Abstract:

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.