Molecular Mechanism Of The Brown Rice Planthopper,Nilaparvata Lugens(st(?)l) In Response To Nitenpyram And Chlorpyrifos Stress

The brown planthopper（BPH）,Nilaparvata lugens（St（?）l）（Hemiptera:Delphacidae）is one of the most important pests on rice,widely distributed in China and many Asian countries,with sudden and violent characteristics,and could migrate long distances.At present,the control of brown planthopper still mainly relies on chemical insecticides.However,field populations of N.lugens have developed varying levels of resistance to34 active ingredients with insecticidal activity due to the long-term irrational use of insecticides.Nitenpyram and chlorpyrifos are important insecticides for controlling N.lugens in rice production,but N.lugens has developed moderate levels of resistance to both insecticides.Therefore,there is an urgent need to assess the risk of resistance to insecticides in N.lugens and to identify detoxification metabolism genes in response to nitenpyram and chlorpyrifos stress.It is important to identify the detoxification metabolism genes of N.lugens against nitenpyram and chlorpyrifos.And to reveal the molecular mechanism of response to nitenpyram and chlorpyrifos stress in brown planthopper for scientific use of insecticides,effective control of insect pests,delay of resistance development and protection of ecological environment.Based on this study,we investigated the activities of three detoxification metabolism enzymes and the expression of genes of five detoxification metabolism enzymes in the N.lugens treated with sublethal and lethal concentrations of nitenpyram and chlorpyrifos to reveal the response of N.lugens to the two insecticide stresses and the molecular mechanisms.The main results are listed as follows:1.The LC₁₀,LC₃₀,LC₅₀ and LC₇₀ of nitenpyram to nitenpyram-resistant strain of N.lugens were 129.24 mg/L,259.75 mg/L,421.25 mg/L and 683.15 mg/L,respectively;and the LC₁₀,LC₃₀,LC₅₀ and LC₇₀ of chlorpyrifos to nitenpyram-resistant strain of N.lugens were 13.12 mg/L,18.96 mg/L,24.46 mg/L and 31.56 mg/L,respectively.The LC₁₀,LC₃₀,LC₅₀,and LC₇₀ of nitenpyram to nitenpyram-susceptible strain of N.lugens were 0.03mg/L,1.46 mg/L,4.33 mg/L,and 12.83 mg/L,respectively;the LC₁₀,LC₃₀,LC₅₀,and LC₇₀ for chlorpyrifos in nitenpyram-susceptible strain of N.lugens were 0.64 mg/L,1.68mg/L,3.30 mg/L and 6.45 mg/L,respectively.2.The nitenpyram-resistant and susceptible strains of N.lugens were treated by sublethal and lethal concentrations of nitenpyram and chlorpyrifos,respectively.It was found that an increase in enzyme activity in resistant and susceptible brown planthopper was induced treated with LC₁₀ of nitenpyram and chlorpyrifos.The stress of LC₃₀,LC₅₀and LC₇₀ with nitenpyram and chlorpyrifos induced an increase in enzyme activity of P450s,Car Es and GSTs in resistant and susceptible N.lugens first,and then the enzymatic activity of P450s,Car Es and GSTs was inhibited.3.The expression of detoxification metabolic genes such as P450s,Car Es,GSTs,UGTs and ABCs in brown planthopper were analyzed by q RT-PCR when they were treated with sublethal and lethal concentrations of nitenpyram and chlorpyrifos.The result showed that P450 genes CYP4G76,CYP4CE1,CYP417A3,CYP6ER1,CYP6CS1;Car E genes Nl Car E1,Nl Car E2,Nl Car E16,Nl Car E19,Nl Car E25,Nl Car E29;UGT genes UGT-2A3,UGT-2B9,UGT-1-3;GST genes Nl GSTd2,Nl GSTe1,Nl GSTt1,Nl GSTo1,Nl GSTs3;and ABC transporter protein genes Nl ABCB8,Nl ABCC3,Nl ABCD could be induced up-regulated expression in N.lugens nitenpyram-resistant and susceptible strains,suggesting that the expression of these genes may be associated with N.lugens resistance to nitenpyram and chlorpyrifos.Through the above study,we will reveal the molecular mechanism of the response of N.lugens to the stress of nitenpyram and chlorpyrifos,and lay the theoretical foundation for the rational and scientific use of nitenpyram and chlorpyrifos and the in-depth research on the function of the detoxification genes of N.lugens.