| Diaphania pyloalis Walker is one of the main pests in the mulberry field. It distributes widely, especially in Tai'an and Linyi, Shandong province. In order to predict its quantity and development rule and prevent it from erupting, its cold-hardiness and effective accumulation temperature was studied in the paper.1 Death rate of the over-wintering larvae The death rate of over-wintering larvae is the highest in the dead woods and scatters, which is 87.62%; the lowest indoors which is 55%; the middle in crevice which is about 75%.The death rate ties up with the environment temperature. The chilliness flow at the end of the over-wintering period affects the death rate greatly. 2 Super cooling point and freezing point of the over-wintering larvae From September to next April, the super cooling point(SCP) is -7.16℃,-9.36℃,-11.32℃,-18.38℃,-18.88℃,-19.69℃,-15.46℃,-8.24℃ respectively and the freezing point is -5.62℃,-7.46℃,-8.52℃,-9.77℃,-10.74℃,-11.78℃,-9.35℃,-5.44℃ respectively. SCP and freezing point have the same trend with the variation of environment temperature. But SCP changes greater than the freezing point. 3 The variation of water content of the body of over-wintering larvae Water content of the larvae's body was measured by drying at 60℃ unvaryingly. From September to next April, water content of the body is 72.59%,70.03%,68.36%,67.92%,67.57%,66.90%,68.76%,69.79% respectively. It shows that water content of the body have the same trend with the variation of environment temperature. But fall behind the latter. 4 Content of low-molecular carbohydrate in the over-wintering larvae From non-over-wintering period to over-wintering period, content of every low-molecular carbohydrate in the over-wintering larva's body rises. trehalose, lactose, fructose, mannitol, glucose and sorbitol raises 53%,66%,52%,28%,21% respectively. The whole contents of low-molecular carbohydrate in the over-wintering larva's body rise from 54.22mg/g to 78.64mg/g, about 45%. But content of low-molecular carbohydrate in the over-wintering larva's blood changes differently. trehalose, fructose, mannitol and sorbitol raises 62%,714.3%,315%,346% respectively, on the other hand, lactose and glucose reduces 98% and 34%.The whole content of low-molecular carbohydrate in the over-wintering larva's blood rises from 36.02mg/g to 45.89mg/g. Trehalose, fructose, mannitol and sorbitol is important substances of cold hardiness.5 Content of amino acid in the over-wintering larvaeContent of SER, ALA, TYR, LYS and ARG in the larva's blood rises during the period of over-wintering and decreases at the end of over-wintering period. They raises 84.75%, 783.06%, 110.41%, 26.07%, 23.56% respectively and decreases 85.21%, 76.42%, 51.79%, 21.56%, 28.4% respectively. Content of SER and ALA in the larva's body has the same trend.6 Content of glycerin and protein in the larvae Content of glycerin and protein in the larvae has great effect on the improvement of the larva's cold hardiness. During the over-wintering period, content of glycerin in the larvae rises from 3.85 mg/ml to 10.82 mg/ml, about 181%. The content of protein in the larva's body decreases from 33.61% to 23.49%, but the content of protein in the larva's blood rises from 3.184 mg/ml to 6.089 mg/ml, increasing 91.23%, protein in larva's body and blood maybe changes from each other, content of glycerin and protein in the larva's blood maybe have something on the cold hardiness of larvae.7 Content of fat in the over-wintering larvae During the over-wintering period, the content of dissociative fat in the larvae decreases from 22.51% to 20.73%, but the content of combined fat increases from 5.16% to 8.24%.After the period, the content of dissociative fat increases to 22.39% and the content of combined fat decreases to 5.81%.8 The system of cold hardiness substance in the over-wintering larvae Based on the variation of chemical substance in the over-wintering larva's body, we consider that th... |
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