Abstract: 【Aim】 This study aims to clarify the molecular characteristics and expression patterns of juvenile hormone receptor genes (Met) and to analyze their functions in reproductive regulation in the diamondback moth, Plutella xylostella, so as to provide basis for screening new targets for effectively controlling the diamondback moth. 【Methods】 Based on the genome database of P. xylostella we obtained previously, the fulllength cDNAs of two Met genes were cloned using PCR, and their expression patterns in different developmental stages and adult tissues of P. xylostella were detected via qPCR. Moreover, the role of the two Met genes in the reproductive development of female adults of P. xylostella was analyzed by RNAi. 【Results】 The cDNA sequences of PxMet-1 (GenBank accession no. MK697672) and PxMet-2 (GenBank accession no. MK697673) were cloned from P. xylostella, and they contain ORFs of 1 575 bp encoding 524 aa and 2 100 bp encoding 699 aa, respectively. The predicted molecular mass of PxMet-1 and PxMet-2 are 60.5 and 70.7 kD, and the theoretical isoelectric points are 6.73 and 5.50, respectively. PxMet-1 and PxMet-2 both contain a basic helix-loop-helix (bHLH) domain, two PAS motifs and one PAC motif. The results of phylogenetic tree analysis showed that PxMet-1 and PxMet-2 were clustered into different branches, but clustered into the same branch with lepidopteran Mets. The expression profiles showed that PxMet-1 and PxMet-2 were both expressed in the pupal stage (1-3 d after pupation) and female adult (0-72 h after eclosion). The expression level of PxMet-1 in the pupal stage (1-3 d after pupation) showed no significant difference, but was significantly higher than that in female adult (0-48 h after eclosion), and its expression peaked at 72 h after eclosion. In the female adult (0-48 h after eclosion), the mRNA level of PxMet-2 firstly increased, reached a peak at 12 h after eclosion, and then decreased. Moreover, the expression level of PxMet-2 at 0-36 h after eclosion was significantly higher than that in the pupal stage. The expression levels of PxMet-1 and PxMet-2 in the fat body of adult were significantly higher than those in other tissues. Injection of dsPxMet-1 and dsPxMet-2 significantly inhibited the expression of PxMet-1 and PxMet-2 within 24 h. In the female adults of P. xylostella with both PxMet-1 and PxMet-2 silenced, oogenesis was significantly inhibited, and the number of eggs laid per female within 3 d after eclosion significantly reduced. 【Conclusion】 Inhibition of the expression of PxMet-1 and PxMet-2 can significantly reduce egg maturation and oviposition of female P. xylostella. This study establishes a theoretical foundation for reproductive regulation mechanisms by JH in P. xylostella and facilitates screening potential targets used for genetic manipulation of P. xylostella populations.

Key words: Plutella xylostella, juvenile hormone receptor, Met; molecular characteristic, expression profile, reproductive regulation, pest management