Nuclear receptor genes HR3 and βFTZ‐F1 are involved in moulting development, pupation and eclosion in Hyphantria cunea (Drury)

Nuclear receptor genes play crucial roles in insect moulting. These genes, found in all insects, produce important proteins that control the expression of other genes, which in turn regulate the moulting process in larvae. This study investigated the roles of the nuclear receptor genes HcHR3 and HcβFTZ-F1 in the moulting development, pupation and eclosion of Hyphantria cunea. The mRNA expression of the two genes was detected at all developmental stages and in various adult tissues. A novel pET28a (+)-HT115 (DE3) RNase III-system was successfully constructed to efficiently express HcHR3-dsRNA and HcβFTZ-F1-dsRNA in bacteria. To explore the physiological functions of these genes, they were knocked down in larvae and pupae using the dsRNA extracted from bacteria, resulting in a decrease in the expression levels of HcHR3 and HcβFTZ-F1 by 13.70% and 99.01%, respectively. Moulting defects were observed in H. cunea larvae following HcHR3 and HcβFTZ-F1 silencing, with a phenotypic percentage ranging from 33.40% to 45.22%. Additionally, knockdown of these two genes in 5th instar larvae decreased weight, food intake and the survival rate, resulting in abnormal development during the larval-pupal transition. RNAi-mediated knockdown of HcHR3 and HcβFTZ-F1 prevented the eclosion of the pupae, with malformation rates ranging from 75.67% to 80.12%, and epidermal tanning defects were observed in pupae and adults. Our findings demonstrate that HcHR3 and HcβFTZ-F1 are indispensable for normal postembryonic development and provide validated molecular targets for RNAi-based pest management and insight into the outbreak mechanisms of H. cunea.