Insecticide Resistance And Insecticide-Mixture For Two Planthoppers, Sogatella Furcifera And Laodelphax Striatellus

Sogatella furcifera and Laodelphax striatellus are both important agricultural pests in China, the former has the ability of migrating, while the latter can cause great loses not only in rice, but also in wheat. The two pest insects can damage the plants by feeding, oviposition and transmitting the virus, however, the main measure in agriculture was chemical control. Given this, the study was carried out to monitor the resistance of the two planthoppers for some conventional insecticides in 2012 and 2013. The insecticides for Sogatella furcifera include imidacloprid, thiamethoxam,. buprofezin, chlorpyrifos and isoprocarb. The insecticides for Laodelphax striatellus are thiamethoxam, nitenpyram, chlorpyrifos and pymetrozine. Moreover, the strains of Sogatella furcifera were selected by buprofezin and imidacloprid were got in our laboratory, and then cross-resistance and synergist experiments were done; Finally, we made some insecticide-mixtures for controlling white-backed planthopper and small brown planthopper.1、Insecticide susceptibility of Sogatella furcifera to imidacloprid, thiamethoxam, chlorpyrifos, buprofezin and isoprocarbDuring 2011-2013, the resistance level of White-backed planthopper against imidacloprid were so low, only few locations reached the medium resistance, besides,there existed a phenomenon of decrease. As well as the resistance against imidacloprid, the resistance level against thiamethoxam were so low that most parts were in a state of susceptibility. On the country, the resistance level of Whited-backed planthopper against buprofezin and chlorpyrifos were so high that some strains had reached high level resistance, and the resistance were developing fast. However, the White-backed planthopper remained susceptible against isoprocarb. At the same time, there exists the difference of insecticide resistance in time and location.2、Insecticide susceptibility of Laodelphax striatellus to thiamethoxam, nitenpyram, chlorpyrifos and pymetrozineIn 2012 and 2013, among 13 locations and 4 provinces, the resistance level of Laodelphax striatellus against thiamethoxam, nitenpyram was susceptibility(RR<3.0 fold), against chlorpyrifos and pymetrozine was moderate resistance to high resistance(RR=10.3-61.0 fold)and susceptibility to decreased susceptibility(RR< 5.0 fold), respectively. At the same time, there exists the difference of insecticide resistance in time and location.3、The cross-resistance of the selected Sogatella furcifera strain of imidacloprid and buprofezin to some conventional insecticidesThe Im-R strain exhibited 10.4-fold resistance to imidacloprid under the discontinuous selection with imidacloprid for 27 generations. Compared with S-NN strain, the Im-R strain showed none resistance to thiamethoxam, acetamiprid, nitenpyram, chlorpyrifos, isoprocarb and buprofezin. The Bu-R strain exhibited 15.1-fold resistance to buprofezin under the discontinuous selection with buprofezin for 35 generations. Compared with S-NN strain, the Bu-R strain showed none resistance to thiamethoxam, acetamiprid, nitenpyram, chlorpyrifos and isoprocarb. But, unlike Im-R strain, the Bu-R strain showed low-level cross-resistance (3.1-fold) to imidacloprid.4、The tentative study on mechanism for the resistant strain for imidacloprid and buprofezin of Sogatella furciferaThe synergistic effect of PBO, TPP and DEM with buprofezin and imidacloprid against TH-S strain, Im-R strain and Bu-R strain was tested. Unfortunately, no synergism was seen among these strains, which means esterase, glutathione and P450-monooxygenases may be not responsible for the metabolism in resistance.5、The insecticide-mixture for controlling Sogatella furcifera and Laodelphax striatellusThe co-toxicity of pymetrozine mixed with buprofezin, pyridaben and nitenpyram in the ration of 1:5,1:2 and 1:7 was 274.5,117.8 and 161.7 by rice stem dipping method against third instar nymphae of the white-backed planthopper, respectively. There was a synergism effect on buprofezin and nitenpyram, while an added effect on pyridaben. The co-toxicity of butene-fipronil mixed with pymetrozine in the ratio of 1:1 was 528.425 by rice-seedling method against third instar nymphae of the small brown planthopper, with the lowest LC50 of 0.599mg/L. There exists an obvious synergism effect.