Transcriptome characterization and gene expression analysis related to sexual dimorphism in the ghost moth, Thitarodes pui, a host of Ophiocordyceps sinensis.

Thitarodes pui is one of the host species of the Chinese caterpillar fungus Ophiocordyceps sinensis as a traditional Chinese medicine with economic and medical importance. The pupal and adult stages of T. pui are sexually dimorphic. In order to elucidate the molecular mechanisms involved in the sexually dimorphic development of T. pui, we compared the transcriptomes of female and male pupae and adults. We obtained 15,881,734, 16,962,086, 17,514,743, and 17,770,904 clean reads from female pupae, male pupae, female adults, and male adults, respectively. The reads obtained from the four samples were pooled and assembled into 65,165 unigenes, 23,597 of which were annotated. Candidate genes involved in sexual development were identified and analysed. Gene expression analysis revealed that 1406 genes were differentially expressed in male and female pupae, 448 of which were up-regulated in males and 958 were up-regulated in females. A total of 2025 genes were differentially expressed in male and females adults, 1304 of which were up-regulated in males and 721 were up-regulated in females. The functional enrichment of the differentially expressed genes indicated that reproduction and cuticle synthesis were regulated differently between the sexes. The transcriptome data obtained provide significant information regarding the genes involved in sexually dimorphic development, which will improve our understanding of the molecular mechanisms related to sexual dimorphism and helpful for the moth mass rearing which would provide enough host insects for the sustainable utilization of O. sinensis.