| Tetranychus urticae Koch is the cosmopolitan harmful mites with wide host rangeand the widest range of food,the one of the most severely harmful agricultural mites。It has been emerged a major population of pests.Because of the use of high doses andhigh frequency of pests,it has quesed the T.urticae to become resistant.On the basis of resistance breeding and selection in laboratory. The populationwas tested every five generations by slide-dip method and LC-P line wasreceived.Studied the resistance tendency of Tetranychus urticae Koch toFenpropathrin and Spirodiclofen.Analysised the resistance decline and recoverydynamic of etranychus urticae Koch to Fenpropathrin and Spirodiclofen,and theresistance risk were analyzed with the resistance reality heredity.Providing a referenceto molecular detection of resistance and resistance management strategy.The papercincludes as follows:1. Resistance risk assessment of Tetranychus urticae (Koch) to two acaricidesThe effects of retarding resistance evolution of mixing and alternating useof acaricides were studied based on the resistance selection of2acaricides toTetranychus urticae in the laboratory. And by using the threshold trait analysisin quantitative genetics,this paper studied the realized resistance heritability of Tetranychus urticae to fenpropathrin,spirodiclofen and spirodiclofen-fenpropathrinmixture,and predicted the resistance risk of Tetranychus urticae to these three acaricides.After20-generations of selection with fenpropathrin,spirodiclofen and spirodiclofen-fenpropathrin mixture,the resistance of Tetranychus urticae to the three acaricides increased by44.93,11.34and40.90-fold,and the realized resistance heritability was0.2366,0.1233and0.2210,respectively. Analysis of resistance selection and estimation of realized heritability of resistance to each of or twomixed acaricides showed that Fenpropathrin has higher resistance risk than spirodiclofen in Tetranychus urticae.The mixture of fenpropathrin-spirodiclofen would slow resistance development compared with a sequence the single use of fenpropathrin followed by spirodiclofen.2. Studies on the resistance tendency of Tetranychus urticae (Koch) toFenpropathrin and SpirodiclofenThe result showed that the resistance of the two resistant strains was all instable, but theirdepression rates were different.After R-F were selected for8generations respectively, theirresistance decreased to one third of the original level.Then the resistance depressed slowly.Andafter the strains were selected for16generations, their resistance decreased by94.14%.Comparing with the R-F strains,the resistance depression of R-S strains wereslower. Through equation fitting ofresistance depression tendency, it was found that the resistancedepression of the two strains was both in line with quadratic curve model.The results of theequation fitting of resistance recovery tendency showed that resistance recovery of the two strainswas quite different, and the fitting curve of R-F strain was in line with the logistic model, whilethat of R-S strainwas in line with quadratic curve model.3. Microsatellite DNA polymorphism in Resistant strains of the Tetranychusurticae (Koch)Microsatellite DNA polymorphism in a susceptible and four resistant strains (Fenpropathrin-,Clofentezine-，Sirotetramat-, and Pyridaben-resistant strains) ofTetranychus urticae (Koch) were evaluated using two microsatellite DNA primers. The results showed that distinct microsatellite DNA polymorphism was detected in the four resistant strains. Five strains were distinctly separated at the similarity level of0.80by primer Tu11,and at the similarity level of0.70by primer Tu1. Microsatellite DNA polymorphism cannot determine the locations of r esistant genes, but with the help of NTSYS PC Versio n2.10e,the results can provide guidance for establishing a rapid method for detection the resistance inTetranychus urticae (Koch),which is helpful to resistance monitoring and resistance management in the field. |
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