Antennal transcriptome and expression analyses of olfactory genes in the sweetpotato weevil Cylas formicarius

Shu-Ying Bin,Xin-Hua Pu,Jin-Tian Lin,Meng-Qiu Qu,Zhong-Zhen Wu

doi:10.1038/s41598-017-11456-x

Shu-Ying Bin, Xin-Hua Pu + Show 3 more

Open Access

https://doi.org/10.1038/s41598-017-11456-x

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Abstract

The sweetpotato weevil, Cylas formicarius (Fabricius), is a serious pest of sweetpotato. Olfaction-based approaches, such as use of synthetic sex pheromones to monitor populations and the bait-and-kill method to eliminate males, have been applied successfully for population management of C. formicarius. However, the molecular basis of olfaction in C. formicarius remains unknown. In this study, we produced antennal transcriptomes from males and females of C. formicarius using high-throughput sequencing to identify gene families associated with odorant detection. A total of 54 odorant receptors (ORs), 11 gustatory receptors (GRs), 15 ionotropic receptors (IRs), 3 sensory neuron membrane proteins (SNMPs), 33 odorant binding proteins (OBPs), and 12 chemosensory proteins (CSPs) were identified. Tissue-specific expression patterns revealed that all 54 ORs and 11 antennal IRs, one SNMP, and three OBPs were primarily expressed in antennae, suggesting their putative roles in olfaction. Sex-specific expression patterns of these antenna-predominant genes suggest that they have potential functions in sexual behaviors. This study provides a framework for understanding olfaction in coleopterans as well as future strategies for controlling the sweetpotato weevil pest.

Highlights

Olfaction plays an essential role in the life cycle of insects that use a wide range of environmental chemical cues to locate and evaluate food, mates, and egg-laying sites as well as to avoid predators and other dangers
Annotation was conducted by BLASTx and BLASTn program with the E-value cut-off of 10−5, 31,532 (47.39%) unigenes were annotated by at least one of the databases: 30,003 (45.10%) unigenes were annotated by the NCBI-non-redundant protein sequence (Nr) database, 16,661 (25.04%) unigenes by the NCBI-Nt database, 22,720 (34.15%) by SwissPort, 9,010 (13.54%) by Gene Ontology (GO), 11,650 (17.51%) by the COG database, 22,812 (34.29%) by Kyoto Encyclopedia of Genes and Genomes (KEGG) (Fig. 1A)
BLASTx homology searches in the NCBI-Nr database showed that C. formicarius antennal transcriptomes had a best blast match to coleopteran sequences, primarily the mountain pine beetle D. ponderosae, (38.52%) and the red flour beetle T. castaneum (37.45%) (Fig. 1B)

Summary

Introduction

Olfaction plays an essential role in the life cycle of insects that use a wide range of environmental chemical cues to locate and evaluate food, mates, and egg-laying sites as well as to avoid predators and other dangers. Insect odor reception and signal transduction occurs in the dendritic membrane of olfactory sensory neurons (OSNs) in the antennae[2, 3]. Due to the life-history characteristics of C. formicarius, chemical control has typically been achieved with residual insecticides such as spinosad and azadirachtin. This management approach has led to control failures due to development of insecticide resistance[37]. The goal of the present study was to identify the genes involved in olfaction from the male and female antennae of C. formicarius using high-throughput sequencing.

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