Abstract: Bursicon is a neurohormone that regulates cuticle sclerotization (tanning and hardening) and the wing expansion processes in insects. Although bursicon genes have been well characterized from several insect species or predicted from insect genomes, bursicon and its genes in the diamondback moth (DBM), Plutella xylostella, remain poorly understood. In this study, two bursicon genes, Pxbursα and Pxbursβ (GenBank accession numbers: KF498645 and KF498646, respectively), were cloned from P. xylostella with the fulllength cDNA of 537 bp and 360 bp, respectively. The nucleotide sequence identities of Pxbursα and Pxbursβ with the bursicon genes from other insect species range from 51% to 68%, and 37% to 57%, respectively. Based on qRT-PCR results, we found that bursicon genes were expressed at a higher level in pupae, but at lower levels in larvae and adults. When the 4th-instar larvae were fed with double-stranded RNA of Pxbursα, the expression of Pxbursα in pupae subsequently declined significantly. Thus, the development of pupae was seriously delayed, and pupae died before eclosion. We inferred that higher level expression of Pxburs genes in pupae might play a key role in the metamorphosis and wing expansion of P. xylostella.

Key words: Plutella xylostella, bursicon, eclosion, gene expression, qRT-PCR, RNAi