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The Research Of Pathogenicity And Ophiostomatoid Fungi Associated With Endemic Bark Beetles In Occurrence Area Of Dendroctonus Valens

Posted on:2011-05-13Degree:MasterType:Thesis
Country:ChinaCandidate:G L ChiFull Text:PDF
GTID:2143330332481656Subject:Forest Protection
Abstract/Summary:PDF Full Text Request
Bark beetles and fungus coexisting in forest ecosystem is a common ecology phenomenon in long-term co-evolution of biology.In the North China where Dendroctonus valens widespread, a variety of bark beetles exist and cause significant damage in some areas. The relationship between bark beetles and associated ophiostomatoid fungi are complex and diverse,and there are a wide range of related fungi, changing with different host trees. Meanwhile, it lack systematic research about the relationship between bark beetles and the associated ophiostomatoid fungi currently, so the damage mechanisms of bark beetles and their associated ophiostomatoid fungus on the host plants are still need further study.The object in this experiment are bark beetles and their associated ophiostomatoid fungi, conducting on isolation and identification of ophiostomatoid fungi, and their biological characteristics and pathogenicities.(1) Surveies of Bark beetles damages. It can be seen from the investigation result of the five standard plots, the most serious damages was discovered in the AnJiaZhuang Forest Farm, and the highest damage rate has reached 10-35%. Also the most abundant species were collected in this Farm—5 species of bark beetles, which may be connected with serious harms caused by bark beetles, seriously harvesting of trees and the weak forest tree vigor;bark beetle damages in LinKongShan and TieQiao Forest Farm was moderate, and the rates were 7-21% and 8-20%; the lowest bark beetles damages rate occured in YeYuGou and HeShun Country Forest Farm, were 6-11% and 3-10.5%, at the same time, the two places of the ophiostomatoid fungus separation frequency are lower.(2) Isolation and identification of ophiostomatoid fungus associated with bark beetles, and Pathogenicity testing.344 phloems (sapwoods) and worm fragments from 86 samples collected were isolated into 103 strains, and the isolation rate was about 30%. There are more than five species of fungi testing by the preliminary identification. Observing their morphologies and testing ITS sequences, blast searches with Genbank obtained in part by the strain of building a phylogenetic tree. Based on morphological characteristics and molecular phylogenetic tree, it determines four kinds of ophiostomatoid fungus. They are Leptographium. sinoprocerum, Leptographium. truncatum, Leptographium. koreanum and Ophiostoma ips. The strains isolated are tested by two methods of trunk inoculation and root inoculation, and the results show that the Leptographium. truncatum and Leptographium. koreanum have strong pathogenicity.(3) The possible role of ophiostomatoid fungus in the death of Pinus. tabulaeformis, and the control countermeasure to bark beetles. As these associated fungus display strong pathogenicity, combined with habits of bark beetles attacking host, it may make for the analysis of the pathogenicity of associated fungus. The ophiostomatoid fungus associated with bark beetles played an important role in reducing the pine's resistance and growth. The ophiostomatoid fungi collaborated with bark beetles, effected by global warm, abnormal weather conditions and other factors, lead to host pine tree decline and even death.In order to eliminate severe harm of the bark beetles, strengthen its monitoring, we can consolidate preventive measures of biology, chemistry, physics and other control method, timely control and prevent the spread of bark beetle damage; protect and improve the forest environment, protect and utilize the natural enemies of bark beetles and make use of biological measures to manage bark beetle damages sustainability and coordinate the development of economy and ecology.
Keywords/Search Tags:Dendroctonus valens, bark beetles, ophiostomatoid fungi, pathogenicity
PDF Full Text Request
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