紫胶虫在南岭黄檀上的取食部位及寄生对树皮结构的影响

FEEDING POSITION OF LACCIFER LACCA ON DALBERGIA BALANSAE AND THE INFLUENCE OF PARASITISM ON BARK STRUCTURE

紫胶虫[Laccifer lacca(Karr)Targ.]在南岭黄檀(Dalbergia balansae Prain)树皮中取食时,口针直接穿过生活细胞,口针尖最后抵达具功能筛管分子,在其中取食。口针尖距周皮表面0.48—0.78mm。被取食的筛管分子仍具 P-蛋白质,没有严重的伤害反应。口针穿过的薄壁细胞及周围的细胞有明显的反应。插在树皮中的口针外包被一层蛋白质组成的口针鞘。观察到空口针鞘有分叉的现象,有的分叉可及木质部,但最终口针抵达筛营分子。同时口针可穿过多个筛管分子而最后抵达新分化的筛管分子。采取不砍枝条而仅剥去胶块的方法收获后两年,树皮内口针与口针鞘仍残存,其周围数层细胞内充满黄褐色物并死亡。同时在周皮内形成许多囊状物。从结构上,此种树皮也不宜再固虫。

When Laccifer lacca fed in the bark of Dalbergia balansae,the penetration in the bark by a stylet was mainly intracellular,seldom intercellular.Finally,the styler arrived at Lhe funtional sieve element,and fed in it.The tip of the styler was at a distance of 0.48—0.78 mm from the surface of periderm.70.3% of the stylets fed in the zone of newly-differentiated sieve elements.The fed sieve element had P-protein and callose,and exhibited no serious reaction of injury.The parenchyma cells that were pierced through by the stylet and the neighbouring cells had obvious reaction of injury,such as:thiclened (?)ytoplasm arid plasmolysed;dark stained nuclei;smaller starch grains and intracellular deposition of concentrated golden ma- terial.The styler that pierced through the bark was encircled by a styler sheath consisted of proteins.The styler sheath looked like a string of beads as a whole.Branching stylet sheath was observed.Some branches even reached far into the xylem,but the stylet finally reached the sieve element.At the same time,the styler might penetrate through many sieve elements, finally reach newly-differentiated sieve elements.These results suggest that feeding of Laccifer lacca was a process of initiative choice.Two years after collecting shellac by means of skin- ning instead of cutting the branch,the stylets and styler sheaths still remained in the bark. Several layers of cells around them were dead and rally imbued with yellow-brown material. Stylets and stylet sheaths in the outer cortex were surrounded by bending phellogen and se- parated from the living cells,forming many cyst-like structures in the periderm.Such bark should not be further used for feeding.