Comparative Of Diamide Insecticides Resistance In Diamondback Moth Between Laboratory Selection Strains And Field Collection Populations

The diamondback moth（DBM）,Plutella xylostella（L.）,is the most widely distributed major pest.There are more than 40 species of host plants,which mainly damage cruciferous vegetables.Because of its high fecundity,overlapping generations,and the frequent use of some areas of production,resulting in a variety of insecticide resistance.The problem of resistance to diamondback moth is a serious threat to the production of cruciferous vegetables.Diamide insecticides as a new type of ryanodine receptor（RyR）activation of insecticide on Lepidoptera and high efficiency,low toxicity to mammals and safe,can make effect on insect ryanodine receptor calcium release channel regulation remains open,sustained calcium release will cause the body to shrink,vomiting,and manure,then stop eating,resulting in insect death.With the application of the double amide pesticide,the problem of the pest resistance to the insecticide has been paid more and more attention.In order to study the mechanism of resistance of diamondback moth to diamide insecticides,research through laboratory resistance selection,analysis of the risk of resistance of diamondback moth to diamide insecticides;at the same time relative to the susceptible strains,diamide resistant strains and field resistant populations as materials,the research of ryanodine receptor（RyR）the relative expression,is to provide guidance for the scientific use of pesticides.The main results are as follows:1.On the basis of early resistance studies,the toxicity of 3 instar larvae of Plutella xylostella to double amide insecticides was determined by dropping method.The results show that the chlorantraniliprole resistant diamondback moth screening to the 46 generation,the LD₅₀0 was 595.36μg/g,the resistance ratio 684.54,the selection of resistance to early resistance development is relatively slow,the later has been in a rising stage;on flubendiamide resistance screening of diamondback moth to the 36generation,LD₅₀ 623.75μg/g,the resistance ratio 677.25,diamondback moth to flubendiamide resistance breeding of early resistance development is relatively slow,late has been in the rising stage.2.The cross resistance test results showed that the virulence of cyantraniliprole,,chlorfenapyr,tebufenozide,indoxacarb and chlorantraniliprole resistant strains have certain cross resistance cyantraniliprole and flubendiamide,no cross resistance to other three reagents;flubendiamide resistant strains have cross resistance to some of the cyantraniliprole,no cross resistance to other four kinds of chemicals.3.The expression of diamondback moth ryanodine receptor gene in different strains were determined by fluorescence quantitative PCR.The experimental results show that the relative expression of sensitive strains was 1,with two diamide resistant strains of resistance ratio increased,the expression of ryanodine receptor is higher than that of susceptible population,and gradually increased;resistance change two field resistant populations of diamide insecticides is relatively stable,the expression of ryanodine receptor was higher than that of the S strain,but the expression level of RyR gene is relatively stable,no obvious linear relationship between generations,the resistance ratio.This shows that the relative expression of causes of diamondback moth resistance to diamide insecticides and ryanodine receptor associated with increased.4.Different strains of the diamondback moth multifu nctional oxidase and glutathione S-transferase,determination of esterase activity,the enzyme activity of three enzymes relative to susceptible strains was 1,two diamide insecticides resistant strains and two field resistant populations are relatively sensitive population 2.251–fold,1.18-fold,0.99-fold and 1.05-fold respectively;glutathione S-transferase is relatively sensitive population of 1.05-fold,1.02-fold,1.03-fold and 1.03-fold respectively;esterase is relatively sensitive population 1.42-fold,1.17-fold,0.97-fold and 1.05-fold.The results showed that the resistance of the diamondback moth to the formation of the double amide pesticide was related to the function of the multifunctional oxidase and esterase.