The odorant receptor co-receptor from the bed bug, Cimex lectularius L.

Immo A Hansen,John I Hammond,Alvaro Romero,Hitoshi Tsujimoto,Erika Y Monroy,Lisa L Drake,David P Price,Stacy D Rodriguez,William A Maio,Brittny N Blakely,Johannes Reisert

doi:10.1371/journal.pone.0113692

Abstract

Recently, the bed bug, Cimex lectularius L. has re-emerged as a serious and growing problem in many parts of the world. Presence of resistant bed bugs and the difficulty to eliminate them has renewed interest in alternative control tactics. Similar to other haematophagous arthropods, bed bugs rely on their olfactory system to detect semiochemicals in the environment. Previous studies have morphologically characterized olfactory organs of bed bugs’ antenna and have physiologically evaluated the responses of olfactory receptor neurons (ORNs) to host-derived chemicals. To date, odorant binding proteins (OBPs) and odorant receptors (ORs) associated with these olfaction processes have not been studied in bed bugs. Chemoreception in insects requires formation of heteromeric complexes of ORs and a universal OR coreceptor (Orco). Orco is the constant chain of every odorant receptor in insects and is critical for insect olfaction but does not directly bind to odorants. Orco agonists and antagonists have been suggested as high-value targets for the development of novel insect repellents. In this study, we have performed RNAseq of bed bug sensory organs and identified several odorant receptors as well as Orco. We characterized Orco expression and investigated the effect of chemicals targeting Orco on bed bug behavior and reproduction. We have identified partial cDNAs of six C. lectularius OBPs and 16 ORs. Full length bed bug Orco was cloned and sequenced. Orco is widely expressed in different parts of the bed bug including OR neurons and spermatozoa. Treatment of bed bugs with the agonist VUAA1 changed bed bug pheromone-induced aggregation behavior and inactivated spermatozoa. We have described and characterized for the first time OBPs, ORs and Orco in bed bugs. Given the importance of these molecules in chemoreception of this insect they are interesting targets for the development of novel insect behavior modifiers.

Highlights

Bed bugs, Cimex lectularius L. (Hemiptera: Cimicidae), are obligate hematophagous insects that have become a serious and growing global problem in the last decade [1,2,3,4,5]
Chronic blood loss and iron-deficiency anemia have been reported in people who have been continuously exposed to severe bed bug infestations [9,10,11]
Nine contigs were annotated as odorant receptors and one as an odorant binding protein using blast2GO

Summary

Introduction

Cimex lectularius L. (Hemiptera: Cimicidae), are obligate hematophagous insects that have become a serious and growing global problem in the last decade [1,2,3,4,5]. (Hemiptera: Cimicidae), are obligate hematophagous insects that have become a serious and growing global problem in the last decade [1,2,3,4,5]. They are not known to be vectors of human diseases, bed bugs have severe adverse effects on health and quality of life. Chronic blood loss and iron-deficiency anemia have been reported in people who have been continuously exposed to severe bed bug infestations [9,10,11]. The adverse effects of bed bugs on humans have led the Environmental Protection

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