Receptors of the Codling Moth, Cydia pomonella, Identified by Antennal Transcriptome Analysis

Jonas M Bengtsson,Rickard Ignell,Federica Trona,Peter Witzgall,Gianfranco Anfora,Emmanuelle Jacquin-Joly,Nicolas Montagné,Hiroaki Matsunami

doi:10.1371/journal.pone.0031620

Jonas M Bengtsson, Rickard Ignell + Show 6 more

Open Access

https://doi.org/10.1371/journal.pone.0031620

Copy DOI

Abstract

The codling moth, Cydia pomonella, is an important fruit pest worldwide. As nocturnal animals, adults depend to a large extent on olfactory cues for detection of food and mates, and, for females, oviposition sites. In insects, odor detection is mediated by odorant receptors (ORs) and ionotropic receptors (IRs), which ensure the specificity of the olfactory sensory neuron responses. In this study, our aim was to identify chemosensory receptors in the codling moth as a means to uncover new targets for behavioral interference. Using next-generation sequencing techniques, we identified a total of 43 candidate ORs, one gustatory receptor and 15 IRs in the antennal transcriptome. Through Blast and sequence similarity analyses we annotated the insect obligatory co-receptor ORco, five genes clustering in a conserved clade containing sex pheromone receptors, one homolog of the Bombyx mori female-enriched receptor BmorOR30 (but no homologs of the other B. mori female-enriched receptors) and one gene clustering in the sugar receptor family. Among the candidate IRs, we identified homologs of the two highly conserved co-receptors IR8a and IR25a, and one homolog of an IR involved in phenylethyl amine detection in Drosophila. Our results open for functional characterization of the chemosensory receptors of C. pomonella, with potential for new or refined applications of semiochemicals for control of this pest insect.

Highlights

Insects employ olfaction for several vital tasks, such as the search for food and mates, and location of suitable oviposition sites by females [1]
Subsets of olfactory sensory neurons (OSNs) express proteins from the gustatory receptor (GR) family [5], which are structurally related to odorant receptors (ORs), or ionotropic receptors (IRs), which are related to ionotropic glutamate receptors [6]
Sequencing and identification of OR and IR genes A total of 464307 reads were obtained for the male sample and 467771 reads for the female sample

Summary

Introduction

Insects employ olfaction for several vital tasks, such as the search for food and mates, and location of suitable oviposition sites by females [1]. Several families of transmembrane proteins appear to form binding sites for odorant molecules at the membrane surface of OSNs, of which the odorant receptor (OR) family is the most widely expressed [2]. OR proteins of insects have seven transmembrane domains, but have the N-terminus on the inside of the cell membrane, i.e. an inverted topology compared to vertebrate ORs, to which they are unrelated [3]. To function, they require the presence of a conserved co-receptor named ORco [3,4]. Subsets of OSNs express proteins from the gustatory receptor (GR) family [5], which are structurally related to ORs, or ionotropic receptors (IRs), which are related to ionotropic glutamate receptors [6]

Objectives

Methods

Results

Conclusion