Trehalose is a non-reducing disaccharide and participates in physiological activities such as organ formation, energy metabolism, and stress resistance in insects. The Bmtret1 gene family is mainly involved in in the sugar metabolism of silkworm. In the present study, phylogenetic analysis divided 21 Bmtret1 orthologs into three clades. These genes are equally distributed on the nine chromosomes. The cis-elements in the promoter regions of Bmtret1s indicated the possible function of Bmtret1s in response to hormones and environmental stimulus. The qPCR analysis showed the significantly different expression levels of Bmtret1s in different tissues and organs, indicating possible functional divergence. In addition, most Bmtret1s showed disturbed expression levels in response to silkworm nuclear polyhedrosis virus (BmNPV) stresses. Our results provide a clue for further functional dissection of the Tret1s in Bombyx mori and implicate them as potential regulators of antiviral responses.

Bombyx mori (Lepidoptera: Bombycidae) is an important economic insect, which mainly feeds on mulberry leaves and is widely used in many research fields. The growth and development of silkworm larvae are easily affected by the use of chemical insecticides such as novaluron, a benzoylurea insecticide. However, the effect of novaluron exposure on the reproduction of silkworms has not yet been studied. In this study, the effect of trace novaluron on the oviposition of silkworms and histopathological changes were first evaluated, and then the gene expression level changes after novaluron exposure were also determined by employing qRT-PCR. It was found that the number of eggs and the hatching rate of eggs in silkworms decreased significantly after feeding on leaves with a trace amount of novaluron (p ≤ 0.01). Furthermore, novaluron exposure could affect the development of ovary tissue by reducing the number of oocytes and oogonia in the ovaries of silkworms fed with novaluron. In addition, the transcription levels of genes related to ovary development (Vg, Ovo, Otu, Sxl-S and Sxl-L) and hormone regulation (EcR and JHBP2) showed varying degrees of downregulation at 24 h, 48 h, and 72 h after novaluron treatment (p ≤ 0.05). Therefore, we speculated that novaluron can affect the energy metabolism, ovary development, and egg formation of silkworms, thus leading to reproductive disorders of silkworms after novaluron exposure.

Bombyx mandarina is one of prevalent pests in mulberry gardens during summer and autumn, posing significant challenges to sericulture across China. Glutathione S-transferase (GST), a vital detoxification enzyme in insects, plays a crucial role in protecting organisms from DNA damage and oxidative stress. In this study, the GSTo3 gene, coding glutathione S-transferase of B. mandarina, was cloned and its physicochemical properties and structures were predicted using bioinformatics tools. The relative expression levels in various tissues and induced transcriptional levels were detected by using qRT-PCR. Results revealed a 99.17% sequence similarity of GSTo3 gene between B. mandarina and Bombyx mori. It is mainly distributed in the head, fat body and epidermis tissues of B. mandarina larvae. After BmNPV infection, elevated GSTo3 expression levels were observed in the midgut. The transcriptional levels of GSTo3 gene were significantly up-regulated after exposure to phoxim, deltamethrin and chlorfenapyr exposure respectively in the fat body and midgut of B. mandarina. These findings underscore the significance of GSTo3 gene in exogenous materials metabolism and provide a new perspective on the resistance mechanism in B. mandarina.