**5. Conclusions**

In conclusion, we assembled the first transcriptome for *D. longicaudata* using transcriptome sequencing and identified 43 OBPs, 69 CSPs, 60 GRs, 689 ORs, 26 IRs, and 14 SNMPs. Further, 9 OBPs, 13 CSPs, 3 GRs, 4IRs, 25 ORs, and 4 SNMPs were differentially expressed in the insects in response to fruit flies with different scents. Our findings provide a basis towards understanding the molecular mechanisms of *D. longicaudata* in the detection of chemosensory cues. Additionally, the sequences including olfactory genes, noncoding genes, and miRNAs identified in this study can be used in the future and benefit other researchers in this field.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2073-4425/11/2/144/s1, Figure S1: Multiple sequence alignment of OBP sequences identified in this study. It showed the conserved six Cys (C1~C6) in these sequences (highlighted in yellow and marked with \*). Table S1: miRNA precursors identified in the parasitoid wasp transcriptome. Table S2: Expression profile of transcripts encoding olfactory proteins. Table S3: OBP and CSP sequences for the phylogenetic analysis. Table S4: Differentially expressed transcripts in the parasitoid wasps of fruit flies fed with different fruits.

**Author Contributions:** Conceptualization, H.Z. and W.L.; methodology, L.T. and J.L.; software, Y.Y.; validation, L.T., J.L. and H.Z.; formal analysis, L.T.; investigation, H.Z.; resources, J.L. and L.L.; data curation, J.L. and Y.Y.; writing—original draft preparation, L.T. and J.L.; writing—review and editing, H.Z. and W.L.; visualization, J.L.; supervision, H.Z.; project administration, H.Z.; funding acquisition, H.Z. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China (31560531) and Guangxi Innovation-driven Projects (AA17202017-2).

**Acknowledgments:** We acknowledge all the members from the Key Laboratory of Intergrated Pest Management on Tropical Crops, Ministry of Agriculture, Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences for their helpful discussions and kindness opinions.

**Conflicts of Interest:** The authors declare no conflict of interest.
