LAUSR

Simple Summary The brown planthopper (BPH), Nilaparvata lugens and white-backed planthopper (WBPH) Sogatella furcifera are major rice pests in many parts of Asia. This study was conducted to elucidate the action mechanisms in sublethal exposures of imidacloprid and sulfoxaflor on the feeding behavior of the planthopper. The sublethal concentrations of imidacloprid and sulfoxaflor inhibited the phloem feeding of the BPH and WBPH and decreased their reproduction longevity. Additionally, sulfoxaflor was effective in inhibiting feeding in the BPH, and imidacloprid was more effective in inhibiting feeding in the WBPH. Therefore, sublethal effects of insecticide vary according to insect pest species. Abstract The brown planthopper (BPH) Nilaparvata lugens and white-backed planthopper (WBPH) Sogatella furcifera are serious rice insect pests that cannot overwinter in Korea and migrate from southeast Asian countries and China. In this study, we investigated the sublethal effects of imidacloprid and sulfoxaflor on the biological parameters and feeding behavior of planthoppers. These sublethal concentrations significantly decreased the net reproduction rate (R0), the intrinsic rate of increase (rm), and the mean generation time (T). For BPHs, the total durations of nonpenetration (NP) waveform by imidacloprid (LC10 = 164.74 and LC30 = 176.48 min) and sulfoxaflor (LC10 = 235.57 and LC30 = 226.93 min) were significantly different from those in the control group (52.73 min). In addition, on WBPHs, the total durations of NP waveform by imidacloprid (LC10 = 203.69 and LC30 = 169.9 min) and sulfoxaflor (LC10 = 134.02 and LC30 = 252.14 min) were significantly different from those in the control group (45.18 min). Moreover, the LC10 and LC30 of these insecticides significantly decreased the phloem feeding time. In conclusion, imidacloprid had a better effect on the inhibition of feeding of the WBPH, and sulfoxaflor showed a better effect on the inhibition of feeding of the BPH. Therefore, it is suggested that treatment with sublethal concentrations of the above insecticides will reduce the feeding of BPHs and WBPHs on rice phloem.