RNAi-mediated knockdown of juvenile hormone acid O-methyltransferase disrupts larval development in the oriental fruit fly, Bactrocera dorsalis (Hendel)

Abstract

The oriental fruit fly, Bactrocera dorsalis (Hendel), is a notoriously agricultural pest that causes serious economic losses to fruits and vegetables. Widespread insecticide resistance in B. dorsalis is a major obstacle in successful control. Therefore, new pest control strategies, such as those targeting specific genes that can block pest development, are urgently needed. In the current study, the function of JHAMT in B. dorsalis was systematically investigated. A methyltransferase gene in B. dorsalis (BdJHAMT) that is homologous to JHAMT of Drosophila melanogaster was cloned firstly. The subsequently spatiotemporal expression analysis indicated that BdJHAMT mRNA was continuously present in the larval stage, declined sharply immediately before pupation, and then increased in the adult. Subcellular localization showed that BdJHAMT was localized in the adult corpora allata and larval intestinal wall cells. The JH III titer in B. dorsalis was closely related to the transcription level of BdJHAMT in different developmental stages. The dsBdJHAMT feeding-based RNAi resulted in a greatly decreased JH III titer that disrupted fly development. The slow growth caused by BdJHAMT silencing was partially rescued by application of the JH mimic, methoprene. These results demonstrated that BdJHAMT was crucial for JH biosynthesis and thus regulated larval development in B. dorsalis, indicating it may serve as a prospective target for the development of novel control strategies against this pest.