| Sogatella furcifera（horváth）and Laodelphax striatellus（Fallén）are important pests to rice production in China.Chemical insecticides are important methods to prevent and control the outbreak of the two planthoppers.However,due to long-term unreasonable use of chemical pesticides,they have developed different degrees of resistance to a variety of pesticides.In order to clarify the resistance status of two species of planthopper to common insecticides in China,we montiored the resistance status of white-backed planthopper（WBPH）and small brown planthopper（SBPH）populations in different areas to common insecticides in 2020.Buprofezin used to be an important insecticide for rice planthopper control in the field.However,the resistance to buprofezin of small brown planthopper developed very quickly.Now,it has developed moderate to high levels of resistance in the field.Therefore,this paper aims to explore the inheritance mode and biochemical mechanism of resistance to buprofezin in the small brown planthopper and provide help for field resistance management.1.Resistance monitoring of S.furcifera in 2020In this study,we monitored the resistance of 6 field populations of S.furcifera to 8commonly used insecticides which collected from Fujian,Sichuan,Jiangsu and Yunnan provinces by rice stem seedling dipping method in 2020.The results showed that all the monitored populations exhibited moderate to high resistance to buprofezin（RR=35.3-183.6）,and only FQ20 population reached high resistance.All populations showed sensitive to moderate resistance level to chlorpyrifos（RR=0.1-31.3）,only TC20population in Yunnan was very sensitive.For pymetrozine,all populations developed sensitive to moderate resistance level（RR=1.5-20.5）,and 33.3%populations reached moderate resistance level.All monitored populations kept sensitive to moderate levels of resistance to the neonicotinoids imidacloprid,thiamethoxam,and dinotefuran（RR<14.7）,among which 66.7%populations exhibited moderate level resistance to imidacloprid and16.7%exhibited moderate level resistance to thiamethoxam and dinotefuran.All the monitored populations showed sensitive to low levels resistance to sulfoxaflor（RR=0.3-8.7）,and only TZ20 population deveolped low levels resistance.All the monitored populations in 2020 kept susceptible levels to triflumezopyrim（RR=0.1-1.9）.2.Resistance monitoring of L.striatellus in 2020In this study,we monitored the resistance of 4 field populations of Laodelphax striatellus to 8 commonly used insecticides which collected from Jiangsu,Anhui and Zhejiang provinces by rice seedling dipping method in 2020.The results showed all the monitored populations exhibited moderate to high resistance to buprofezin（RR=26.5-119.6）,and half of them had reached high resistance level;all populations showed moderate resistance level to chlorpyrifos（RR=19.7-40.1）;all populations kept sensitive for pymetrozine（RR=1.2-1.9）,For the neonicotinoids thiamethoxam,nitenpyram,sulfoxaflor and triflumezopyrim,they were all kept sensitive（RR<4.0）,but the resistance level to dinotefuran was low to sensitive（RR=3.0-6.4）,and half of the monitored populations had developed moderate resistance.3.Resistance inheritance mode of L.striatellus to buprofezinIn order to explore the genetic characteristics of resistance to buprofezin of L.striatellus,rice seedling dipping method was used to determine the dose-response data of resistant and sensitive parents,reciprocal crosses（F1、F1’）,self-cross（F2）and backcross（BC）progenies of the third instar nymphs to buprofezin.The results showed that reciprocal crosses（F1、F1’）had 110.3 and 157-fold resistance to buprofezin and LC95%confidence line overlap,respectively,which indicated that the resistance was autosomal;the dominance of the reciprocal crosses was 0.07（F1）and 0.15（F1’）,respectively,indicating that the resistance was incomplete dominance.LC-P lines of self-crossing progeny and back-cross progeny were significantly different from corresponding expected curves assuming buprofezin inheritance,fit test results further showed no agreement with the single-gene hypothesis,suggested that buprofezin resistance s controlled by two or more alleles.In conclusion,the resistance to buprofezin of L.striatellus was found to be polygenic,autosomal and inherited as a incomplete dominance trait.4.The synergist experiment of L.striatellus to buprofezinIn order to explore the metabolic resistance mechanism of L.striatellus to buprofezin,rice seedling dipping method was used to determine the synergistic effects of detoxification enzyme inhibitors piperyl butyl ether（PBO）,diethyl maleate（DEM）and triphenyl phosphate（TPP）on buprofezin.The results showed that the three detoxification enzyme inhibitors had no significant synergistic effects on the two field-resistant populations of L.striatellus（SR<1.3）,it is suggested that metabolic enzyme mediated detoxification plays a limited role in the formation of buprofezin resistance. |
