Toxic Effects of Paichongding on Brown Planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

Laboratory assays explored the potential of paichongding, a novel neonicotinoid insecticide, against the brown planthopper, Nilaparvata lugens(Stål) (Homoptera: Delphacidae). Cumulative mortality of N. lugensfollowing exposure was concentration and time dependent. Nilaparvata lugensnymphs were more sensitive to paichongding compared with the adults, and the first and second instars were the most susceptible. Median lethal concentration (LC50) values to instars I–II at 24, 48, and 72 h after treatment were 7.00, 0.46, and 0.13 mg/L, respectively. Brachypterous adults were more susceptible than macropterous adults, and the macropterous females were the least susceptible with LC50 values at 24, 48, and 72 h after treatment of 97.05, 58.70, and 1.26 mg/L, respectively. The median lethal time (LT50) significantly decreased with increasing concentration of paichongding. The LT50 for instars I–II decreased from 62.38 h at 0.2 mg/L to 25.13 h at 3.2 mg/L, whereas the LT50 values for macropterous females were 92.67 h at 0.2 mg/L and 52.65 h at 3.2 mg/L. These laboratory results suggested that paichongding has potential in controlling populations of N. lugens.Our preliminary study laid foundations for development and future use of paichongding in rice culture.