Abstract: To understand the molecular regulation of diapause in the beet webworm, Loxostege sticticalis L., we analyzed the contents and compositions of proteins and nucleic acids in non-diapause larvae, diapausing larvae with the diapause duration of 1, 2, 3, and 4 months, and post-diapause larvae of this species by using Trizol method, DNA and protein quantitative kit, and SDS-PAGE technique. The results showed that the RNA content in the diapausing larvae with the diapause duration of 1 to 4 months was significantly lower than that of the non-diapause larvae. Although RNA content in the post-diapause larvae increased significantly as compared with that of the diapausing larvae with the diapause duration of 2, 3 and 4 months, it was significantly lower than that of the non-diapause larvae. The DNA content among these treatments was not significantly different, but the RNA/DNA ratio in the diapausing larvae with the diapause duration of 1 to 4 months was lower than that in the non-diapause and post-diapause larvae. The protein content in all the diapause larvae was significantly higher than that in the non-diapause larvae, but there was no significant difference between the non-diapause and the post-diapause larvae. A protein band of 24 kDa was found in the diapausing larvae with the diapause duration of 1 to 4 months but was not detected in the non-diapause and post-diapause larvae by using the SDS-PAGE technique. These results suggest that the lower RNA content, the lower RNA/DNA ratio, and higher protein content, as well as the presence of 24 kDa-protein, are the major characteristics of the diapause larvae distinguishing from the non-diapause and post-diapause larvae of L. sticticalis.

Key words: Loxostege sticticalis, diapause, nucleic acid content, protein content, RNA/DNA ratio