Antennal transcriptome sequencing and identification of candidate chemoreceptor proteins from an invasive pest, the American palm weevil, Rhynchophorus palmarum

Francisco Gonzalez,Emmanuelle Jacquin-Joly,Abdulaziz S Alqarni,William B Walker,Arnab Pain,Sara Mfarrej,Jernej Jakše,Binu Antony,Mohammed Ali Al-Saleh,Qingtian Guan,Nicolas Montagné,Jibin Johny

doi:10.1038/s41598-021-87348-y

Abstract

For decades, the American palm weevil (APW), Rhynchophorus palmarum, has been a threat to coconut and oil palm production in the Americas. It has recently spread towards North America, endangering ornamental palms, and the expanding date palm production. Its behavior presents several parallelisms with a closely related species, R. ferrugineus, the red palm weevil (RPW), which is the biggest threat to palms in Asia and Europe. For both species, semiochemicals have been used for management. However, their control is far from complete. We generated an adult antennal transcriptome from APW and annotated chemosensory related gene families to obtain a better understanding of these species' olfaction mechanism. We identified unigenes encoding 37 odorant-binding proteins (OBPs), ten chemosensory proteins (CSPs), four sensory neuron membrane proteins (SNMPs), seven gustatory receptors (GRs), 63 odorant receptors (ORs), and 28 ionotropic receptors (IRs). Noticeably, we find out the R. ferrugineus pheromone-binding protein and pheromone receptor orthologs from R. palmarum. Candidate genes identified and annotated in this study allow us to compare these palm weevils' chemosensory gene sets. Most importantly, this study provides the foundation for functional studies that could materialize as novel pest management strategies.

Highlights

Insects live embedded in a chemical environment, in which their survival depends on the proper understanding of those chemical signals
olfactory sensory neurons (OSNs) activation requires another set of proteins known as sensory neuron membrane proteins (SNMPs)
A second step forward for the management of both the red palm weevil (RPW) and the American Palm Weevil (APW) came with demonstrating a synergism between the pheromone blend of each species and the kairomone ethyl acetate the existence of several other kairomones that signal the suitability of the host

Summary

Introduction

Insects live embedded in a chemical environment, in which their survival depends on the proper understanding of those chemical signals. Detection of non-volatile chemicals (tastants) by sensory neurons of gustatory sensilla is mediated by specialized proteins known as gustatory receptors (GRs). These receptors are seven-transmembrane domain proteins and, together with the ORs, form the large chemoreceptor superfamily[12]. A second step forward for the management of both the RPW and the APW came with demonstrating a synergism between the pheromone blend of each species and the kairomone ethyl acetate the existence of several other kairomones that signal the suitability of the host This further accentuated the importance of the sense of smell for aggregation and host selection for these s pecies[32,37,38,39]. In the case of R. palmarum, the only proteins identified so far are RpalOBP2 and RpalOBP444

Methods

Results

Conclusion