The Defense Responses Of The Poplar Strains Induced By The Damage Of Saperda Populnea

Saperda populnea is one of the important poplar trunk pest in the north of China. This insect mainly damage trunk especially the branches , by larvae. The damage form spindle cecidium.It impedes the normal transportation nutrients,so that the trunk dried and easily broken by wind. Recently, the rising population density and the pesticide area of Saperda populnea seriously damage the young poplars and threaten the afforestation achievement.In this paper, we determine the content of the nutrients and secondary metabolites of five major poplar strains in the western Jilin Province. By comparing the different index the phloem and xylem of all species turned out in different period, it provide scientific basis for the breeding of insect resistance trees and for the Saperda populnea L prevention. Poplar results of the indicators show that1.Make use of anthrone method to determine soluble total sugar, 3,5-dinitrosalicylic Acid(DNS) Method to Analyzing the Content of Reducing Sugar, Kjeldahl method to determine the nitrogen content. The total sugar contents of different poplar strains are extremely significantly different (P <0.01) except the xylem in March are significant different, reducing sugar contents in March are not different in the xylem, the others are significant different, the difference of nitrogen contents are not significant.2. Make use of vanillin-assay to determine the tannin, Folin-phenol method to determine total phenol content, UV-spectrophotometry to determine flavonoids content. The tannin contents in xylem of poplar different strains in September are significantly different, the flavonoid contents in June are not significant different, and the flavonoid contents in xylem in September are not different.3. The results show that the total sugar contents and total nitrogen contents in phloem of the poplar lines in larval damage period (June) are lower than the larvae damage period of the late winter (March), which is a direct pest of poplar defense response; the contents of total phenols and flavonoid in the xylem of poplar strains in the larval damage period (June) are higher than the end of larval winter (March), which is a pest of poplar defense response constitutively.Insect feeding induced plant defence is a complex system, and secondary metabolites plays an important role in it which can inhibit the strong growth and development of insects; the high content of nutrients in poplar may provide rich nutrients for the pest, and be easily infected by insects. In later studies, we can develop the total phenols or flavonoids as the main component of the chemical medicament to daub or spray on the skin of poplar, while it can forbid the female beetles to lay their eggs, on the other hand can suppress the larval worm's activities in the xylem and phloem of poplar, and ultimately achieving the purpose of pest nuisance-free control.