Abstract: To understand the molecular characteristics of diapausing larvae of the rice stem borer, Chilo supprressalis, we analyzed the contents of proteins and nucleic acids in non-diapausing mature larvae reared under a long photoperiod of 16L∶8D at 25℃ and diapausing larvae with the diapause duration of 0-3 months induced under a short photoperiod of 12L∶12D at 25℃ by using Trizol method, total DNA extraction and protein quantitative kit, and the activities of protective enzymes (POD, CAT, SOD, LDH and ATPase) in non-diapausing mature larvae and diapausing larvae with the diapause duration of 0-2 months. The results showed that the RNA content in diapausing larvae was significantly lower than that in non-diapausing mature larvae (P<0.05), but was not significantly different among diapausing larvae with different diapause duration (P≥0.05). The DNA content in non-diapausing mature larvae was significantly higher than that in diapausing larvae. The RNA/DNA ratio increased first and then decreased with diapause progress. The RNA/DNA ratio in non-diapausing mature larvae was higher than that in diapausing larvae. The protein content in diapausing larvae was significantly higher than that in non-diapausing mature larvae, but it was not different among the diapausing larvae with different diapause duration of 1-3 months. Activities of CAT, POD, and SOD were the lowest in non-diapausing mature larvae and the highest in diapause larvae with the diapause duration of 2 months, while activities of LDH and ATPase were the highest in non-diapausing mature larvae and the lowest in diapausing larvae with the diapause duration of 2 months. These results suggest that diapausing larvae of the rice stem borer are characterized by low RNA and DNA contents and high protein content, and variations in activities of protective enzymes.

Key words: Chilo supprressalis, diapause, nucleic acid content, protein content, RNA/DNA ratio; , protective enzymes