Study On The Induced Resistance Of Two Larch Species Treated With Exogenous Jasmonates To Insects

Larch pine is main species of forest in northeast of China.Dendrolimus superans(Butler) boomed since 90s in the twentieth century and serious harmful result was seen.In this research, Larix gmelinii and Larix olgensis were selected as objects for research.Temporal variation of chemical compounds in two larch species,and effects of host plant selection of Dendrolimus superans and of Anastatus japonicus,which were performed to analysis through treatment of jasmonic acid(JA),methyl jasnonate(MJA) and cis-jasmone.The influence of exogenous jasmonates induced resistance of two larch species to insects and relative biochemical mechanism to Dendrolimus superan and Anastatus japonicus were analyzed about the factors, such as nutrient compounds,defensive proteins and secondary metabolites.It was important for improveing the healthy level of forest and control of population density of Dendrolimus superan.By using analysis of chemical compounds and biometrics,results of the research were listed below:1.Changing of nutrient compounds in the needles of Larix gmelinii and L.olgensis induced with exogenous jasmonatesThe contents of soluble sugar in the needles of Larix gmelinii and L.olgensis was fluctuant variation,and which decreased at the 1^st,3^rd,10^th,15^th,20^th day,and which increased at the 5^th day after exogenous jasmonates application.The variation of the contents of soluble sugar was no significant difference.17 species of free amino acid were identified in the needles of Larix olgensis by HPLC.In contrasted with CK,the total contents of free amino acids increased at the 1^st,5^th,10^th day,and which decreased at the 3^rd,15^th,20^th day in the needles of L.olgensis after exogenous jasmonates application.The variation of the total contents of free amino acids was significantly different in the period of the experimentation.The component percents of free amino acids dropped at the 1^st,5^th,10^th day,and which raised at the 3^rd,15^th,20^th day in the needles of L. olgensis treated with jasmonates.But variational coefficient of free amino acids was smaller than one.Which sharp reversed with the variation of the total contents of free amino acids.The result indicated the variation of the component percents of free amino acids was normal fluctuation.2.Changing of secondary metabolites in the needles of Larix gmelinii and L.olgensis induced with exogenous jasmonatesThe contents of tannins changed significantly in the needles of Larix gmelinii and L. olgensis after exogenous jasmonates application.The contents of tannins in the needles of Larix gmelinii dropped at the 1^st,10^th day,and which raised at the 3^rd,5^th day.While which of L. olgensis decreased at the 1^st,10^th,20^th day,and which increased at the 3^rd,5^th,15^th day after application exogenous jasmonates.The contents of phenolic acid in the needles of Larix olgensis dropped at the 1^st,3^rd,5^th, 10^th day,and which raised at the 15^th day,then which dropped at the 20^th day after treated with exogenous jasmonates.The contents of phenolic acid in the needles of Larix gmelinii was decreasing in the period of the experimentation.11 species of phenolic acid were identified in the needles of Larix gmelinii by HPLC.There was similar variation for the contents of caffeic acid,ferulic acid,p-coumaric acid,phenylacetic acid,salicylic acid and vanillic acid.Which raised formerly,dropped later in needles of L.gmelinii induced with exogenous jasmonates. While which of cinnamic acid and chlorogenic acid sharp reversed with those.12 species of phenolic acid were identified in the needles of Larix olgensis by HPLC.The variation of the contents of caffeic acid,phenylacetic acid and salicylic acid dropped formerly,raised later in needles of L.olgensis treated with exogenous jasmonates.And which of cinnamic acid, chlorogenic acid,chlorogenic acid and vanillic acid sharp reversed with those.3.Changing of the activity of defendable enzymes in the needles of Larix gmelinii and L.olgensis induced by exogenous jasmonatesThe activities of PPO,PAL,trypsin inhibitor and chymotrypsin inhibitor increased significantly in the needles of Larix gmelinii and L.olgensis induced with exogenous jasmonates.The variation of their activity was waved in the period of the experimentation. While the induced function of the different concentration jasmonates was significantly different. Which indicated 2 species of larch pines formed the induced resistance to insect.4.Effect of two larch species induced with exogenous jasmonic acid on the behavior of host plant selection of Dendrolimus superansThe number of oviposition of Dendrolimus superans was significantly different in the seedlings treated with different concentration JA.The number of egg in control seedlings were much more than which in the seedlings treated with JA.There was not different for the number of eggs in the seedlings after different concentration JA application.There was strongly drivable for the seedlings treated with JA to the oviposition behavior of Dendrolimus superans.The drivable function of two larch species treated with JA to Dendrolimus superans was increased with prolonging days and increasing concentration treated with JA.Compared with CK,the drivable function of larch pine to Dendrolimus superans was not different at the 1^st day after jasmonic acid application,and which was significantly different at the 3^rd,5^th day following jasmonic acid application.5.Effect of two larch species induced with exogenous jasmonic acid on the behavior of host plant selection of Anastatus japonicusThe parasitism rate of Anastatus japonicus to Dendrolimus superans eggs was dropped with prolonging days treated with JA,and which was not different in the different treatments in the period of the experimentation.Which was waving with increasing concentration treated with JA.The attractive function of two larch species treated with JA to Anastatus japonicus was increased with prolonging days,and which was waving with increasing concentration treated with JA.Which was significantly different at the 1^st,5^th day following JA application.Therefore,this paper expounded exogenous jasmonates induced two larch species to form direct and indirect resitance to insects.Which prevented or disturbed pest insects feeding,and protected natural enemies.While induced resistance to insect maintained the balance of forest ecosystem,which would play a key role in pest integrated control.