Analysis of pine-wilt susceptibility-enchancing effect of co-occuring trees on pine trees

为研究三叶桤木的化感化学物质对松材萎蔫病易感性的影响，采用三叶桤木和日本木犀叶的风干叶和枝条加水提取液培养三叶桤木幼苗。使用的溶液稀释为1,10^<-1>,10^<-2>或10^<-3>。一周后在幼苗上接种木耳菌。在10^<-3>时，黄芪提取物对松材枯萎病的致死率高于黄芪提取物。为鉴定黄菖蒲叶的化感物质，对黄菖蒲叶的甲醇提取物进行了分离。在500和1000 ppm的浓度下，用i-BuOH提取的水馏分抑制了生菜的根生长，使根的末端呈棕色。^ c - nmr谱和生物测定表明，D-(+)-儿茶素是一种化感化学物质。对根生长的抑制作用是由儿茶素本身引起的，而不是由根的儿茶素代谢物引起的。为研究黄花散螨对松材枯萎病病媒繁殖的影响，将黄花散螨成虫分别饲养在室外网箱和盆栽中。不包括这两种树种的笼子作为对照。成年雌性的存活率和繁殖力没有差异。

To determine the effect of allelochemicals of Alnus sieboldiana on the susceptibility of Pinus trees to pine wilt disease.P.thunbergii seedings were cultured with the solution which was extracted from air-dried leaves and twigs of A.sieboldiana and Eurya japonica with water.The solution used was diluted at 1,10^<-1>,10^<-2> or 10^<-3>.Bursaphelenchus xylophilus was inoculated on seedlings a week later.Mortality from pine wilt was higher on A.sieboldiana extract than on E.japonica at 10^<-3>.To identify the allelochemicals of A.sieboldiana, methanol extract of the leaves was fractionated.Aqueous fraction extracted with i-BuOH inhibited the root growth of lettuce and made a terminal part of root brown at concentrations of 500 and 1,000 ppm.^3C-NMR spectrum and bioassay showed that D-(+)-catechin was an allelochemical.The inhibitory effect on root growth was induced by catechin itself and not by metabolites of catechin by root.To clarify the effect of A.sieboldiana on the reproduction of insert vector of pine wilt, Monochamus alternatus adults were raised in outdoor cages containing A.sieboldiana or Eurya japonica potted.Cages excluding both tree species were served as control.There were no difference among adult females in survivorship and fecundity.