Transcriptome characterization analysis and molecular profiles of obligatory diapause induction of the Chinese citrus fruit fly, Bactrocera minax (Diptera: Tephritidae)

The Chinese citrus fruit fly, Bactrocera minax, is a devastating citrus pest in China, Bhutan and India. It will enter obligatory pupal diapause in each generation at specific stage, while little is known about the course and the molecular mechanisms of diapause induction. To gain insight into possible mechanisms of obligatory pupal diapause induction, high-throughput RNA-seq data were generated from second-instar larvae (2L), third-instar larvae (3L) and pupal (P, one week after pupating). A total of 116,402 unigenes were assembled and researched against public databases, and 54,781 unigenes matched to proteins in the NCBI database using the BLAST search. Three pairwise comparisons were performed, and significantly differentially regulated transcripts were identified. Several differentially expressed genes (DEGs) expression patterns revealed that those highly or lowly expressed genes in pupal stage were predicted to be involved in diapause induction. Moreover, GO function and KEGG pathway analysis were performed on all DEGs and showed that 20-hydroxyecdysone (20E) biosynthesis, insulin signaling pathway, FoxO signaling pathway, cell cycle and metabolism pathway may be related to the obligatory diapause of the Chinese citrus fruit fly. This study provides valuable information about the Chinese citrus fruit fly transcriptome for future gene function research, and contributes to the in-depth elucidation of the molecular regulation mechanism of insect obligatory diapause induction.