两种盾蚧对库尔勒香梨果实的危害特性研究

Damage caused by two kinds of scale insect on Pyrus sinkangensis

【目的】为了澄清香梨Pyrus sinkangensis果实上红色斑点的形成原因和危害果实的蚧虫种类及扩散传播途径。【方法】以定点人工接虫法观察两种盾蚧对香梨果实各发育阶段造成的危害特性,悬挂黄板阻截法监测了杨盾蚧若虫的扩散距离。【结果】在香梨果实幼果期危害果实的是杨盾蚧Quadraspidiotusslavonicus (Green)1龄若虫,5月下旬至6月上旬以1龄若虫随风从香梨园周边杨树林带飘落到香梨叶片、果实上并在香梨果实表面危害形成红色斑点。在自然风力2-3级时,杨盾蚧1龄若虫最远可扩散到50m处,黄板上截获的平均虫口密度为0.01头/cm2;风力5-6级时,可扩散到150 m处,黄板上截获的平均虫口密度为0.24头/㎝2。在香梨果实膨大期,即7月中旬梨圆蚧第2代1龄若虫在梨树靠自身爬行能力扩散到果实上,并在香梨果实表面危害形成斑点(危害果实着色部位时可形成深红色斑点;危害果实未着色部位形成深绿色的斑点),使果实畸形。【结论】在香梨果实幼果期果实上引起红色斑点的蚧虫是杨盾蚧1龄若虫;杨树林带的高度、风力的大小以及虫源木上的虫口数量是影响杨盾蚧扩散数量和距离的重要因素。在香梨果实膨大期(即7月中旬)在香梨果实表面危害形成斑点,使果实畸形蚧虫是梨圆蚧Quadraspidiotus perniciosus (Comstock)的第2代若虫。

[Objectives] To clarify the cause of the red spot on Pyrus sinkangensis, identify the scale insects that damage the fruit of this species and how these spread.[Methods] The damage caused by two kinds of scale insect were observed during the development of pear fruit by artificially inoculating P. sinkangensis at fixed points. The subsequent spread of these pests was monitored using the hanging yellow board method.[Results] During the the fruit growing period, second generation nymphs of Quadraspidiotus perniciosus crawl onto the fruit and cause the spots visible on the surface of fruit in the middle of July. Dark red spots occur where the fruit is reddish and dark green spots when damage occurs in unpigmented areas. Early stage fruit are harmed by 1 st instar nymphs of Quadraspidiotus slavonicus(Green). 1 st instar nymphs of this species drift on the wind to pear leaves and fruits from adjacent poplar forests causing red spots to appear on the surface of fruit in late May and early June. When the wind scale was about 2-3, 1 st instar nymphs of Q. slavonicus dispersed a maximum of 50 m and the mean number caught on yellow sticky boards under these conditions was 0.011 per one cm2. When the wind scale was about 5-6, 1 st instar nymph could disperse up to 150 m, and the mean number caught on yellow sticky boards was 0.239 per one cm2.[Conclusion] The red spots on young fruit of P. sinkangensis are caused by 1 st instar nymphs of Q. slavonicus. Important factors influencing the spread of this pest to P. sinkangensis orchards are the height of the poplar forest zone, the wind force,and the number of insects. Spots on pears during the P. sinkangensis fruit growing period(mid-July) were caused by 2 nd generation nymphs of Q. perniciosus.