Abstract:  【Aim】 Bursicon secreted by nervous system is a heterodimer neuropeptide and plays an important role in regulating cuticle hardening and wing expansion of insects during molting cycle. This study aims to investigate the relationship between Bursicon genes and the genes involved in wing development and fecundity in Bombyx mori and to ascertain their role in regulating wing expansion and fecundity. 【Methods】 The RNAi technique was used to silence the Bursicon genes by injecting Bursicon dsRNA (dsBmBurs-α, dsBmBurs-β and dsBmBurs-α+dsBmBurs-β) into the 1-day-old pupae of B. mori, and the individuals injected with dsGFP were used as the control. After RNAi, the phenotype of B. mori was observed, and the number of eggs laid per female was calculated. The real-time quantitative PCR technology was used to detect the expression levels of wing development-related genes (BmWg, BmFt, BmFj and BmDs)  in the 24 h-old adults of B. mori and reproduction-related genes (vitellogenin gene BmVg and vitellogenin receptor gene BmVgR) in pupae at 48 and 72 h after RNAi. 【Results】 After RNAi of Bursicon genes, the wings of the 24 hold adults of B. mori were not able to expand normally. In the three treatment groups injected with dsBmBurs-α, dsBmBurs-β and dsBmBurs-α+dsBmBurs-β, the wing deformity rates were 93.33%, 96.67% and 96.43%, respectively, and the average numbers of eggs laid per female were 312.67, 332.00 and 284.00, respectively, significantly lower than that of the control (406.00). After RNAi of Bursicon genes, the expression levels of Bursicon genes BmBurs-α and BmBurs-β in B. mori decreased significantly, and the expression levels of the related genes BmWg, BmFt, BmFj, BmDs, BmVg and BmVgR were significantly lower than those of the control group. 【Conclusion】 Bursicon genes are involved in regulating wing expansion by regulating the transcription levels of genes related to wing development in B. mori. They also regulate the expression of reproduction-related genes BmVg and BmVgR, and thus influence reproduction in B. mori.

Key words: Bombyx mori, Bursicon, wing expansion, fecundity, Hippo signaling pathway