Identification and characterization of three juvenile hormone genes from Bactrocera dorsalis (Diptera: Tephritidae)

Juvenile hormone (JH) plays an important role in regulating growth, development, and reproduction of insects. Three key enzymes, namely, JH esterase (JHE), JH epoxide hydrolase (JHEH), and JH diol kinase (JHDK), are involved in JH degradation. In this study, we identified the full-length cDNAs of the 3 genes BdJHEH2, BdJHEH3, and BdJHDK encoding JHEH and JHDK from the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). We used quantitative real-time polymerase chain reaction to investigate mRNA expression profiles of these 3 genes in various development stages and tissues, and in response to both 20-hydroxyecdysone (20E) and starvation. Both BdJHEH2 and BdJHDK were highly expressed during the larvalpupal transition, whereas BdJHEH3 was mainly expressed in the early 3rd instars. All 3 genes were highly expressed in 7-d-old and 10-d-old adults, but exhibited sex-specific expression patterns. BdJHEH2 was highly expressed in fat body, whereas BdJHEH3 and BdJHDK were most abundant in Malpighian tubules. In response to 20E exposure, the 3 genes were significantly up-regulated at various time points compared with the control. However, the transcript levels of BdJHDK decreased significantly during the initial exposure to 20E. After starvation treatment, expression of BdJHEH2 and BdJHEH3 significantly decreased, whereas BdJHDK was up-regulated. No significant change was observed after feeding resumption. These 3 genes have distinct roles in regulating growth and development of B. dorsalis.