Abstract: Feeding behaviors of imidacloprid resistant and susceptible populations of brown planthopper (BPH) on insect resistant (IR36) and susceptible rice (TN1) varieties were compared by electronic penetration graph technique (EPG). The results showed that seven typical waveforms (np, N1, N2, N3, N4-a, N4-b and N5 waveform) of imidacloprid-resistant and-susceptible BPH on different rice varieties were recorded during feeding. Compared with imidacloprid-susceptible population, imidacloprid-resistant population showed higher probe frequency, shorter probe time, longer phloem sap ingestion periods in sensitive rice variety TN1. However, there was no significant difference between imidacloprid-resistant and -susceptible BPH in the xylem sap ingestion periods. In resistant rice variety IR36, imidacloprid-resistant BPH showed lower probe frequency, shorter probe periods and longer xylem sap ingestion periods, but there was no difference of phloem sap ingestion waveform in two BPH populations. After feeding on IR36 for one generation, probe frequency and probe periods decreased, whereas phloem sap ingestion periods increased in the two BPH populations．

Key words: imidacloprid-resistant and -susceptible Nilaparvata lugens, resistant rice varieties, electronic penetration graph (EPG), feeding behavior