| Frankliniella occidentalis,Frankliniella intonsa,Odontothrips loti and Sussericothrips mililotus are the dominant populations of Alfalfa thrips in Yinchuan area,which occur in 100%of alfalfa planting areas in China,causing serious harm to alfalfa.In this study,four species of thrips in alfalfa field in Yinchuan area were selected as the research objects,and their resistance mechanism was preliminarily discussed.In addition,the toxicity of 19 common insecticides to Frankliniella intonsa was determined,and the synergistic effects of insecticides mixed with different mechanisms and auxiliary agents were studied,which provided theoretical basis for resistance management and pesticide control of Frankliniella intonsa.The main research results are as follows:1.Impregnation method and drug film method were used to monitor the resistance of 4 species of Thrips population in Yinchuan field to 7 classes and 10 kinds of insecticides.The results showed that the resistance level of Frankliniella occidentalis population in Yinchuan area was the strongest.The resistance levels to acetamiprid,deltamethrin,imidacloprid and bifenthrin were high,with resistance ratios ranging from 50.60 to 121.57 times,and the resistance levels to cyantrandiamide,bromenitrile,spinosad and abamectin were medium,with resistance ratios ranging from 10.10 to 34.04 times.The resistance levels to ethyl polypastetin and ethyl snail were low,and the resistance ratios were 6.61 times and 9.70 times.The resistance level of Frankliniella intonsa was second,and the resistance levels to bifenthrin and acetamiprid were 50.94 times and 67.57 times,respectively.The resistance to deltamethrin,imidacloprid,brometronil and cybroandiamide was moderate,with resistance ratios ranging from 10.97～33.79 times,respectively.The resistance levels to spinosad and avermectin were low,with resistance ratios of 5.14 and 6.90 times.The sensitivity to snail ethyl ester was decreased,and the resistance ratio was 3.99 times.The resistance ratio was 2.59 times.Odontothrips loti and Sussericothrips mililotus resistance level is relatively low,of biphenyl chrysanthemum ester,bromine cyanide worm amide,imidacloprid,deltamethrin resistance ratio between 10.02-44.50 times,the bromine worm nitrile,abamectin,sterilization element,screw ethyl acetate and ethyl sterilization element in a sensitive state or lower resistance level,resistance ratio between 9.91～1.12 times.2.The results of enzyme activity determination of different field populations of Alfalfa thrips showed that the activities of carboxylesterase,glutathione S-transferase,multifunctional oxidase and acetylcholinesterase in field populations of Frankliniella occidentalis,Frankliniella intonsa and Odontothrips loti were all higher than those in field populations of Sussericothrips mililotus.In vivo synergistic test results showed that TPP and PBO showed significant synergistic effects on ethyl polyfungides,while DEM showed a slightly lower synergistic effect on ethyl polyfungides,with a synergistic ratio of 2.00 times.The results indicated that carboxylesterase and multifunctional oxidase played important roles in the resistance of Frankliniella intonsa to ethylpolysadicin,and glutathione S-transferase also played a role in the resistance of Frankliniella intonsa to ethylpolysadicin in field populations.TPP showed significant synergistic effect on snail ethyl ester,PBO showed a slightly lower synergistic effect,DEM showed no obvious effect on snail ethyl ester.These results indicated that carboxylesterase and multifunctional oxidase played important roles in ethyl snail resistance in Frankliniella intonsa,while glutathione S-transferase did not play an obvious role in ethyl snail resistance in Frankliniella intonsa.TPP showed significant synergistic effect on chlorpyrifos,and the synergistic ratio of TPP to chlorpyrifos was 2.14 times in each field population of Frankliniella intonsa.PBO and DEM also had a certain synergistic effect on chlorpyrifos,but it was not significant,the synergistic ratio was only 1.36 times and 1.25 times.These results indicated that carboxylesterase played an important role in chlorpyrifos resistance in Frankliniella intonsa,and multifunctional oxidase and glutathione S-transferase also played a certain role in chlorpyrifos resistance in field populations of Frankliniella intonsa.3.The combined effects of thiamethoxam and 18 insecticides on adults of Frankliniella intonsa were determined by impregnation method and drug film method in laboratory.The results showed that the combination of thiamethoxam and emamectin benzoate,chlorfenapyr,chlorpyrifos(effective component 1:1)had a stronger synergistic effect on Frankliniella intonsa,and the co-toxicity factors were 147.49,138.86 and 91.98,respectively.The results of optimal ratio screening showed that thiamethoxam,emamectin benzoate,chlorfenapyr and chlorpyrifos had the best synergistic effect with the ratio of effective component 1:4,and the co～toxicity coefficient reached 749.59,572.78 and 214.56,respectively,showing significant synergistic effect(P<0.05);The results of field efficacy test showed that the compound combination of[thiamethoxam+emamectin benzoate(1:4)]had obvious synergism effect on the control of Frankliniella intonsa,and the control effect was up to 92.23%,which was 3.22%～9.61%higher than that of thiamethoxam agent.It was the best compound combination for the control of Frankliniella intonsa in the field,and had high application value.4.Synergistic effects of insecticides and auxiliaries on Frankliniella intonsa,the following conclusions:nano controlled release agent and times gen of thiamethoxam,stimulated the healthy of fluorine organism worm amine nitrile has significant synergistic effect,the field test shows that after applying pesticide control effect of each process were presented first increases,then slowly declining trend,overall distribution of combination[fluridifenitrile 30%+jijian],[thiamethoxam 40%+beichuang]and[thiamethoxam+30%nano controlled release agent]reduction effect is most obvious.These combinations can be used as the best control agents,not only to reduce the use of pesticides and thus reduce the pollution to the environment,but also to effectively control Frankliniella intonsa when used in rotation with other mechanisms of insecticides,and reduce the development of drug resistance.5.The toxicity of 19 insecticides to Frankliniella intonsa was determined.The results showed that 60%spinetoram solution and 480g/L chlorpyrifos showed high toxicity to adults of Frankliniella intonsa,with LC50 values of 0.03mg/L and 0.15mg/L,respectively.The toxicity of the 19 insecticides was as follows:spinetoram solution>chlorpyrifos>spinosad>spirotetramat>fluridifenitrile>chlorfenapyr>germine diacetare>thiamethoxam>azadirachtin>matrine>flupyradifurone>cyantraniliprole>emamectin benzoate>fufenozide>abamectin>acetamiprid>imidacloprid>bifenthrin>chlorfenapyr. |
PDF Full Text Request