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Issue:ISSN 2095-1353
           CN 11-6020/Q
Director:Chinese Academy of Sciences
Sponsored by:Chinese Society of Entomological;institute of zoology, chinese academy of sciences;
Address:Chaoyang District No. 1 Beichen West Road, No. 5 hospital,Beijing City,100101, China
Your Position :Home->Past Journals Catalog->2017年54 No.6

The relationship between degrees of Pinus yunnanensis canopy dieback and the types of damage caused by specific pests
Author of the article:LIU Yu-Jie1** ZONG Shi-Xiang1 REN Li-Li1 YU Lin-Feng1 GAO Bing-Tao1 ZE Sang-Zi2 LUO You-Qing1*
Author's Workplace:1. Beijing Key Laboratory for Forest Pest Control, Beijing Forest University, Beijing 100083, China; 2. Forestry Pest Control and Quarantine Bureau of Yunnan Province, Kunming 650032, China
Key Words: Pinus yunnanensis, wood boring pests, compound damage, linear stepwise regression model, dieback rate

[Objectives]  Pinus yunnanensis Franch is an important tree species in plantation forests in southwestern China. Recently, outbreaks of wood boring pests such as Monochamus alternatus Hope, Tomicus spp., Dioryctria rubella Hampson and brown-spot needle blight have been found in P. yunnanensis plantations, threatening local forest health. This study used the dieback rate of the tree canopy as an indicator of tree condition and identified the main factors that cause canopy dieback. A mathematical relationship between the degree of canopy damage and the species and abundance of pest insects was developed to improve the precision of pest monitoring methods and provide accurate early warning of pest infestation in P. yunnanensis plantations. [Methods]  In the sample areas, 35 P. yunnanensis with partly withered canopies and 29 completely withered trees were investigated. Species and amounts of different pests in the canopies and trunks of these trees were identified and counted. The correlation between dieback rate and damage factors was analyzed using Pearson correlation coefficients. A multiple linear stepwise regression was used to identify the main factors causing canopy dieback and model the major pest populations based on canopy dieback. [Results]  A highly positive relationship between dieback rate and Tomicus spp. abundance was found, whereas a weak, or no, relationship was found between dieback rate and diameter at breast height, shoot disease rate and other factors. A chi-square test showed that shoot disease didn’t influence shoot dieback significantly. We developed a regression model to estimate the population abundance of Tomicus spp. from dieback rate: Y=12.0984+0.9835 X, Adj-R²=0.8081. This indicated that tree vigor declined as Tomicus spp. abundance increased during the shoot feeding phase. Tomicus spp. and M. alternatus mainly damaged trunks of dying and withered trees during the trunk colonization phase. [Conclusion]  The shoot feeding behavior of Tomicus spp. causes partial withering of the canopy and a decline in the vigor of P. yunnanensis, whereas complete withering of the canopy and death follows colonization of the trunk by M. alternatus and Tomicus spp. The dieback model developed in this study can help estimate the mixed population of Tomicus spp. in canopies during the shoot feeding phase and provide a reliable theoretical foundation for pest space remote sensing or unmanned aerial vehicle monitoring.

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