Olfactory Reception of Host Alarm Pheromone Component by the Odorant-Binding Proteins in the Samurai Wasp, Trissolcus japonicus (Hymenoptera: Scelionidae).

Jinping Zhang,Guohua Chen,Feng Zhang,K B Rebijith,Rui Tang,Yongzhi Zhong,Fengqi Li

doi:10.3389/fphys.2020.01058

Abstract

The samurai wasp, Trissolcus japonicus, is the predominant egg parasitoid of the brown marmorated stink bug, Halyomorpha halys, in its native range in China. (E)-2-Decenal is a major component of the alarm pheromone of H. halys, an important invasive insect pest with significant economic importance. T. japonicus can be strongly repelled by (E)-2-decenal, and thus its host location efficiency would be reduced in the field. Better understanding on the molecular basis of olfactory reception of this host alarm pheromone component by T. japonicus may provide opportunities to develop novel approaches to enhance biological control efficacy of the parasitoid against H. halys. We identified six Odorant Binding Proteins (OBPs) from T. japonicus by transcriptome sequencing, within which three classical OBPs were expressed in a heterologous expression system with E. coli, harvested, and then challenged with (E)-2-decenal in binding assay experiments. TjapOBP2 showed the highest binding ability to (E)-2-decenal, compared to TjapOBP1 and TjapOBP3. Our results unambiguously suggest that TjapOBP2 would play an important role in discriminating (E)-2-decenal and could be a possible target for further intervention in the parasitoid–host system.

Highlights

Olfaction plays a crucial role in insects to sense biologically meaningful chemical signals in their surroundings for food, a mate, oviposition, prey, or enemies (Schneider, 1969; Bruyne and Baker, 2008; Conchou et al, 2019)
A total of 19 962 genes was annotated to 50 classification of Gene Ontology (GO) function and categorized by biological process, cellular component, and molecular function (Supplementary Figure S1)
For the first time, we identified six TjapOBPs, and three of them were all classical odorant-binding proteins (OBPs) with 6 cysteine residues (Cys)

Summary

Introduction

Olfaction plays a crucial role in insects to sense biologically meaningful chemical signals in their surroundings for food, a mate, oviposition, prey, or enemies (Schneider, 1969; Bruyne and Baker, 2008; Conchou et al, 2019). The extensive use of broad-spectrum insecticides may have adverse effects such as environmental pollution and residual problems for the health of farmers and consumers (Leong et al, 2020), increased chances of insecticide resistance (Haye et al, 2015), and outbreak of secondary pests (Leskey et al, 2012). To overcome these shortcomings of chemical control, it is very important to develop an alternative, safe, and eco-friendly method based on integrated pest management (IPM) practices, such as biological control, for sustainable management of BMSB

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Results

Conclusion