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

为了研究侧柏化感物质对松树对松材线虫病的感病作用，用从侧柏和水杉枝叶风干后提取的水溶液对松材线虫苗木进行了培养。将水溶液分别稀释到1、10、2和10℃时，接种松材线虫1周后苗木上松材线虫的死亡率高于松材线虫。为了鉴定天南星的化感物质，从叶的甲醇提取物中分离得到。用异丁醇提取的水提物在500ppm和1000ppm的浓度下抑制生菜的根生长，并使根的末端变成棕色。~(13)C-核磁共振谱和生物活性测定表明，D-儿茶素是一种化感物质。抑制根生长的作用是由儿茶素本身诱导的，而不是由根中的儿茶素代谢产物诱导的。为了阐明天南星对松材线虫插入载体繁殖的影响，松墨天牛成虫饲养在装有松墨天牛或日本松墨天牛盆栽的室外网箱中，不含这两种树种的网箱作为对照。成虫的存活率和繁殖力在成虫之间没有差异。

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.