Knockdown of the juvenile hormone acid O-methyltransferase gene impairs development of Agrotis ipsilon (Lepidoptera: Noctuidae)

Abstract

In insects, the juvenile hormone (JH) acid O-methyltransferase (JHAMT) is required for JH synthesis. Agrotis ipsilon is known as the black cutworm and is a key agricultural pest; however, its JHAMT gene remains uncharacterized. Herein, we identified and functionally characterized A. ipsilon JHAMT (designated AiJHAMT). AiJHAMT consisted of three introns and four exons, and encoded the AiJHAMT protein, which contained 271 amino acid residues. AiJHAMT displayed features typical of other insect JHAMTs and shared a close phylogenetic relationship with a Mythimna separata ortholog. Experimentally, in A. ipsilon larvae, oral double-stranded RNA (dsRNA) delivery significantly reduced AiJHAMT mRNA levels and JH titers. AiJHAMT knockdown also affected larval growth, sharply reducing larval body length and weight and AiJHAMT-silenced larvae survival rates decreased to 46.5%. Moreover, AiJHAMT silencing reduced pupation rates by 61.8%. Therefore, AiJHAMT is vital for A. ipsilon growth, development, and survival and may be used for RNA interference (RNAi)-based pest strategies.