Abstract
The black soldier fly, Hermetia illucens, is a cosmopolitan insect of the family Stratiomyidae (Diptera). Chemosensory genes encode proteins involved directly in the detection of odorants. In this study, we sequenced the antennal transcriptome of H. illucens adults to identify chemosensory genes. Putative unigenes encoding 27 odorant binding proteins (OBPs), five chemosensory proteins (CSPs), 70 odorant receptors (ORs), 25 ionotropic receptors (IRs), 10 gustatory receptors (GRs) and two sensory neuron membrane proteins (SNMPs) were identified. Tissue-specific expression profiles of the identified OBPs, CSPs and SNMPs were investigated using RT-PCR. Eight OBPs (HillOBP1-2, 9, 11-14, and 17), one CSP (HillCSP5) and one SNMP (HillSNMP1) were predominantly expressed in antennae. Further real-time quantitative PCR analyses revealed that the antennae-enriched unigenes also exhibited significant differences in expression between males and females. Among the sex-biased unigenes, six ORs showed female-biased expression, suggesting that these genes might participate in female-specific behaviors such as oviposition site searching. Sixteen ORs and two OBPs showed male-biased expression, indicating that they may play key roles in the detection of female sex pheromones. Our study is the first attempt to delineate the molecular basis of chemoreception in H. illucens. Our data provide useful information for comparative studies on the differentiation and evolution of Dipteran chemosensory gene families.
Highlights
Olfaction plays a crucial role in insect behaviors, such as foraging, mating, oviposition and avoiding predators (Leal, 2013)
The process of olfactory detection is mediated by a number of gene families including odorant-binding proteins (OBPs), chemosensory proteins (CSPs), sensory neuron membrane proteins (SNMPs), and olfactory receptors (ORs), ionotropic receptors (IRs)
ORs are responsible for the detection of odorants, whereas IRs are involved in sensing chemo, thermo- and hygro-sensory stimuli (Ai et al, 2010, 2013; Grosjean et al, 2011; Silbering et al, 2011; Kain et al, 2013; Su and Carlson, 2013; Koh et al, 2014; Chen et al, 2015; Stewart et al, 2015; Gorter et al, 2016; Hussain et al, 2016; Knecht et al, 2016, 2017; Ni et al, 2016)
Summary
Olfaction plays a crucial role in insect behaviors, such as foraging, mating, oviposition and avoiding predators (Leal, 2013). The process of olfactory detection is mediated by a number of gene families including odorant-binding proteins (OBPs), chemosensory proteins (CSPs), sensory neuron membrane proteins (SNMPs), and olfactory receptors (ORs), ionotropic receptors (IRs). OBPs and CSPs are thought to bind, solubilize and transport hydrophobic odorants across the aqueous lymph surrounding the olfactory sensory neurons (OSNs) on the sensilla of antennae (Wojtasek and Leal, 1999; Sandler et al, 2000; Xu et al, 2005; Gomez-Diaz et al, 2013). SNMPs may play important roles in pheromone sensing based on their expression on the dendritic membrane of pheromone sensitive neurons (Benton et al, 2007; Gomez-Diaz et al, 2016)
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