Insecticide Resistance Monitoring Of Brown Planthopper In 2020 And The Susceptibility Of NAChRs Mutants Drosophila To Eight Insectcides

The brown planthopper（Nilaparvata lugens）is an important pest that damages rice production in China,and it has been included in the"List of Crop Pests and Diseases"by the Ministry of Agriculture and Rural Affairs.Chemical control is the main method to prevent the occurrence of brown planthoppers.However,due to the frequent and unreasonable use of pesticides,the problem of brown planthopper resistance has become more serious.Therefore,clarifying the resistance of brown planthoppers can provide a basis for the selection of pesticides and resistance management of brown planthoppers in the field.At present,the pesticides for controlling brown planthoppers are mainly act on nicotinic acetylcholine receptors,such as nitenpyram,dinotefuran,sulfoxaflor and triflumezopyrim,etc.,however these agents act on the specific subunit of the acetylcholine receptor is unknown.Therefore,this study intends to use a bioassay method to monitor the resistance level of the brown planthopper in China,and use reverse genetics technology to determine that the toxicity of 8 insecticides that act on the receptor nicotinic acetylcholine receptor against mutantions of Drosophila.The specific research results of the sensitivity to insect agents are as follows:1.Insecticide resistance monitoring of brown planthopper in 2020In order to clarify the current status of brown planthopper resistance in China in2020,the rice stem dipping method was used to monitor the resistance of 30 brown planthopper field populations in 11 provinces（cities）in China.The results showed that71%of field populations had reached a high level of resistance（150.2-550.4 fold）for pymetrozine;for triflumezopyrim,all the populations of brown planthoppers monitored in the field are at a sensitive level（1.3-3.8 fold）;for nitenpyram,except for the population of Mangshi,which is at a sensitive level（4.9 fold）,the remaining populations of brown planthoppers are at a low level to moderate level resistance（6.2-47.3 fold）;for dinotefuran,the monitored field brown planthopper populations are at a moderate to high level of resistance（10.9-263.6 fold）,and about 62%of the populations have reached high levels of resistance;for chlorpyrifos,82%of the brown planthopper populations in the field have reached a moderate level of resistance（11.8-64.5 fold）;for chlorpyrifos,except for the Dafeng population（8.6 fold）,which has a low level of resistance,the remaining populations are all at a moderate level resistance（15-41.1fold）;the brown planthopper population in the field is at a moderate to high level of resistance to ethiprole（44.2-360.6 fold）;for pesticides that have been suspended,the field brown planthopper population is still maintain a high level of resistance to thiamethoxam（227.4-2261.7 fold）,imidacloprid（2583.8-6272.7 fold）and buprofezin（588.5-5622.3 fold）.2.The susceptibility of nAChRs mutants Drosophila to eight insectcidesIn order to clarify the effect of the deletion of different nAChRs subunits on the sensitivity of insecticides acting on this receptor,the model organism Drosophila melanogaster was used to determine the sensitivity of different nAChRs subunit mutants to nAChRs regulators.The test results showed that among the 9 nAChRs mutant flies,the resistance of Dβ1^attp and Dα1^attp mutants to triflumezopyrim was 13.0fold and 10.9 fold,respectively,compared with the control.To imidacloprid,the Dα6^attpmutant had the highest resistance（19.4 fold）,followed by the Dα1^attp and Dα5^attpmutants,which were 5.2 and 7.1 fold,respectively.To dinotefuran,the Dα7^attp mutant has the highest resistance（5.2 fold）,and the other mutants have less resistance changes（1.4-2.9 fold）.All mutant flies are less sensitive to thiamethoxam（1.4-2.7 fold）,nitenpyram（1.5-3.1 fold）and sulfoxaflor（1.3-2.9 fold）.For spinosyn and spinetoram,the Dα6^attp mutant was significantly higher than the control by 22.8 fold and 50.2 fold,respectively.In addition,the resistance of Dα2^attp,Dβ1^attp,and Dβ3^attp mutants to spinetoram was also significantly higher than that of the control.They are 9.9 fold,10.7fold,and 14.8 fold respectively.