祥云新松叶蜂发生和危害分布与寄主植物特征的关系

HOST PLANT CHARACTERISTICS ASSOCIATED WITH THE DISTRIBUTION PATTERN OF THE PINE SAWFLY, NEODIPRION XIANGYUNICUS

本文对不同海拔和密度的云南松林分内祥云新松叶蜂（Ｎｅｏｄｉｐｒｉｏｎｘｉａｎｇｙｕｎｉｃｕｓ）的发生和危害进行了调查，调查表明该虫的发生和危害与海拔高度有密切关系，与林分密度没有显著关系。其危害局限于海拔１９００ｍ以上林分；１８５０～１９００ｍ林分有成群分布，但无危害；１８５０ｍ以下林分则无成群分布。依不同海拔高度将松叶蜂的发生和危害分为三个类型，分别对不同类型林分松针的韧度、长度、宽度松针干物质、全氮含量、松针油中萜烯类物质种类和含量、松针组织解剖结构进行了比较研究，结果表明，不同类型云南松林分松针韧度、松针表皮细胞厚度、松脂道直径、松针油中萜烯含量组成以及松针全氮和干物质含量与该虫的发生和危害有着密切关系。祥云新松叶蜂发生和危害选择松针韧度低、表皮细胞薄、低氮和低水份含量的高海拔林分。

Distribution patterns of the pine sawfly (Neodiprion xiangyunicus) were investigated in relation to site elevation and forest stand density. The pine sawfly was found to be restricted to pure stand of its host at specific elevations based on transect studies. Defoliation and oviposition on Yunnan pine(Pinus yunnanensis) by N.xiangyunicus was confined to a specific elevational band (1900～2100m) within the host range of the area(1650～2100m). Stand density did not appear to have a significant influence on N.xiangyunicus distribution pattern. The defoliation and oviposition by N.xiangyunicus were divided into different levels based on the site elevation. The toughness, length and width of pine needle in 1700m and 1950m sites, the needle dry weight, total nitrogen, tissues of needle, terpenes of needle oils in 1700m,1950m and 2050m sites were researched. It was found that the toughness of needle in 1700m and 1900m sites, the thickness of epidermis, the diameter of resin ducts, the total nitrogen and the dry weight of needle in 1700m, 1950m and 2050m sites had a close relation to the defoliation and oviposition by N.xiangyunicus. The pine sawfly was distributed in the site with higher elavation lower needle toughness, smaller thickness of epidermis, lower nitrogen content and lower dry weight of needle.