Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) is an effective ectoparasitoid of pine sawyer beetle Monochamus alternatus Hope (Coleoptera: Cerambycidae) which is the major median insect for transmission of pine wood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle (Aphelenchida: Parasitaphelenchidae). A sensitive and acute olfactory system is extremely essential for newly hatched larva of D. helophoroides to forage for a host. Therefore, we established the transcriptome of newly hatched D. helophoroides larvae and characterized the expression profiles of olfactory genes. We identified 20 transcripts encoding putative odorant binding proteins (OBPs), 11 putative chemosensory proteins (CSPs), 9 putative odorant receptors (ORs), 11 putative ionotropic receptors (IRs), 7 putative gustatory receptors (GRs) and 4 putative sensory neuron membrane proteins (SNMPs) olfactory genes from the transcriptome of newly hatched D. helophoroides larvae. According to the phylogenetic analysis, 3 OBPs (DhelOBP6, DhelOBP14 and DhelOBP19), 1 CSP (DhelCSP11), 1 OR (DhelOrco1), 3 IRs (DhelIR3, DhelIR6 and DhelIR8), 3 GRs (DhelGR2, DhelGR4 and DhelGR5) and 2 SNMPs (DhelSNMP1 and DhelSNMP3) had high similarities with reported Coleopteran species. The highest expressed olfactory gene was DhelCSP3, followed by DhelOBP8 and DhelCSP2. The expression levels of the majority of OR, IR, GR and SNMP genes were low. These results indicate that CSPs and OBPs may play important roles in the olfactory recognition process in newly hatched D. helophoroides larvae. The findings from the present study are helpful in unraveling the profound mystery between D. helophoroides and M. alternatus, as well as improving the parasitism efficiency of D. helophoroides larvae.

中文翻译：

---

通过转录组分析鉴定鞘翅目外寄生物 Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) 新孵化幼虫的假定嗅觉基因

Dastarcus helophoroides (Fairmaire) (鞘翅目：Bothrideridae) 是松木甲虫 Monochamus alternatus Hope (Coleoptera: Cerambycidae) 的一种有效外寄生物，它是传播松材线虫、松材线虫 (Bursaphelenchus xylophilus) 的主要中位昆虫 (Steiner et Buhren寄生虫科）。灵敏而敏锐的嗅觉系统对于 D. helophoroides 新孵化的幼虫为宿主觅食是极其重要的。因此，我们建立了新孵化的 D. helophoroides 幼虫的转录组并表征了嗅觉基因的表达谱。我们鉴定了 20 个编码推定气味结合蛋白 (OBP)、11 个推定化学感应蛋白 (CSP)、9 个推定气味受体 (OR)、11 个推定离子型受体 (IR) 的转录本，来自新孵化的 D. helophoroides 幼虫转录组的 7 个假定的味觉受体 (GRs) 和 4 个假定的感觉神经元膜蛋白 (SNMPs) 嗅觉基因。根据系统发育分析，3个OBPs（DhelOBP6、DhelOBP14和DhelOBP19）、1个CSP（DhelCSP11）、1个OR（DhelOrco1）、3个IRs（DhelIR3、DhelIR6和DhelIR8）、3个GRs（DhelGR2、Dhel2、SNMP和（DhelSNMP1 和 DhelSNMP3）与报道的鞘翅目物种具有高度相似性。最高表达的嗅觉基因是 DhelCSP3，其次是 DhelOBP8 和 DhelCSP2。大多数OR、IR、GR和SNMP基因的表达水平较低。这些结果表明 CSPs 和 OBPs 可能在新孵化的 D. helophoroides 幼虫的嗅觉识别过程中发挥重要作用。