Abstract: Experiments showed that lowest survival rate, longest duration of nymphsand lightest weight of brachypterous female occurred in the 2nd generation of brownplanthopper (BPH) Nilaparvata lugens (Stal) on feeding on resistant rice varieties. There were no obvious differences in the survival rate, duration of nymphs andweight of brachypterous female between feeding on resistant rice varieties IR26、Mudgo.ASD7 after 3rd generation and feeding on susceptible variety TN1. The 2nd generation of BPH was found to be key generation adapting to the resistant rice varieties. In the variation of virulence of the brown planthopper, the lowest activities of alanine transaminase (ALT) and aspartic transaminase (AST) and the highest activities of superoxide dismutase (SOD) and catalase (CAT) were detected in the 2nd generation of the BPH feeding on resistant rice varieties.

Key words: brown planthopper, resistant varietes, adaptability, metabolic enzymes, pro- tective enzymes