Artificial light at night (ALAN) negatively affects expression of transcripts involved in biosynthesis of molting and...

Survival of organisms depends on their ability to adapt to their environment. Urbanization is increasing rapidly, resulting in elevated levels of artificial night illumination. A wide range of organisms may be affected by this global change in the urban environment. This study examined the effect of exposure to artificial light (0.0276 W/m²) at night (ALAN) on growth, development, and transcript expression of Bombyx mori, a common but economically important moth. The newly hatched B. mori larvae were randomly divided into two groups. Both groups were exposed to a daily light-dark cycle of 12L:12D (12 h light and 12 h dark), while group 1 served as the control. In group 2, the dark phase was illuminated with dim light at 0.0276 W/m². Cocoon quality parameters, including cocoon weight, cocoon shell weight, cocoon shell ratio, pupal weight, and fertilization ratio, were studied. Daily expression of clock genes (Per, Cry1, and Tim), transcripts involved in hormone synthesis (Nvd, Dib, Phm, Spo, Jhamt, and Ptth), and 20E-inducible transcripts (Hr3, Hr4, E75A, and Bftz) were measured. Results suggest that exposure to ALAN affects cocoon parameters, downregulates the daily rhythmic expression of Tim, and leads to a loss of rhythmicity in the expression of clock gene transcripts Cry1 and Per. Further, downregulation of hormone transcripts (Nvd, Dib, Phm, Spo, Hr3, E75A, Jhamt, and Ptth) was also observed in the treated group. These results are important, as they suggest that exposure to ALAN compromises silk moth development under laboratory conditions and may affect overall silk production/quality.