南非刺桐叶片上刺桐姬小蜂虫瘿分布特征

Distribution of Galls Induced by Quadrastichus erythrinae on the Leaf of Erythrina caffra

对刺桐姬小蜂(Quadrastichus erythrinae Kim)虫瘿在南非刺桐(Erythrina caffra Thunb.)叶片上的分布特征进行了调查研究。结果表明:刺桐姬小蜂主要危害南非刺桐的叶片和叶柄,树冠不同方位上其叶片受害率和受害叶虫瘿平均密度差异不显著(P>0.05);在树冠的不同层次上其叶片受害率差异极显著(P<0.01),主要表现为上层>中层>下层;但各层次的受害叶虫瘿平均密度差异不显著(P>0.05)。虫瘿主要分布于叶片的基部和叶柄的中、上段部位,以单个和2个虫瘿相连的虫瘿团出现。南非刺桐叶片上刺桐姬小蜂虫瘿呈聚集分布,且聚集程度较强,其分布形式符合负二项分布,分布的基本成分为个体群,虫瘿聚集程度具有密度依赖性,聚集是由昆虫本身的习性和环境共同引起的。

Quadrastichus erythrinae Kim is an important invasive pest which affected Erythrina caffra plants. The distribution of galls and infested characteristics induced by Q. erythrinae Kim on Erythrina caffra Thunb. leaves were investigated and analyzed to guide the control of these invasive pests. The results indicated that Q. erythrinae was one of the main pests which infested primarily leaves and leafstalks, and there was remarkable difference in damage ratio among different parts of the crown with the highest damage ratio in the upper crown, the lowest ratio in the lower crown, while no remarkable difference in damage ratio of leaves and average gall density in different orientations of the crown. Galls were mainly distributed in the leaf base and petiole top, and the probability of the gall mainly appeared with one and twogalls group. The spatial distribution of the galls on leaves was aggregate based on the spatial pattern parameters, and its basic element for distribution was clusters of individuals, and the aggregation degree was dependent on the gall density, which was caused by the congregation habits of insects and the environment condition.