Susceptibility to neonicotinoids and risk of resistance development in the brown planthopper, <i>Nilaparvata lugens</i> (Stål) (Homoptera: Delphacidae)

<jats:title>Abstract</jats:title><jats:p><jats:bold>BACKGROUND:</jats:bold> In recent years, outbreaks of the brown planthopper, <jats:italic>Nilaparvata lugens</jats:italic> (Stål), have occurred more frequently in China. The objective of this study was to determine the susceptibility of <jats:italic>N. lugens</jats:italic> to neonicotinoids and other insecticides in major rice production areas in China.</jats:p><jats:p><jats:bold>RESULTS:</jats:bold> Results indicated that substantial variations in the susceptibility to different insecticides existed in <jats:italic>N. lugens</jats:italic>. Field populations had developed variable resistance levels to neonicotinoids, with a high resistance level to imidacloprid (RR: 135.3–301.3‐fold), a medium resistance level to imidaclothiz (RR: 35–41.2‐fold), a low resistance level to thiamethoxam (up to 9.9‐fold) and no resistance to dinotefuran, nitenpyram and thiacloprid (RR < 3‐fold). Further examinations indicated that a field population had developed medium resistance level to fipronil (up to 10.5‐fold), and some field populations had evolved a low resistance level to buprofezin. In addition, <jats:italic>N. lugens</jats:italic> had been able to develop 1424‐fold resistance to imidacloprid in the laboratory after the insect was selected with imidacloprid for 26 generations.</jats:p><jats:p><jats:bold>CONCLUSION:</jats:bold> Long‐term use of imidacloprid in a wide range of rice‐growing areas might be associated with high levels of resistance in <jats:italic>N. lugens</jats:italic>. Therefore, insecticide resistance management strategies must be developed to prevent further increase in resistance. Copyright © 2008 Society of Chemical Industry</jats:p>