松材线虫扩散型四龄幼虫向成虫转型发育阶段研究

通过光学显微镜观察松材线虫Bursaphelenchus xylophilus扩散型四龄幼虫(DL4)转型的形态结构变化过程以及油红染色后脂肪的特征变化,分析了不同植物对于转型过程的影响。结果表明:松材线虫由扩散型四龄幼虫向成虫转型分为5个阶段,定义为DL4,转型前期(TP),转型中期(TM),转型后期(TA)和转型末期(TT)。DL4阶段,头部钝圆,无溢缩,尾部较尖,无性别特征;TP阶段,线虫呈现竖直状态,可见头部蜕皮,出现口溢缩,尾部膨大;TM阶段,蜕皮明显,线虫开始弯曲,出现不显著的性别特征;TA阶段,进一步完成蜕皮,成虫状态表现明显,雌虫出现阴门盖,雄虫出现交合刺;TT阶段完成蜕皮。DL4时期脂肪含量最高,占据线虫全部身体;而转型前期则脂肪含量迅速下降,仅有头、尾和体表内侧较高;转型中期、后期和末期脂肪含量较少,脂肪颗粒化明显。松科植物红豆杉Taxus chinensis、圆柏Sabina chinensis、侧柏Platycladus orientalis、雪松Cedrus atlantica、油松Pinus tabuliformis、黑松Pinus thunbergii和马尾松Pinus massoniana促进转型效果明显,以黑松和马尾松木块刺激下松材线虫转型效率最高,而非松科植物银杏Ginkgo biloba无转型促进效果。

Developmental stages of Bursaphelenchus xylophilus from dispersal-stage larvae 4 to adult

The morphological,structural changes and fat content were observed by microscope during the transformation process of Bursaphelenchus xylophilus DL4,and the effect of different plant species to DL4 transformation was analysed.The results showed that the transformation process of B.xylophilus DL4 was divided into five stages including DL4,Transformation Prophase(TP),Transformation Metaphase(TM),Transformation Anaphase(TA) and Transformation Telophase(TT).At stage DL4,the nematode had a dome head and a pointed tail terminus,with no sex characteristics;at stage TP,the nematode presented a vertical stage,with molting cuticle at the head,spillage of the mouth and swelling of the tail;at stage TM,the nematode molted obviously and began to bend performing not clear sex characteristic;at stage TA,the molting process was going on with obvious adult status in which the female had vulva cover and male had spiculum;at stage TT,the transformation process was completed with molting successfully.The DL4 stage had the highest fat content and occupied the whole body of the nematode.While at stage TP,the fat decreased quickly except the head,tail and inner body surface.At TM,TA and TT,the fat contents were very low but grainy significantly.The transformation of process of B.xylophilus DL4 was promoted significantly by Pinidae plants such as Taxus chinensis,Sabina chinensis,Platycladus orientalis,Cedrus atlantica,Pinus tabuliformis,Pinus thunbergii and Pinus massoniana,especially by P.thunbergii and P.massoniana,while Ginkgo biloba had no effect on the transformation.