相思拟木蠹蛾调查及虫孔空间分布

为了研究柳州市主要园林绿化树种紫薇、荷花玉兰受相思拟木蠹蛾的危害情况及发生规律，为该虫防治提供一定的理论依据和参考。逐株调查紫薇、荷花玉兰行道树枝干上的虫孔数，计算其被害株率、有虫孔株率、平均每枝（株）虫孔数、不同高度的虫孔数及虫孔比例；采用分布型指数法及回归模型法探讨相思拟木蠹蛾的虫孔空间分布格局；并计算最适抽样及序贯抽样。结果表明，紫薇被害株率、有虫孔株率均100%，平均虫孔数5.8个/枝，枝条不同高度均有虫孔分布，以离地高度250~300 cm处虫孔最多，占总虫孔数的23.0%；荷花玉兰被害株率、有虫孔株率均为23.5%，平均虫孔数为3.1个/株，以离地高度200~250 cm处虫孔最多，占总虫孔数的20.4%。紫薇枝条上虫孔呈聚集型分布，分布的基本成分为个体群。当允许误差D=0.2，平均虫孔数5.8个/枝时，调查的枝条理论抽样数为14条；本次调查枝条数n=33枝，累计虫孔数为191个，远远超过防治指标上下限（113，86）。综上所述，紫薇、荷花玉兰受相思拟木蠹蛾的危害很严重，已极大地影响其观赏，造成枝枯现象，应及时进行防治。

Investigation and Spatial Distribution of Wormhole on Arbela bailbarana Mats.

In order to find out the hazard and the occurrence regularity of Lagerstroemia indica、Magnolia grandiflora by Arbela bailbarana Mats. in Liuzhou City, and provide the control of these pests with a theoretical basis and reference, by surveying the wormhole numbers of branches of L. indica and M. grandiflora to calculate the ratio of damaged trees, the ratio of trees with wormholes, the wormhole numbers per branch (strain) on average, the number and ratio of wormholes at different heights. Moreover, the spatial pattern of A. bailbarana was analyzed by the index of distribution and regression models and the optimal sampling and sequential sampling were calculated. The results showed that: the ratio of damaged trees, the ratio of trees with wormholes of L. indica were 100%, the average number of 5.8 wormholes per stick, and branches had wormhole distribution at different heights, the wormholes were at a maximum when the height above ground were 250~300 cm, accounting for 23.0% of total wormholes; the ratio of damaged trees, the ratio of trees with wormholes of M. grandiflora were 23.5%, the average number of 3.1 wormholes per plant, the wormholes were at a maximum when the height above ground were 200~250 cm, accounting for 20.4% of total wormholes. The wormholes of branches of L. indica showed aggregate distribution of which the basic components were individual groups. When the permissible error D was 0.2, the average number of 5.8 wormholes per branch, the theoretical sampling numbers of branches surveyed was 14; the numbers n of branches surveyed was 33, the total numbers of wormholes were 191 which were beyond the upper and lower limits of control index which was from 86 to 113. In summary，L. indica and M. grandiflora were harmed by A. bailbarana seriously which had greatly influenced their view and caused the phenomenon of withered branches. It should be timely cured.