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Susceptibility Variation Against Ectropis Obliqua Nucleopolyhedrovirus and Genetic Variation in Geographic Populations of Tea Geometrid, Ectropis Obliqua Prout

Author: XiYu
Tutor: XiaoQiang
School: Chinese Academy of Agricultural Sciences
Course: Agricultural Entomology and Pest Control
Keywords: The tea geometrid nuclear polyhedrosis virus Geographic populations Difference in sensitivity Genetic variation Reproductive isolation
CLC: S435.711
Type: Master's thesis
Year: 2011
Downloads: 46
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Abstract

Tea geometrid (Ectropis obliqua Prout) is one of the major pests of tea plantations in China, is widely distributed in the main tea-producing areas, especially in Jiangsu and Zhejiang and Anhui regions large, multi-generations, often resulting in a substantial cut of the tea plantations, serious economic losses. The the tea geometrid nuclear polyhedrosis virus (Ectropis obliqua Nucleopolyhedrovirus, EoNPV) is with strong pathogenicity the tea geometrid the major pathogen Enemies, tea geometrid, the advantages of having a loyal and strong, non-toxic, non-polluting, has now been developed in large scale commercial formulation. Field research in recent years, the tea geometrid populations of different tea-growing areas in China differences EoNPV sensitivity tea geometrid larvae mortality is significantly lower in some areas the virus. For clear-cut produce this phenomenon of reasons whether it is due to the different geographical populations of genetic differentiation caused by the tea geometrid different geographic populations EoNPV the difference in sensitivity and population genetic variation research, to clear tea geometrid different geographical populations of genetic differentiation and phylogenetic relationships, and thus provide a theoretical basis for scientific control tea geometrid. In this study, 11 different geographic populations tea geometrid experimental materials the, during virus sensitive bioassay based on the mitochondrial DNA CO Ⅰ and CO Ⅱ gene sequence analysis, and genetic hybridization and backcrossing test with different sensitivity to different populations for phylogenetic and genetic variation, from the molecular level and the genetic point of view to explore the tea geometrid population genetic differentiation level, analysis speculate with inherent sensitivity to differences in the level of contact. The main findings are as follows: (1) the tea geometrid 11 geographic population differences EoNPV sensitivity LC50 ratio of 724.5 times. Bioassay results, the tea geometrid 11 geographic populations have low sensitivity of the eight populations varying degrees of LC50 differences between the various groups of up to 724.5 times, low sensitivity Stocks LT50 generally 5-6 days longer. Tea geometrid difference in sensitivity of the virus and the geographic distribution of the population did not exhibit a large correlation, two populations of the same province (Hangzhou and Quzhou) may be quite different, and the geographical distribution of the two populations far (such as Yangzhou and Wuhan), with a similar degree of sensitivity. (2) based on mitochondrial DNA CO Ⅰ and CO Ⅱ gene sequence analysis, the tea geometrid 11 geographic populations of genetic differentiation exists. The the tea geometrid population mitochondrial DNA CO Ⅰ and CO Ⅱ AT two gene sequences in the average content of 70.5% and 74.5%, has AT base preferences; nucleotide substitutions vast majority occur in the first three points of the codon, mostly for synonymous substitutions, and the conversion significantly higher than transversions; higher part of the population haplotype polymorphism and nucleotide polymorphisms. CO Ⅰ and CO Ⅱ gene sequences detected a total of 42 different haplotypes, NJ and MP build two systems tree, its topology is basically the same, only different branches confidence. All the tea geometrid population is roughly divided into two groups: the strong sensitivity of Hangzhou, Yixing and Cross shop three individuals in a population haplotype performance sensitive bioassay experiments together, the remaining eight low sensitivity haplotypes of individuals in a population clustered into a class of sequence differences of the two types of inter-group up to about 5%, the sensitivity differences between populations have greater differentiation. (3) the difference in sensitivity of EoNPV two largest tea geometrid population (Hangzhou population, and Quzhou population) between reproductive isolation. Genetic hybridization and backcrossing test results show, Hangzhou and Quzhou F1 hybrids of the two populations compared to the parental hybrids showed more obvious weakness, the hybrid processing fecundity and egg hatchability were significantly reduced, larvae significantly shorten the duration, pupal weight loss, normal eclosion of adults, not normal mating and offspring breeding offspring viability decreased, also the sex ratio imbalances; the backcross test results show that the F1 generation of non-sterile female spawning selfing and backcrossing process, are not normal hatch. Therefore infer reproductive isolation between the two populations of Hangzhou and Quzhou, great possibility of mating or mating in the field under natural conditions do not produce infertile hybrids, Two Species most likely to be a different species, the difference in sensitivity may be one of the phenotypic differences caused by the differences between species.

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CLC: > Agricultural Sciences > Plant Protection > Pest and Disease Control > Crop pests and diseases and their prevention > Economic crop pests and diseases > Beverage crop pests and diseases > Tea pests and diseases
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