Study On The Relation Of Damage Of Saperda Populnea And The Resistance Mechanism Of The Different Poplars In Heilongjiang Province

Saperda populnea belongs to the Coleoptera,Cerambycidae,Saperda,distributes in Heilongjiang,Qinghai,Beijing etc.It is one of the most destructive insect borers of poplar trees in China.In recent years millions of poplar trees were damaged to death or near death in "Three-North Area",which caused heavy losses in the economy,ecology and society. Analyzing the correlations between the fiture of the varieties of contents of secondary metabolites(tannin,phenolic compounds),nutriments(reducing sugar,free amino acid) in different damage stages and the larval growth of the Saperda populnea,and between the volatiles and the action of the Saperda populnea electing its parasitical plant and provided scientific basis for the selection of the resistant species and for the control.Studied on resistance of the different poplars to Saperda populnea,there was a very important significance on the comprehensive treatment of Saperda populnea.The research showed that:1 With the method of the vanillin colorimetry,we tested tannin.The result was that there was the strong minus correlation between the percentage of infestation and the contents of tannin of the healthy phloem and damaged xylem in the growing period of the different poplars;the difference was prominent among the different strains of poplars(P＜0.05);the percentage of tannin was obviously different in the healthy and damaged phloem and xylem in the growing period(P＜0.05);there was the strong correlation between the percentage of infestation and the percentage of tannin of the damaged xylem in the resting period;though there was not prominence in the percentage of tannin of the xylem in the growing and the resting period(P＞0.05),it was remarkable in the various percentage of tannin of the phloem(P＜0.05).We used the method of fehling regent colorimetry to examine phenolic acids.The absorbance of phenolic acid gross is proportional to the percentage of infestation.That is to say,the higher the absorbance of phenolic acid gross is,the lower the percentage of infestation is.The results showed that tannin and phenolic acid gross was one of the important factors of the resistance mechanism.2 With the method of 3,5-dinitrosaiicylic acid colorimetry,we tested reducing sugar.The result was that there was no correlation between the content of reducing sugar in the healthy xylem,damage xylem and healthy phloem and the percentage of infestation.But there was strong correlation between the contents of reducing sugar of damage phloem and the percentage of infestation.The result showed there was the strong plus correlations between the percentage of infestation and the contents of reducing sugar of the damaged phloem.Because reducing sugar was the important nutriment of ovum sucking in the period of ovum hatching larva in the phloem.By high performance liquid chromatography method with AccQ·Tag precolumn derivatization,the relationship between free amino acid of the different poplars and the damage of Saperda populnea to poplars was firstly analyzed.The results showed that fourteen free amino acids were detected in the phloem at the stem of tested poplar strain;the kinds of free amino acids in the xylem were similar to those in the phloem,except that THR was devoid of the xylem.In the phloem,there was the significant correlation between ARG or LYS relative contents and the ratio of damaged.In the xylem,there was significant correlation between ARG or HIS relative contents and the ratio of damaged.In the healthy or damage phloem and xylem,the distinction of the different free amino acids in different poplar strains were also remarkably different(P＜0.05).3 Distilled volatile and examined by GC-MS,there ware 48 kinds of volatile in all. Analysed various composition and content of volatile,it was not remarkable for the hydroxybenzene to attract or avoid insects on the first time.And there were some results: there were bigger percents of alkane,alcohol and aldehyde in the volatiles of the resistant Saperda populnea species;it was easy to attract insects by terpene and ketone;so far,only author educes that single species of terpene was easy to attract insects,but it was not easy to attract insects on this condition that there were more species of terpene and the percents of these species of terpene were in equilibrium.The resistance mechanism of tree is a complex system.Studied on secondary metabolite, it was a directly influence factor and inhibited the growth of the insects.But plant nutriment was a disadvantage factor on the aspect of resistance,and offered the favorable condition for the growth of insects.Different kinds of trees have different comether effects to Saperda populnea owing to the different volatile components and release rate in trees.