Abstract: Studies on resistance selection by abamectin and fenpropathrin and activity change of detoxicant enzymes of Panonychus citri（McGregor）were carried out in laboratory. P. citri was separately treated with abamectin and fenpropathrin imitating field chemicals selection pressure in order to breed its resistance. The results showed that the resistance has respectively reached 7.30-fold to abamectin and 17.11-fold to fenpropathrin after 12 times selection. The resistance mechanism was evaluated by activity measurement of enzymic inhibitors and detoxicant enzymes. It was concluded that the rise of resistance to abamectin was mainly associated with the increasing activities of acetylcholinesterase and mixedfunction oxidases. The resistance to fenpropathrin was attributed to carboxylesterase, acetylcholinesterase and glutathione transferase.

Key words: Panonychus citri, abamectin, fenpropathrin, resistanceselection, detoxicant enzymes