| The rice stem borer,Chilo suppressalis(Walker)(Lepidoptera:Pyraidae)is an important pest on rice.For a long time,the prevention and control of C.suppressalis mainly rely on chemical control.The insecticides includes monosultap,chlorpyrifos and triazophos,abamectin and emamectin benzoate,chlorantraniliprole,flubendiamide and the mixture of these insecticides.However,due to the long-term and abuse of chemicals,there are many reports on control efficacy reducing and pest resistance developing.In order to design the resistance management strategy to control the rice stem borer effectively,we monitored the resistance of field populations to the above seven agents,and the resistance mechanism of C.suppressalis to diamides was explored on the target mutation.1.Resistance monitoring to seven insecticides in C.suppressalisIn this study,the resistance of 37 populations of rice stem borer,which collected from 23 provinces in China,to chlorpyrifos,triazophos,abamectin,emamectin benzoate,monosultap,chlorantraniliprole,flubendiamide by rice seed dipping method or tropical method were determined in 2015-2016.The results showed that there were obvious geographical differences in the resistance level of C.suppressalis populations to these seven kinds of insecticides.The population of C.suppressalis from Zhejiang,Jiangxi and Hunan province was more resistant,while the population in Jiangsu and Sichuan Province was relatively sensitive.In 2015-2016,13 populations were found to be low to moderate level resistance to chlorantraniliprole(RR = 7.1-74.0-fold),38.2%of the monitored population.Among them,XJ15,XS16,YY15,YY16,CN15,CN16 and Jiangxi NC15 and NC16 had reached moderate resistance(RR = 10.9-74.0-fold).The highest resistance in Zhejiang CN16 population was 74.0-fold to that of flubendiamide,and the population of CN15 and CN16 rice stem borer had reached 138.4-fold and 107.6-fold high resistance to flubendiamide.Zhejiang XS15,YY15,JH16,Jiangxi NC15 and Hubei JL15 reached moderate resistance to flubendiamide(RR = 16.7-85.1-fold),25.0%of the monitored population.The resistance to chlorantraniliprole in Zhejiang Cangnan,Yuyao,Xiangshan and Jiangxi Nancheng was significantly higher than that in 2014(RR = 8.9-77.6-fold).In 2015-2016,18 field populations had reached moderate resistance to abamectin(RR = 11.6-94.1-fold),64.3%of the monitored populations and he resistance ratio increased significantly in 2016 compared with that in 2015.80.0%of the populations were susceptible to emamectin benzoate,the highest resistance one was RA16 population in Zhejiang(RR = 7.7-fold).22 population showed low to moderate level of resistance to chlorpyrifos(RR =5.0-35.0-fold)which accounted for 88,0%of monitored populations,and the highest resistance population is Zhejiang XS16 population(RR = 35.0-fold),From 2015 to 2016,the resistance level of monosultap and triazophos were significantly decreased in the field compared with that before 2012.For monosultap,83.3%of the monitored population were in susceptible level,and the highest resistance was Hunan DA 16 population(RR ?11.5-fold).For triazophos,10 populations were susceptible or low resistance and 13 populations were in moderate resistance level,the highest population was detected in SG16(RR= 87.1-folds).2.Study on the resistance molecular mechanism of C.suppressalis to diamides insecticidesIn order to understand the resistance mechanism of csuppressali.to diamides,this study refers to the position of the mutantion I4790M,which has been found in Plutella xylostella and Tuta absoluta.The results showed that the ATA mutation at position 4753 was ATG(I4753M),and the frequency of mutation at the point of resistance to chlorantranuliprole-resistant population of Xiangshan in Zhejiang province and a susceptible populations were detected,showing that the mutation frequency of resistant population exceeded 90%,while the mutation was not found in susceptible population.It is speculated that the I4753M mutation may be related to the resistance of the population of C,suppressalis to diamides. |
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