Insects enter in diapause in response to diverse environmental cues. During diapause, insects arrest their development and many genes are down-regulated while a small number of genes uniquely expressed at this time. T...Insects enter in diapause in response to diverse environmental cues. During diapause, insects arrest their development and many genes are down-regulated while a small number of genes uniquely expressed at this time. This review aims to present available data regarding the regulation of diapause in the moth Sesamia nonagrioides （Lepidoptera： Noctuidae）. Studying the transcriptional regulation of several genes （five heat shock proteins, two storage proteins and one juvenile hormone esterase） showed that these genes may play various roles in the diapause programming. The results show that SnoHsp19.5 gene was consistently expressed, while SnoHsp20.8 was down-regulated in deep diapause and was up-regulated at the termination of diapause. SnoHsc70 may play important roles in assisting protein conformation during specific stages of diapause. SnoHsp83 displays a similar pattern to SnoHsc70 under diapause conditions, when extra larval moults occur, indicating that could be involved in the developmental process that occurs between two moults. Expression of two SnoSP1 and SnoSP2 hexamerin genes was also observed throughout diapause. And the results lead us to the conclusion that larval diapause of S. nonagrioides is associated with continuous synthesis and accumulation of storage proteins. In addition, the transcript level of the carboxylesterase SnoJHER was higher in non-diapausing larvae than in diapausing ones. During the fifth instar of the non-diapausing and the ninth instar of the diapausing larvae, SnoJHER mRNAs reached higher expression levels on the days close to each larval molt.展开更多
Asian corn borer, Ostrinia furnacalis （Guenee）, is a key corn pest in the Asian-Western Pacific countries. It overwinters as flail-grown larvae in plant stalks or in a spun-silk covering located in the plant debris ...Asian corn borer, Ostrinia furnacalis （Guenee）, is a key corn pest in the Asian-Western Pacific countries. It overwinters as flail-grown larvae in plant stalks or in a spun-silk covering located in the plant debris in the temperate regions of China. Supercooling point （SCP） and survival rate after low sub-zero temperature treatment were assessed for field-collected populations in the laboratory using a cool bath with a 1 ℃/min cooling rate until -40℃. Mean SCPs were varied among geographical populations, with a significant decline from -22.7℃ of Haikou, the multivoltine tropical population in the south, to -28.5℃ of Gongzhuling, the univoltine temperate population in the northeast of China. In addition, there was more than 1℃ difference in SCP between Gongzhuling univoltine and bivoltine populations that were from the same geographic origin. Mean SCPs of the Guangzhou population fluctuated over the year, with significantly lower SCPs in winter than in other seasons, which correlated with a significantly higher proportion of diapausing larvae in winter than in other seasons. Over 41% of overwintering larvae from the northeast population could withstand to be supercooled for a few minutes to the low sub-zero temperature of-40℃, but only 6.7% of their southern counterparts did so. The findings from this study suggest that O. furnacalis mostly takes advantage of freeze avoidance as diapausing larvae for overwintering in the southern region, whereas it exhibits freeze tolerance in diapause in the northeastern region.展开更多
文摘Insects enter in diapause in response to diverse environmental cues. During diapause, insects arrest their development and many genes are down-regulated while a small number of genes uniquely expressed at this time. This review aims to present available data regarding the regulation of diapause in the moth Sesamia nonagrioides （Lepidoptera： Noctuidae）. Studying the transcriptional regulation of several genes （five heat shock proteins, two storage proteins and one juvenile hormone esterase） showed that these genes may play various roles in the diapause programming. The results show that SnoHsp19.5 gene was consistently expressed, while SnoHsp20.8 was down-regulated in deep diapause and was up-regulated at the termination of diapause. SnoHsc70 may play important roles in assisting protein conformation during specific stages of diapause. SnoHsp83 displays a similar pattern to SnoHsc70 under diapause conditions, when extra larval moults occur, indicating that could be involved in the developmental process that occurs between two moults. Expression of two SnoSP1 and SnoSP2 hexamerin genes was also observed throughout diapause. And the results lead us to the conclusion that larval diapause of S. nonagrioides is associated with continuous synthesis and accumulation of storage proteins. In addition, the transcript level of the carboxylesterase SnoJHER was higher in non-diapausing larvae than in diapausing ones. During the fifth instar of the non-diapausing and the ninth instar of the diapausing larvae, SnoJHER mRNAs reached higher expression levels on the days close to each larval molt.
文摘Asian corn borer, Ostrinia furnacalis （Guenee）, is a key corn pest in the Asian-Western Pacific countries. It overwinters as flail-grown larvae in plant stalks or in a spun-silk covering located in the plant debris in the temperate regions of China. Supercooling point （SCP） and survival rate after low sub-zero temperature treatment were assessed for field-collected populations in the laboratory using a cool bath with a 1 ℃/min cooling rate until -40℃. Mean SCPs were varied among geographical populations, with a significant decline from -22.7℃ of Haikou, the multivoltine tropical population in the south, to -28.5℃ of Gongzhuling, the univoltine temperate population in the northeast of China. In addition, there was more than 1℃ difference in SCP between Gongzhuling univoltine and bivoltine populations that were from the same geographic origin. Mean SCPs of the Guangzhou population fluctuated over the year, with significantly lower SCPs in winter than in other seasons, which correlated with a significantly higher proportion of diapausing larvae in winter than in other seasons. Over 41% of overwintering larvae from the northeast population could withstand to be supercooled for a few minutes to the low sub-zero temperature of-40℃, but only 6.7% of their southern counterparts did so. The findings from this study suggest that O. furnacalis mostly takes advantage of freeze avoidance as diapausing larvae for overwintering in the southern region, whereas it exhibits freeze tolerance in diapause in the northeastern region.
