Resistance Monitoring And Insecticides Screening For Control Three Rice Planthoppers In Nanjing Area

Rice planthoppers are important pests in rice production in China,there are mainly three kinds of rice planthoppers which damage the rice,Laodelphax striatellus(Fallen),Sogatella furcifera(horvath)and Nilaparvata lugens(Stal).Three kinds of rice planthoppers in the host range and the harm period are different,and the resistance ratios of rice planthoppers to the same insecticide also exist obvious difference.To use insecticides scientifically for control rice planthoppers,we detected the resistance of three planthoppers in Nanjing area in this study.Combined with the results of resistance monitoring,we carried out trial efficacy of dinotefuran,nitenpyram,imidacloprid,pymetrozine,sulfoxaflor,chlorpyrifos,thiamethoxam and flonicamid.The main results are as follows:??Resistance monitoring of three species of rice planthoppers1.The resistance monitoring of small brown planthopper to six insecticides showed that field populations monitored were at moderate resistance levels to chlorpyrifos,sensitive or low level of resistance levels to thiamethoxam,nitenpyram,pymetrozine,acetamiprid,dinotefuran and sulfoxaflor,and there was no obvious change in the resistance ratios of the same insecticide between 2014 and 2015.2.The white back planthopper has reached the moderate level of resistance to buprofezin and chlorpyrifos,pymetrozine,and resistance ratio of buprofezin increased rapidly,in 2015 has reached 93.6-fold;and resistance ratio of chlorpyrifos and pymetrozine has declined,in 2015 has reached 26.6-fold and 17.4-fold,S.furcifera was sensitive to imidacloprid,thiamethoxam,dinotefuran and sulfoxaflor,and there was no significant change in two years.3.The resistances of brown planthopper to imidacloprid,buprofezin,pymetrozine and thiamethoxam are relatively high,among them,resistance of imidacloprid(537.4)and buprofezin(305.1)still kept extremly high level,the resistance to thiamethoxam has increased significantly from the moderate level in 2014(83.0)to high level in 2015(244.5).But the resistance to pymetrozine decreased from a high level of resistance in 2014(155.8)to a moderate level of resistance in 2015(57.9).In addition,the resistance of N.lugens in the Nanjing area to chlorpyrifos,nitenpyram and dinotefuran increased gradually over the past two years,the resistance to nitenpyram(7.7)was at low level and the resistance to chlorpyrifos,sulfoxaflor and dinotefuran reached the moderate level,there was no significant change in resistance to flufiprole(14.5-13.8).??Screening of high efficient insecticides to control rice planthoppers1.The following insecticides were used to control the white planthopper in 2015:pymetrozine · chlorpyrifos 50%SC,pymetrozine 50%WP,chlorpyrifos 40%EC,nitenpyram 50%SP,dinotefuran 20%SG,imidacloprid 10%WP,thiamethoxazole 25%WG,sulfoxaflor 22%SE.The results showed that the field efficiency of pymetrozine · chlorpyrifos 50%SC,nitenpyram 50%SP,dinotefuran 20%SG,and sulfoxaflor 10%WG could control more 91.21%after 15 days under recommended dosage.After 5 days,the control effect of chlorpyrifos 40%EC could reach to 92.77%,however,after 10 days,the control effect decreased gradually,the period of validity was shorter than pymetrozine 50%WP,sulfoxaflor 10%WG and neonicotinoids.The quick effect of pymetrozine 50%WP is not good,but its duration can be up to more 15 days.In paddy fields with whitebacked planthopper as the main pest,it is recommended to use amount of 20 mL/667m2 Of pymetrozine · chlorpyrifos 50%SC,8 g/667m2 of nitenpyram 50%SP,30 g/667m2 of dinotefuran 20%SG,40 g/667m2 sulfoxaflor 10%WG;pymetrozine 50%WP has a slower speed and long duration,it is recommended to use with quicker products;imidacloprid 10%WP and thiamethoxazole 25%WG have good quick efficacy,but the late insect control effect is not good,they are recommended to be mixed with pesticides with long duration and other mechanisms;the control effect of sulfoxaflor 22%SE is not good enough,and it is not recommended to use alone.2.The following insecticides were used to control N.lugens in 2015:pymetrozine · chlorpyrifos 50%SC,dinotefuran 20%SG,thiamethoxam 25%WG,nitenpyram 50%SG,metolcarb 25%WP,sulfoxaflor 10%WP,pymetrozine · thiamethoxam 30%SE.The results showed that it is recommended to use 30 g/667m2 of dinotefuran 20%SG,4 g/667m2 of thiamethoxam 25%WG,8 g/667m2 of nitenpyram 50%SP,40 g/667m2 of sulfoxaflor 10%WP,20 mL/667m2 of pymetrozine · thiamethoxam 30%SE,these insecticides have good quick-acting and long duration with the control effects of(80.25-92.4%)after 3 days and(92.23-93.28%)after 14 days;metolcarb 25%WP have good quick efficacy and bad duration,the quick effect of pymetrozine 50%WP is not good,but its duration is long;the two kinds of pesticides in the use are suggested to use rationally with other mechanisms pesticides.To sum up the results of the two experiments on the control of S.furcifera and N.lugens,it is obvious that both of them have obvious commonality in prevention:The best period of treatment was the peak of young nymphs;When spraying,it is necessary to ensure uniform spray and the liquid can be poured into the lower part of the rice plant,the control effect of S.furcifera and N.lugens was very good to use 8 g/667m2 of nitenpyram 50%SG,30 g/66m2 of dinotefuran 20%SG,40 g/667m2 of sulfoxaflor 10%WP;the control effect of S.furcifera was very good to use 20 mL/667m2 of pymetrozine · chlorpyrifos 50%SC,and the control effect of N.lugens was very good to use 20 mL/667m2 of pymetrozine· thiamethoxam 30%SE.