Impact of chromafenozide on the expression of Halloween gene and nuclear receptor gene in Tetranychus cinnabarinus (Boisduval)

Tetranychus cinnabarinus (Boisduval), a worldwide acarine pest, has garnered significant attention in recent studies, particularly regarding the role of ecdysteroids. Ecdysteroids (moulting hormone) played key roles in regulating the important physiological processes of arthropods, such as ecdysis, metamorphosis reproduction and immunity. However, the underlying mechanisms of ecdysteroid biosynthesis and signalling have not been elucidated in T. cinnabarinus. Therefore, in this study, we utilized RACE technology in conjunction with RT-PCR to obtain the complete sequence of three Halloween genes disembodied (dib), shadow (sad), shade (shd) and ecdysone receptor (EcR). Moreover, we analysed the expression level of these target genes in T. cinnabarinus, which was found to be expressed at all developmental stages. When using sublethal concentration of chromafenozide for bioassay on nymph of T. cinnabarinus, as the concentration increased, the ecdysis rate, mortality and ecdysteroid content were increased, and the moulting duration was decreased. We also characterized the expression on nymph of T. cinnabarinus after treatment with sublethal concentrations of chromafenozide, which were up-regulated. Based on these findings, we concluded that the treatment of sublethal chromafenozide enhanced Halloween gene and nuclear receptor gene expression, aided in the investigation of the molecular regulatory mechanism for moulting of T. cinnabarinus, and provided a theoretical basis for new agents.