松材线虫在疫木内的分布动态

快速掌握松材线虫在其致病死松树体内的分布和种群动态对松材线虫病的早期诊断和除治具有重要的作用。于2016-2018年每个月在疫区不同小班中选择疑似松材线虫病松树作为样株,并对样株中不同部位进行取样,采用贝尔曼漏斗分离法统计松材线虫的种群密度,分析松材线虫在受害马尾松树体内的分布规律及种群消长动态。结果表明,每月均能在病死松树中检测出松材线虫,但检出率在不同月份间差异显著,其中以3月份检出率最高(84.09%),7月份最低(10.53%);松材线虫种群密度以6—9月份最低(59.37头/g),以11—4月份最高(118.03头/g);在垂直分布上,当整树虫口密度较高时,松材线虫在病树上的种群密度随树高高度的增高而增多,而虫量较少时则结果相反;在水平分布上,以向阳面深入木质部3～5 cm处最多,而树皮外缘1 cm左右和髓心部分的松材线虫含量极少。这些结果进一步说明松材线虫的种群密度和分布依不同月份和不同部位存在差异,且在3月份对疫木向阳面木质部3～5 cm处进行取样,能有效提高松材线虫的检出率和监测结果,为及时及早发现新疫点提供参考。

Population Dynamics and Distribution of Pine Wood Nematode, Bursaphelenchus xylophilus in Diseased Pine Trees

Rapidly understanding the distribution of the pine wood nematode Bursaphelenchus xylophilus(Nematoda:Aphelenchoididae) in diseased pine trees are helpful to earlier diagnose and treat this disease. In this paper, the population dynamics and distribution of B.xylophilus were investigated each month between 2016 to 2018, the different positions of suspected infected masson pine tree(Pinus massoniana Lamb) in different subcompartments in epidemic areas were randomly selected by use of Baermann funnel separation method. The results showed that:B.xylophilus were detected each month, but the average detection rate was significantly highest in March(84.09%) and lowest in July(10.53%). the population densities of B.xylophilus between June to September were significantly lower(<59.37 nematode/g) than that in November to April(>118.03 nematode/g).In vertical distribution, the amounts of B.xylophilus increased with the increase of tree height in higher population density, while the opposite result showed in lower population density in the diseased trees.In horizontal distribution, the amounts of B. xylophilus were mostly concentrated on the xylem 3-5 cm deep of the sunny side of the bark, while it was rare in the outer edge and the pith part of the bark. The results indicated that the population dynamics and distribution of B.xylophilus showed significantly difference among different months and positions of the diseased pine trees, and it would effectively improve the detection rate and the reliability of monitoring results when sampling was collected on the xylem 3-5 cm deep of the sunny side of the bark in March.