Occurrence and spatial distribution of white peach scale, Pseudaul acaspis pentagona (Tagioni-Tozzetti) (Homoptera: Diaspididae) on apricot trees | 桑白蚧在杏树上的发生规律与空间分布研究

Chinese. 揭示桑白蚧在杏树上的发生规律与空间分布格局，为控制桑白蚧的危害提供依据。在陕西礼泉选择代表性杏园，周年系统调查桑白蚧种群的消长动态；选择1~5，6~10，11~15，16~20和20年 5个树龄段的杏园，调查不同树龄、高度（上、中、下）、方向（东、南、西、北）对桑白蚧危害的影响；选择3个代表性杏园，调查每株树上桑白蚧的数量，采用聚集指标法测定其空间分布型。桑白蚧以雌成虫在树干被害部位越冬，成虫发生高峰期分别为4月中旬和6月下旬至7月中旬，若虫发生高峰期分别为5月中旬和7月下旬。树龄对桑白蚧的发生影响显著，以11～15年及16～20年2个树龄段的杏树受害较重，其次是1～5年和6～10年树龄段的杏树，20年以上树龄的杏树很少受害。在同一杏树的不同高度和不同方向，桑白蚧危害程度无显著差异。桑白蚧种群在杏树上分布的各项聚集度指标值分别为扩散系数_C=0.414 1，扩散指数Iσ=0.713 8, 聚集指数CA=-0.292 0，平均拥挤度M*=0.702 3。桑白蚧在陕西礼泉1年发生2代，其危害对杏树的方位没有选择性，而对树龄具有选择性；成虫在杏树上属均匀分布型。

English. The study was to understand the occurrence characteristics and spatial distribution, which is basic work for effective prevention and control of Pseudaulacaspis pentagona (Tagioni-Tozzetti) on apricot trees. Population dynamics in a year cycle and distribution characteristics of P. pentagona on the branches with different ages of 1-5, 6-10, 11-15, 16-20 and over 20 years, different heights and different directions (East, South, West and North) were investigated in some selected apricot orchards. Spatial distribution pattern of P. pentagona was investigated and analyzed with the method of aggregation index in 3 representative apricot orchards. Female P. pentagona adults overwinters in the damaged tree trunks and branches. Adults appear abundantly in mid-April and late June to mid-July respectively. Nymph peak occurs in mid-May and late-July respectively. The occurrence of the pest is affected by tree ages significantly. Trees with the age of 11 to 15 and 16 to 20 years are damaged severely, but those over 20 years old are rarely affected by this pest. No significant difference of damage is found between branches with different heights or directions on the apricot trees. The aggregation indexes of population distribution of this pest on apricot trees are C=0.414 1, Iσ=0.713 8, CA=-0.292 0, M*=0.702 3, respectively. P. pentagona has two generations in a year life cycle in the local area. The spatial distribution of adults on the apricot trees is uniformly distributed.