Studies On Cold-Hardiness Of Over-Wintering Pupae Of Hyphantria Cunea Drury

Hyphantria cunea Drury is one kind of International and domestic plant quarantine object. It is omnivorous large amount of propagation and have a good adaptability, they can damages plans for a long time and can spread throw many ways. In order to master its low temperature ecology, predict its quantity and dynamics of population growth, its over-wintering pupae cold-hardness mechanism was studied in the paper.1 Super cooling point and freezing point of the over-wintering pupaeFrom November to next March, the super cooling point(SCP) is -20.38℃,-26.42℃,-25.63℃,-27.07℃,-22.99℃.SCP and freezing point have the same trend with the variation of environment temperature. But SCP changed greater than the freezing point.2 The variation of water content of the body of over-wintering pupaeWater content of the pupae was measured by drying at 60℃unvaryingly. From November to next March, water content of the body is67.03%,65.07%,40.79%,30.76%,45.95% respectively. It shows that water content of the body have the same trend with the variation of environment temperature.3 Content of fat in the over-wintering pupaeDuring the over-wintering period, the content of dissociated fat in the pupae decreased from 29.52%to 17.25%, but the content of combined fat increased from 12.81% to 18.24%.After the period, the content of dissociated fat increases to 28.75% and the content of combined fat decreased to 9.64%.4 Content of glycerin and protein in the over-wintering pupaeContent of glycerin and protein in the over-wintering pupae has great effect on the improvement of the over-wintering pupae's cold hardiness. During the over-wintering period, content of glycerin in the over-wintering pupae rises from 3.74 mg/ml to 9.79 mg/ml, about 161.77 %.The content of protein in the over-wintering pupae's body decreases from 55.48% to 49.64%,but the content of protein in the over-wintering pupae's blood rises from 0.3958 mg/ml to 5.0848 mg/ml,increasing 118.47 %, protein in over-wintering pupae's body and blood maybe changes from each other, content of glycerin and protein in the over-wintering pupae's blood maybe have something on the cold hardiness of over-wintering pupae.5 Content of amino acid in the over-wintering pupaeContent of ALA, LYS , LEU and ILE in the over-wintering pupae's blood rises during the period of over-wintering and decreases at the end of over-wintering period. They raises158.46 %,382.33 %,7.00 %,6.12 % respectively and decreases 54.17 %,1.15 %,5.61 %,13.46 % respectively. Content of ALA, LYS and GLU in the over-wintering pupae's body has the same trend.6 Content of low-molecular carbohydrate in the over-wintering pupaeFrom non-over-wintering period to over-wintering period, content of every low-molecular carbohydrate in the over-wintering pupae's body rises. trehalose, fructose, sorbitol , mannitol and lactose raises 63.51 %,176.67 %,62.83 %,46.84 %,334.11 % respectively. But content of low-molecular carbohydrate in the over-wintering pupae's blood changes differently. trehalose,fructose, sorbitol , mannitol raises 140.10 %,252.14 %,125.23 %,275.69 % respectively. Trehalose, fructose, sorbitol , mannitol is important substances of cold hardiness.7 The system of cold hardiness substance in the over-wintering pupaeBased on the variation of chemical substance in the over-wintering pupae's body, we consider that the system of cold hardiness substance is made up of low-molecular carbohydrate (trehalose, fructose, sorbitol and mannitol)-amino acid(mainly by ALA and GLU)-glycerin-protein.